Sustainable Manufacturing and Design (Woodhead Publishing Reviews: Mechanical Engineering Series) [1 ed.] 0128221240, 9780128221242

Table of contents :
Front Matter
Copyright
Contributors
About the editors
Preface
Current tools and methodology for a sustainable product life cycle and design
Introduction
Tools for sustainable product design
Eco-design tools
P-SPD tools
SPD tools
Methodology considering multi-life cycle approach for closed loop material flow in SPD
Price-sensitive dynamic demand model
Quantities of returns and EOL component recovery strategies
Optimizing the objective functions
Future research and scope
Conclusion
References
Additive manufacturing for a dematerialized economy
Introduction
Welcome to 2040
Background
Continuous products
Additive manufacturing personalized products
Additive manufacturing adaptable products
Additive manufacturing for a dematerialized economy
Distributed manufacturing 2040
Key turning points 2030
Starting points 2020
Transition research
Conclusion
References
Sustainable friction stir welding of metals
Introduction
Materials and experimental work
Tensile test
Flexural test
Impact test
Theoretical considerations of energy supplied
Results and discussion
Conclusions
References
Heat pipe-embedded tooling for sustainable manufacturing
Introduction
Metal cutting practices
Dry machining
Minimum quantity lubrication (MQL)
Heat pipe-embedded cutting tools
Conclusion
References
Sustainable manufacturing of plastic packaging material: An innovative approach
Introduction
Flexible packaging
Rigid plastics packing
Literature review
Experimental works and lab tests
Results and discussions
Conclusion
References
Performance of microwave-irradiated WC-Co insert during dry machining of Inconel 718 superalloys
Research background
Microwave treatment
Material and methods
Results and discussion
Conclusions
References
Experimental study on friction stir welding of AA6061 aluminum alloy
Introduction
Literature review
Materials and methods
Results and discussions
Conclusions
References
Machinability study of Inconel 825 superalloy under nanofluid MQL: Application of sunflower oil as a base ...
Research background
Material and methods
Results and discussion
Equivalent chip thickness (tc)
Average segmentation spacing (DeltaS)
Segmentation frequency (fz)
Shear angle (θ)
Degree of chip segmentation or segmentation ratio (s)
Saw-tooth included angle (phi)
Conclusions
References
Performance enhancement approaches for Mahua biodiesel blend on diesel Engine
Introduction
Methodology
Biodiesel preparation
Combustion chamber modification
Experimentation by varying the combustion chamber design
Additives
Oxygenated additives
Metal-based additives
Experimentation for additives
Results and discussions for modification of combustion chamber geometry
Performance parameters
Brake thermal efficiency (BTE)
Brake-specific fuel consumption (BSFC)
Emission parameters
Hydrocarbons (HC)
Carbon monoxide (CO)
Carbon dioxide (CO2)
Oxides of nitrogen (NOx)
Results and discussions for additives
Performance parameters
Brake thermal efficiency (BTE)
Brake-specific fuel consumption (BSFC)
Hydrocarbon (HC) emission
Carbon monoxide (CO) emission
Carbon dioxide (CO2) emission
Oxides of nitrogen (NOx) emission
Conclusions
Future scope
Acknowledgments
References
Optimization of wear parameters of aluminium hybrid metal matrix composites by squeeze casting using Taguchi ...
Introduction
Experimental procedure
Wear test
Design of experiments
Results and discussion
Analysis of variance
Worn surface
Artificial neural networks
Conclusion
References
Index
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D
E
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Citation preview

SUSTAINABLE MANUFACTURING AND DESIGN

Woodhead Publishing Series in Mechanical Engineering

SUSTAINABLE MANUFACTURING AND DESIGN Edited by

KAUSHIK KUMAR Birla Institute of Technology, Ranchi, India

DIVYA ZINDANI National Institute of Technology, Silchar, India

J. PAULO DAVIM University of Aveiro, Aveiro, Portugal

An imprint of Elsevier

Woodhead Publishing is an imprint of Elsevier The Officers’ Mess Business Centre, Royston Road, Duxford, CB22 4QH, United Kingdom 50 Hampshire Street, 5th Floor, Cambridge, MA 02139, United States The Boulevard, Langford Lane, Kidlington, OX5 1GB, United Kingdom © 2021 Elsevier Ltd. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions. This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein). Notices Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the Library of Congress British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library ISBN: 978-0-12-822124-2 ISBN: 978-0-12-822161-7

For information on all Woodhead publications visit our website at https://www.elsevier.com/books-and-journals

Publisher: Matthew Deans Acquisitions Editor: Brian Guerin Editorial Project Manager: Fernanda A. Oliveira Production Project Manager: Nirmala Arumugam Cover Designer: Mark Rogers Typeset by SPi Global, India

Contributors Suman Chatterjee Department of Mechanical Engineering, National Institute of Technology Rourkela, Rourkela, Odisha, India

Saurav Datta Department of Mechanical Engineering, National Institute of Technology Rourkela, Rourkela, Odisha, India

J. Paulo Davim Department of Mechanical Engineering, University of Aveiro, Aveiro, Portugal

Thrinadh Jadam Department of Mechanical Engineering, National Institute of Technology Rourkela, Rourkela, Odisha, India

J. Jhansi MGIT, Hyderabad, India

U.S. Jyothi GRIET, Hyderabad, India

Hridayjit Kalita Department of Mechanical Engineering, Birla Institute of Technology Mesra, Ranchi, India

I. Kantharaj Department of Mechanical Engineering, Karunya Institute of Technology and Sciences, Coimbatore, Tamil Nadu, India

Ramakrishna Karanth Kimoha Entrepreneurs Ltd., Jebel Ali Free Zone, Dubai, United Arab Emirates

Yashaswini Karanth Department of Materials Science and Engineering, Texas A&M University, College Station, TX, United States

Kaushik Kumar Department of Mechanical Engineering, Birla Institute of Technology Mesra, Ranchi, India

M. Senthil Kumar School of Mechanical Engineering, VIT, Chennai, Tamil Nadu, India

Jennifer Loy Deakin University, Geelong, VIC, Australia

Siba Sankar Mahapatra Department of Mechanical Engineering, National Institute of Technology Rourkela, Rourkela, Odisha, India

Subash Chandra Mishra Department of Metallurgical and Materials Engineering, National Institute of Technology, Rourkela, Odisha, India

S. Mohanasundaram Department of Mechanical Engineering, Karunya Institute of Technology and Sciences, Coimbatore, Tamil Nadu, India

Vishal Naranje Department of Mechanical Engineering, Amity University, Dubai, United Arab Emirates

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L. Natrayan School of Mechanical Engineering, VIT, Chennai, Tamil Nadu, India

James I. Novak Deakin University, Geelong, VIC, Australia

Deepankar Panda Department of Metallurgical and Materials Engineering, National Institute of Technology, Rourkela, Odisha, India

Kshitij Pandey Department of Mechanical Engineering, National Institute of Technology Rourkela, Rourkela, Odisha, India

Rajakumar S. Rai Department of Mechanical Engineering, Karunya Institute of Technology and Sciences, Coimbatore, Tamil Nadu, India

Santosh Kumar Sahoo Department of Metallurgical and Materials Engineering, National Institute of Technology, Rourkela, Odisha, India

Anshuman Kumar Sahu Department of Mechanical Engineering, National Institute of Technology Rourkela, Rourkela, Odisha, India

M.V.N. Sankaram Department of Mechanical Engineering, BITS Pilani, Dubai, United Arab Emirates

S. Santhi MGIT, Hyderabad, India

J. Srinivas Mechanical Engineering, NIT Rourkela, Rourkela, India

U. Sudhakar SCSVMV University, Kanchipuram, India

X. Ajay Vasanth Department of Mechanical Engineering, Karunya Institute of Technology and Sciences, Coimbatore, Tamil Nadu, India

S.J. Vijay Department of Mechanical Engineering, Karunya Institute of Technology and Sciences, Coimbatore, Tamil Nadu, India

Mukesh Kumar Yadav Department of Mechanical Engineering, National Institute of Technology Rourkela, Rourkela, Odisha, India

About the editors Kaushik Kumar, B.Tech. (Mechanical Engineering, REC [Now NIT], Warangal), MBA (Marketing, IGNOU), and Ph.D. (Engineering, Jadavpur University), is presently an Associate Professor in the Department of Mechanical Engineering, Birla Institute of Technology, Mesra, Ranchi, India. He has 19 years of Teaching and Research and over 11 years of industrial experience in a manufacturing unit of Global repute. His areas of teaching and research interest are Composites, Optimization, Nonconventional machining, CAD/CAM, Rapid Prototyping, and Quality Management Systems. He has 9 Patents, 35 + Book, 30 Edited Book, 55 Book Chapters, 150 international Journal publications, 22 International, and 1 National Conference publications to his credit. He is on the editorial board and review panel of seven International and one National Journals of repute. He has been felicitated with many awards and honors. (Web of Science core collection 102 publications/h-index 10 +, SCOPUS/h-index 10+, Google Scholar/h-index 26+.) Divya Zindani, BE (Mechanical Engineering, Rajasthan Technical University, Kota), M.E. (Design of Mechanical Equipment, BIT Mesra), and presently pursuing PhD (National Institute of Technology, Silchar), has over 2 years of Industrial experience. His areas of interests are Optimization, Product and Process Design, CAD/CAM/CAE, Rapid prototyping, and Material Selection. He has 2 Patent, 8 Books, 8 Edited Books, 23 Book Chapters, 10 SCI journals, 7 Scopus Indexed international journals, and 7 International Conference publications to his credit. J. Paulo Davim is a Professor at the University of Aveiro, Portugal. He is also distinguished as honorary professor in several universities/colleges in China, India, and Spain. He received his Ph.D. degree in Mechanical Engineering in 1997, M.Sc. degree in Mechanical Engineering (materials and manufacturing processes) in 1991, Mechanical Engineering degree (5 years) in 1986, from the University of Porto (FEUP), the Aggregate title (Full Habilitation) from the University of Coimbra in 2005, and the D.Sc. (Higher Doctorate) from London Metropolitan University in 2013. He is Senior Chartered Engineer from the Portuguese Institution of Engineers with an MBA and Specialist titles in Engineering and Industrial Management as well as in Metrology. He is also Eur Ing by FEANI-Brussels and

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Fellow (FIET) of IET-London. He has more than 30 years of teaching and research experience in Manufacturing, Materials, Mechanical, and Industrial Engineering, with special emphasis in Machining & Tribology. He has also interest in Management, Engineering Education, and Higher Education for Sustainability. He has guided large numbers of postdoc, Ph.D. and master’s students as well as has coordinated and participated in several financed research projects. He has received several scientific awards and honors. He has worked as evaluator of projects for ERC-European Research Council and other international research agencies as well as examiner of Ph.D. thesis for many universities in different countries. He is the Editor in Chief of several international journals, Guest Editor of journals, books Editor, book Series Editor, and Scientific Advisory for many international journals and conferences. Presently, he is an Editorial Board member of 30 international journals and acts as reviewer for more than 100 prestigious Web of Science journals. In addition, he has also published as editor (and coeditor) more than 150 books and as author (and coauthor) more than 15 books, 100 book chapters, and 500 articles in journals and conferences (more than 280 articles in journals indexed in Web of Science core collection/h-index 57 +/10500+ citations, SCOPUS/h-index 62 +/13000+ citations, Google Scholar/h-index 80+/21500+ citations).

Preface The editors are pleased to present the book Sustainable Manufacturing and Design under the book series Woodhead Publishing Reviews: Mechanical Engineering Series. The book title was chosen as it depicts upcoming trends in the industrial world for the various critical applications. This book is a compilation of different aspects of the same. The concept of sustainability is something that is increasingly important to the way that we operate as individuals, as educators, and as societies more generally. Originally a term largely used in reference to the well-being of the Earth in the face of rapid development, and the threat of environmental degradation, the United Nations Brundland commission posited that “sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs.” This concept of sustainability has since taken root in different professions and academic disciplines and is now at the heart of how we look at the problems facing the world— from the macro to the micro, to the usage of energy and the emerging new impacts on our environment. Sustainability means different things to different people, from engineers to charity workers, architects to product designers, politicians to philosophers, and medical doctors to engineers. Mass production, consumption, and waste in industrialized/urbanized societies have a profound effect on the planet’s living systems and vital resources. There has been a dramatic increase in the concentration of CO2 in the environment. The kneeling curve delineates that the concentration of CO2 has reached 400 ppm in 2013 in comparison to 315 ppm in 1958. The consequences are the strong greenhouse effects. Therefore, the two main focuses of the 21st century have been on the environment and the optimum utilization of the resources. Design and innovation have the potential to regenerate the natural environment and community culture, while enhancing the value of products/services to business, customers, and society in general. To meet emerging scientific/technological challenges associated with sustainability, new design thinking, methods, and tools are required. This has called for designing of sustainable products and use of sustainable manufacturing technologies that have become strategically important for the different production and manufacturing industries around the world. Sustainable products are a solution to meet the environmental needs as well as ensure the quality to the customer and are also the

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means to achieve the harmony of natural environment, social culture, and economic development. In the design for environment process, designers may look at the source, makeup, and toxicity of raw materials; the energy and resources required for manufacturing the product; and how the product can be recycled or reused at the end of its life. Balanced with other product considerations such as quality, price, producability, and functionality, ecodesigned products are environmentally and economically viable alternatives to traditional products. Smart sustainable design creates products that use less energy and natural resources; products that can be recycled easily or reused; and products that promote energy and materials’ efficiency in consumers’ lives. The production of sustainable products should also entail sustainable technologies and thus the traditional manufacturing methods should be converted to sustainable conserving machines that benefit the environment as a whole. The edited book would provide to establish an effective channel of communication between the academic community of design and manufacturing engineers in academic and research institutions, professionals working in industry and related businesses, and government agencies and policy-makers concerned with sustainability issues in design and manufacturing, which also forms the mission of this book series. So the edited book is to provide academics/researchers and industry practitioners a platform to discuss new solutions for product design and development as well as the manufacturing technologies with due consideration to the complex issues surrounding sustainability. Further, the edited book aims to simulate innovation and development of sustainable products and production technologies. The edited book comprises of the articles by leading thinkers and practitioners from around the world. The chapters in the book have been categorized in Four Sections, namely, Section I: Sustainability Methodology; Section II: Sustainability in Manufacturing; Section III: Sustainability in Product Design; and Section IV: Optimization. Section I contains Chapters 1 and 2, whereas Section II has Chapters 3–5, Section III with Chapters 6–8, and Section IV contains Chapters 9 and 10. Section I starts with Chapter 1 which provides an overview of current tools and methodology for a sustainable product lifecycle and design. Sustainable product designing has become the major concern for industries due to increased awareness in the society toward climate change and green economy. Many tools encompassing methodologies and frameworks have been proposed on achieving sustainability in the entire product lifecycle (from the cradle to the grave) considering the three important aspects, i.e., economics,

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social, and environmental. Based on the utilization of these aspects, sustainable product design tools can be broadly classified into eco-design tools, PSPD tools and SPD tools, the description of which have been detailed in this chapter. A methodology for a closed loop material flow involving a multi lifecycle approach and evaluating the EOL strategies and prices of the product in the market has been explained in detail. The methodology employs a bass diffusion dynamic demand model incorporating variations in the product pricing and maximizing the product lifecycle profit, minimizing energy and water usage over the entire lifecycle, with a variety of product. Chapter 2 elaborates on additive manufacturing for a dematerialized economy and focus of this chapter is on the potential of additive manufacturing (3D printing) to be a key sustainability tool in working toward a lowimpact, dematerialized society. To reduce the environmental impacts of manufacturing requires more than a change in production practices; it needs a rethink of society’s economic values and structures to change the public’s relationship with products and consumption. This is a difficult future to create, or even envisage, in societies hampered by the entrenched industrial practices and consumer expectations built during the last century. However, recent developments in digital technology are providing opportunities to disrupt and reframe production practices and commercial interactions, which could enable a shift to product services systems over products, distributed manufacturing over centralized production. In the chapter, backcasting is used to propose an alternative future, and then work backwards, to map out ways forward from now, rather than a prediction modeling approach based on existing trends and trajectories. Chapter 3, the first chapter of Section II, enlightens the readers with application of friction stir welding toward sustainability. Friction stir welding is solid-state joining technique widely used in automobile, aerospace, and ship building sectors for welding similar and dissimilar metals and alloys without expending huge amount of energy. The welded joints have relatively good strength and corrosion/wear characteristics as well as fine microstructure leading to limited defects. Friction stir welding has basically begun for joining soft metals and alloys. Aluminum and its alloys have wide use in industrial sectors due to their light weight and good strength. Friction stir welding is also intended for joining of aluminum with low melting point metals like copper, zinc, and magnesium sheets. Unlike fusion welding schemes, here the frictional heat between the tool and weld materials does not create the temperatures to melting points; rather, it plasticizes the region temporarily and solidifies the mixture at the joint interface. This chapter deals with the

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sustainable friction stir welding of aluminum alloys of variable compositions. The influence of cutting parameters and tool geometry on the mechanical characteristics of joint is discussed. Tensile strength and impact resistance of welded portions are obtained. Theoretical energy required in each case along with other data is estimated for all experimental cases. Chapter 4 describes heat pipe-embedded tooling for sustainable manufacturing. Even in this era of Nano technology and additive manufacturing, machining plays a vital role in production and contributes to nearly 70% in product development. Generally, a rise in temperature and cutting force is observed while machining. These adverse effects contribute to the poor product quality and tool life such as rough surface finish, increased tool wear, higher rate of part rejections, etc. It has been a practice for decades to apply coolant and remove the excess heat near the tool-work interface, thereby maintaining the desired dimensional accuracy and surface finish. But this practice has originated other problems such as increase in overall production cost, increase in industrial waste, increase in land and water pollution, increase in health hazard of operators, etc. This chapter deals with using heat pipes as one of the many sustainable techniques that has been practiced in various industries to remove heat effectively. Heat pipes embedded in cutting tools serve as an alternate to remove the excessive heat present at the interface between the tool and workpiece. The chapter demonstrates the behavior of the heat pipe-embedded tools during machining, showing a sizeable reduction in the temperature at tool-work interface. Interesting results such as reduction in cutting force while employing such tools have been clearly observed. The chapter also demonstrates the possibility of carrying out dry machining operation through sustainable technique. Chapter 5 provides an innovative approach toward sustainable manufacturing of plastic packaging material. In recent times, there had been intense pressure on packaging manufacturers and FMCG companies because of excessive use of plastics, short first use cycle of plastic packaging, high carbon footprint that the packaging leaves behind, and enormous quantity of plastic waste that ends up in water streams and as landfills. Further, sustainability is also a major concern as plastic is a nonrenewable resource. Hence, there is an immediate need to reduce the quantity of plastics used for packaging by downsizing and to enable primary recycling of all the packaging material used. Recycling is possible when we eliminate the use of dissimilar material that will prevent such recycling because of the immense challenges to segregate such dissimilar material in the packaging postconsumer use and because of the high mechanical and barrier property needs of the packaging

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material to withstand the rigors of the transportation and extended shelf life, it is necessary that packaging material remains sturdy even after downsizing. In the present chapter, trials were carried out with Silicon Oxide and Aluminum Oxide nanoparticles with Polypropylene and Acrylonitrile Butadiene Styrene through manual blending and conventional injection molding process. Poly Propylene Graft Maleic Anhydride is used as a compatibilizer. Samples thus produced are subjected to top load tests. Improvement in top load test performance and fatigue performance is observed in samples produced with nanoparticles in comparison with samples with only Poly Propylene resins. Chapter 6, which starts the section on sustainability in product design, talks about performance of microwave irradiated WC-Co insert during dry machining of Inconel 718 superalloys. Uncoated WC-Co tool insert is volumetrically heated through microwave irradiation to explore potential benefits of mechanical properties including higher hardness, lower residual stress, and better wear resistance, which in turn improve machinability of “difficult-to-cut” Inconel 718 superalloy. Household domestic microwave oven is used for microwave irradiation, in which activated charcoal powder is used as microwave susceptor. Dry turning experiments are conducted on Inconel 718 workpiece using microwave-treated tool at varied cutting speed; corresponding tool-tip temperature and flank wear depth are measured. It is experienced that as compared to conventional (untreated) insert, better machining performance is attributed to microwave-treated insert. The chapter also provides detailed analysis on tool wear morphology. Chapter 7, the next chapter, concentrates on friction stir welding of a lightweight material, i.e., AA6061 aluminum alloy. Friction stir welding is a prominent solid-state welding process widely used in different industries to join similar and dissimilar lightweight and low strength metals and alloys which is feasible by fusion welding process. In present chapter, AA6061 Aluminum alloy plates of 6 mm thickness are friction stir welded with three distinct types of tool pin geometry, namely, circular, equilateral triangular, and square pin. Rotational speed of tool, transverse speed, and tool pin geometry are taken as process parameters to investigate the effect on mechanical and microstructural properties of the joint. Taguchi’s L9 orthogonal array was used to design the experimental layout for different experiments. Tensile test and micro-hardness test have been carried out to examine the strength of Friction stir welded sample. Fractographic analysis of Fracture surface by Scanning Electron Microscope (SEM) shows the ductile mode of fracture. Microstructural analysis by optical microscope shows various types of defects

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in friction stir welded joint due to change in input process parameters. To find out best level of parameters setting for maximum strength of joint, Taguchi design of experiment was used. ANOVA analysis was also carried out to find the significant parameter affecting the strength of FSW joint. Chapter 8, the last chapter of the Section III, provides insight about application of Sunflower Oil as Base Cutting Fluid with MWCNTs and nanoAl2O3 as Additives during machining of Inconel 825 Superalloy. In recent times, application of nanocutting fluid has gained much importance over traditional dry machining as well as wet cooling (flood and MQL). Inclusion of nano-sized particles/tubes within base cutting fluid enhances cooling, lubrication, and heat transfer coefficient of the resultant fluid. In the present chapter, machining performance of “difficult-to-cut” aerospace superalloy Inconel 825 under nanofluid MQL (NFMQL) environment has been investigated. Two types of nanofluids are prepared by dispersing Multi-Walled Carbon Nanotubes (MWCNTs), and nano-Al2O3 powder, separately within sunflower oil (base fluid). Machining performance is evaluated in purview of cutting force, approximate tool-tip temperature, and progression depth of flank wear. Various modes and mechanisms of tool wear along with chip morphology are studied in detail. It is experienced that CNT-based NFMQL outperforms alumina-based NFMQL. Chapter 9, the commencing chapter of the last section of the book, i.e., Section IV, concentrates on performance enhancement approaches for Mahua biodiesel blend on diesel engine. This is an effort toward development of alternative fuels due to depletion of petroleum-based fuels availability from time to time. The present chapter is focused on Mahua Biodiesel, which is derived from nonedible source of Mahua oil; because of high viscosity, poor atomization of fuel, deposition of carbon, etc., it is not feasible to utilize straight vegetable oils. In order to overcome these limitations, biodiesels are produced using transesterification. To have compatibility with existing diesel Engines, these transesterified oils are used at optimal blend. This chapter is aimed to present a case study on modifying the design parameter of varying combustion chamber geometry and fuel additives such as oxygenated additive and metal-based additive, improving the performance of the Engine. Further, the results on two combustion chamber geometries, viz., hemispherical and toroidalgeometries are discussed. The variations of Performance, Combustion and Emission trends with oxygenated additive of ethanol and metal-based additive of alumina are presented. The concluding chapter of the section and the book, Chapter 10, concentrates on optimization, i.e., optimization of wear parameters of Aluminum

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hybrid metal matrix composites by squeeze casting using Taguchi and Artificial Neural Network. The chapter is aimed to investigate the wear rate of AA024 reinforced Al2O3/SiC/Gr fabricates using the squeeze casting technique. Taguchi method was used to optimize the processing parameters, namely, applied load, sliding distance, and sliding velocity. Experimental design was carried out by L27 orthogonal array. ANOVA was executed to recognize the influence of specific factors. Wear mechanism, surface morphologies, and composition of the composites have been studied using SEM with EDS. Optimized results were also predicted with the artificial neural network (ANN). The ANN and regression model predicted the wear rate with 95% accuracy. First and foremost, we would like to thank God. It was His blessings that this work could be completed to our satisfaction. You have given the power to believe in passion, hard work, and pursue dreams. We could never have done this herculean task without the faith they have in You, the Almighty. We are thankful for this. We thank our families for having the patience with us for taking yet another challenge which decreases the amount of time we could spend with them. They were our inspiration and motivation. We would like to thank our parents and grandparents for allowing us to follow our ambitions. We would like to thank all the contributing authors as they are the pillars of this structure. We would also like to thank them to have belief in us. We would like to thank all of our colleagues and friends in different parts of the world for sharing ideas in shaping our thoughts. Our efforts will come to a level of satisfaction if the professionals concerned with all the fields related to coatings get benefitted. We owe a huge thanks to all of our Technical reviewers, Editorial Advisory Board Members, Book Development Editors, and the team of ELSEVIER for their availability for work on this huge project. All of their efforts helped to complete this book and we couldn’t have done it without them. Last, but definitely not the least, we would like to thank all individuals who had taken time out and helped us during the process of editing this book; without their support and encouragement, we would have probably given up the project. Kaushik Kumar Divya Zindani J. Paulo Davim

CHAPTER ONE

Current tools and methodology for a sustainable product life cycle and design Hridayjit Kalitaa, Kaushik Kumara, and J. Paulo Davimb a

Department of Mechanical Engineering, Birla Institute of Technology Mesra, Ranchi, India Department of Mechanical Engineering, University of Aveiro, Aveiro, Portugal

b

1.1 Introduction Sustainability has become an important aspect to be considered while planning and designing for the different products in the manufacturing industry and has been a major area of research interest [1]. Sustainability can be realized as an efficient and effective system in terms of the social, economic, and environmental impact of the manufacturing products on their stakeholders and throughout their entire life cycle [2]. The entire product life cycle denotes the time period from the material extraction, premanufacturing, manufacturing, usage to the post-usage of the product. Since 80% of the sustainability impacts of a product are required to be sorted out in the designing phase [3–5], a systematic and robust framework is needed which takes into account the cost and time factors in the product life cycle sustainability. End of life (EOL) and end of use (EOU) strategies after collection from the customers ensure a closed loop material flow (circular system) in reusing, remanufacturing, and recycling of products and requires strong managerial relationships and coordination among all supply chain partners [6]. For improvement in sustainability of product life cycle by facilitating closed loop material flow, a 6R approach considering reuse, redesign, recycle, reduce, recover, and remanufacturing has been proposed by Jawahir et al. [7]. A triple bottom line concept [8,9] in the product designing phase based on the 3 major sustainability aspects, i.e., economic, social, and environment for obtaining maximum social benefit, minimum environmental impact, and maximum economic benefit to its stakeholders, can be implemented. Balancing the three dimensions of sustainability, and at the same time conforming to the required functionality, is the purpose of a sustainable Sustainable Manufacturing and Design https://doi.org/10.1016/B978-0-12-822124-2.00001-9

© 2021 Elsevier Ltd. All rights reserved.

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product design and manufacturing [10,11]. In the first wave of sustainability, only ecological designs considering only environmental aspects of the sustainability were practiced, while social and economic aspects were not considered. Related studies in eco-design tools are included in references [12–15]. However, nowadays, a more comprehensive sustainable product design considering all three aspects has been trending as in the work of [16]. With the introduction and amendments in the circular economy package of the European commission (EC) to adopt new action plans and targets for implementation of eco-designs, the manufacturers were given the responsibility for successful execution of the product life cycle in their End of life (EOL) stages [17]. With the view to integrate sustainable development (SD) into the businesses, the manufacturers need to consider the Extended Producer responsibilities (EPR) entitling the producers to take control of the impact of the products on environment throughout the whole product life cycle period [18]. Individual producer responsibility (IPR) and collective producer responsibility (CPR) are two different ways of implementing and executing EPR (collectively or individually). IPR basically entitles a single producer to bear the cost of treatment of EOL products, whereas in CPR, collective responsibilities of the multiple producers towards expenses in EOL treatments are considered [19]. A major issue in integrating EOL strategies in the design phase is their uncertainties on what will be left out of the product quality after usage period. The consumption behavior of the customers in various market segments greatly affects the quality of the product received for EOL. As already mentioned, the eco-designs were the only practiced tools for injecting sustainability in the product design in its first wave. Chang et al. [15] reviewed life cycle assessment (LCA) for sustainability in product design considering only the environmental aspects. In the reviewed article for sustainable product designing by Buchert et al. [20], 11 methods were given, 3 methods of which were separated that considered all 3 sustainability aspects. The common methodology for considering the economic aspect of sustainability by life cycle costing was first introduced in 2007 Gundes [21], followed by a number of other researches [22,23]. On the other hand, the social dimensions and their methodological guidelines were first evaluated and prepared in 2009 by the United Nations Environment programme. In the current paper, the tools currently available for sustainable product design as suggested in [24] have been classified into eco-designs, partial sustainable product design (P-SPD), and sustainable product design (SPD) in Section 1.2. A methodology for a closed loop material flow system based

Current tools and methodology for a sustainable product life cycle and design

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on SPD has been described considering variations in pricing of the products and implementation of different EOL strategies by employing Base diffusion demand model.

1.2 Tools for sustainable product design The traditional product design approaches are generally based on meeting the requirements of the customers, i.e., the quality, cost, and functionality of the products, and are divided into 4 stages [25]. In the first stage, thorough planning is performed and definition of the problems explored. In the second stage, conceptual design is initiated by identifying the product functions, generating alternative concepts, and determination of design specification. In the 3rd stage, selection of the best concept is performed by evaluating the alternative concepts. Lastly, further evaluations, elaboration, and optimization of the final concept are done along with manufacturing, maintenance needs, documentation, and communication. Sustainable product development (SPD) tools, on the other hand, are generally based on looking into the entire product life cycle (from cradle to grave): functionality and performances in ecology, social, and economic aspects [26]. The tools in eco-design, P-SPD, and SPD are described in detail, the effectiveness of which is largely dependent on the activity in product design stages and life cycle.

1.2.1 Eco-design tools The term “Eco-design” tools and “Design for environment (DfE)” tools can be used interchangeably for use in USA and Europe, respectively [27]. Design for environment is generally employed for a single phase in product life cycle by integrating environmental factors into it, whereas Eco-design tools are used for an entire product life cycle, thus broadening the scope [27,28]. Eco-design tools can perform an intensive analysis of the product to a quantifiable solution for an improved sustainability performance. Devanathan et al. [29] looked into 30 eco-design tools and classified them into 3 categories which are the life cycle assessment (LCA)-based tools, quality function deployment (QFD) tools, and Checklist-based tools. LCA is the most commonly used tool which gives quantifying results of the environmental impact on each stage in the product life cycle (from cradle to grave), though it suffers from the drawback that a large amount of final product data are required to evaluate the end strategies to be adopted for the EOL

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products [11]. QFD employs the “house of quality (HoQ)” to incorporate the environmental objectives to the product design [11].

1.2.2 P-SPD tools As already mentioned, eco-design tools concerning the environmental impact on the product life cycle were used previously which neglected the social and economic aspects. Later, it was transformed to a more comprehensive tool, enhancing its scope, application, and boundary and making way for a complete sustainable product design concept. These improved tools are now able to take into consideration even the social and economic aspects of the product life cycle. When one of the newly included aspects (either economic or social) is merged with the environmental impact model of a sustainable product design, it is called P-SPD since no consideration is made to involve all the 3 sustainability aspects. In the traditional methods of product designing, quality was incorporated with the view to enhance the company profit; therefore, it was not seen as a social factor, but rather an economic issue. Still in many partial sustainable product designs along with quantity of stock, the parameters concerning quality were included in the economic domain [30], which further neglected the social values of the quality aspects of sustainability. In the modelling practice of P-SPD, Gmelin and Seuring [31] observed that factors concerning social aspects have been largely avoided. P-SPD tools were commonly seen employing methods in QFD due to their convenience in applying in the early stage of the product development and without the requirement of detailed information of the product [10].

1.2.3 SPD tools As already discussed, the term “Sustainability” in the true sense refers to the product design framework which considers the three dimensions of the sustainability, i.e., environmental, economic, and social aspects of the product life cycle. These are robust systems that can be improved with time to accommodate more information from each stage of the product life cycle. As clear from the literature [24], P-SPD tools did not consider in the true sense the economic benefit in their sustainable product design models and relied on performing cost analysis. To eliminate this issue, SPD employed the life cycle costing (LCC) that has been adopted from the cost accounting [32] with other methods such as value analysis and cost benefit analysis that is included in the economic sustainability assessment [33]. On the other hand,

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for evaluation of social impacts on product life cycle, Social life cycle assessment (S-LCA) was introduced, the guideline of which was introduced by United Nations project team [34,35]. SPD tools can be considered as multidisciplinary tools and are complex in nature for new users. It is due to the integration of tools from different fields coming together while taking into consideration all the three aspects of sustainability as can also be observed from the literature [24]. Moreover, most of the tools in this category are still in their infancy period of development. Contrary to the P-SPD tools that are based on Quality function deployment (QFD), full SPD tools are based on a diverse concept that facilitates triple bottom line of sustainability.

1.3 Methodology considering multi-life cycle approach for closed loop material flow in SPD The concept of 6R (reuse, redesign, recycle, reduce, recover, and remanufacturing) was first introduced by Jawahir et al. [7] for improvement in the sustainability of the product design and ensuring a closed loop material flow system by effectively implementing various EOL strategies. 6R closed loop material flow approach ensures a total sustainable product design during the entire life cycle with several approaches to tackle the integration [36]. Aydin et al. [37] adopted a closed loop material flow system to investigate the issues in product life cycle and EOL management for better decision making. Gan et al. [38] adopted a linear and stochastic demand function to study the effect of the product pricing for sustainable product design. Chen and Chang [39] proposed a demand model considering multiple periods, which is sensitive to prices in order to estimate the dynamic prices of new and remanufactured products. For measuring quality of the remanufactured products and enhancement in the maximum profit, a consumer demand model considering the quality, price, and environmental preferences was proposed by Cui et al. [40]. In order to evaluate for the design alternatives and find appropriate EOL strategies, a multi-objective optimization method based on a probabilistic model has been adopted by Ameli et al. [41] for simulating product family under IPR [42]. A closed loop material flow methodology has been proposed by Badurdeen et al. [43] to obtain the optimal configuration of the product employing a multi-life cycle approach, considering life cycle cost and several environmental criteria. Estimation of the product demand was done through

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expert opinions. This closed loop material flow methodology has been extended in [44] which adopts a Bass diffusion demand model for evaluation of the prices of the products and where both discrete and continuous variables are employed, thus increasing complexity. Thus, for reduction in environmental impacts of a variety of products and enhancing economic profit, the methodology encompassing a number of sequential steps has been described in detail below

1.3.1 Price-sensitive dynamic demand model Demand models are being developed to incorporate the effect of selling prices in different demand cases such as quadratic, multiplicative, additive, and exponential [45,46], though these models do not take into account the multi-life cycle concepts of product development. Bass diffusion model has been proposed with the motive to enhance the marketing strategies and production decisions in a product development process considering market potential, imitation effects, and innovation effects. An S-shaped growth pattern is seen in the sales of technologies and consumer durables based on the diffusion model of time dependency. The projected demand estimate D(t) for a given time (t) can be given as follows:
 N ðt  1Þ DðtÞ ¼ ½m  N ðt  1Þ p + q m Here, N(t  1) is the cumulative demand for a time period of “t  1,” “m” represents market potential, and p and q are innovation and imitation coefficients, respectively. Robinson and Lakhani [47] later modified the Bass model by incorporating the effect of pricing of the product. The demand estimate, D(t), tends to vary exponentially with the pricing of the product and can be expressed as given below:
 N ðt  1Þ kPr ðtÞ DðtÞ ¼ ½m  N ðt  1Þ p + q e m where Pr(t) represents product price at a time period “t.” This model faces a significant problem when the value of “k” approaches “0,” which basically represents a constant number. The pricing term was, therefore, later substituted with a plastic elasticity term of the demand by Jain and Rao [48] giving the demand estimate. The expression is as follows:

Current tools and methodology for a sustainable product life cycle and design

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 N ðt  1Þ Dðt Þ ¼ ½m  N ðt  1Þ p + q ðPr ðtÞη Þ m Thus, the number η representing price elasticity determines the rate of decrease in the demand of the product. The Bass diffusion model parameters can be determined considering the historical sales data of the product by employing maximum likelihood method [49] and nonlinear regression [50]. The parameters can also be fixed or assumed by considering expert views and opinions and looking into diffusion model patterns of a similar product produced previously [51].

1.3.2 Quantities of returns and EOL component recovery strategies Quantities of EOL component returns are determined from the estimation of the demand “D(t)” at time “t” and considering a return rate βn(t) for the same time period. The equation can be given as below: Rn ðt + uÞ ¼ Dn ðt Þβn ðtÞ,“t” ¼ 1; 2;3;4,…:T U X Rn ðt Þ ¼ 0 t¼1

The suffix “n” in the above equations represents the type “n” product, “u” represents the time period of usage, and Rn(t + u) represents the number of EOL returns at time (t + u) of the “n” type product. “T” denotes the total demand cycle time period. Quantity of returns equals to zero during the usage period of the product, and in other cases, these are assumed to be derived from expert recommendation based on historical data or data of a similar type product. The returned components are then recycled, remanufactured, sold, reused, and disposed, the quantities of which can be determined considering the percentages of quantities of product for EOL recovery (δ) and the number of product returns. These can be expressed as: N X

nrcy nkl ðt + 1Þ ¼

N X

n¼1

n¼1

N X

N X

n¼1

nrm nkl ðt + 1Þ ¼

n¼1

δrcy kl ðt ÞRn ðt Þ δrm kl ðt ÞRn ðt Þ

Hridayjit Kalita et al.

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N X

nsol nkl ðt + 1Þ ¼

n¼1 N X

δsol kl ðt ÞRn ðt Þ

n¼1

nreu nkl ðt + 1Þ ¼

n¼1 N X

N X

N X

δreu kl ðt ÞRn ðt Þ

n¼1

ndis nkl ðt + 1Þ ¼

n¼1

N X

δdis kl ðt ÞRn ðt Þ

n¼1

Since, all the delta terms represent the recovery strategies after use for the “k” component of “l” variant. Therefore, rm sol reu dis δrcy kl ðt Þ + δkl ðt Þ + δkl ðt Þ + δkl ðt Þ + δkl ðt Þ ¼ 1,k ¼ 1; 2; 3,…:K and l ¼ 1;2; 3,::Lk

The subscript “n,” “k,” and “l” represent the product, component, and variant, respectively. The percentages generally remain the same for the same time period, but can vary with different demand cycle stages. The recovery percentages can be obtained from experts and senior managers considering the available previous data. For the (re) manufacture of hybrid products, component variants can be in the form of new, reused, remanufactured, and recycled ones. The quantity of the component variants can be expressed in terms of the number of components in different forms mentioned above for the “n” type product, “k” type component, and variant “l,” which is given as: rcy reu rm Dn ðtÞxnkl ¼ nnew nkl ðt Þ + nnkl ðt Þ + nnkl ðt Þ + nnkl ðt Þ

where, k ¼ 1,2,3, …K and l ¼ 1,2,3, …Lk. When the value of xnkl is 1, it generally represents the variant “l” of the component “k” for the product type “n” and the value is 0 when it is not the case as described. Thus, it is a binary condition to satisfy the equation which can be expressed as: Lk X

xnkl ¼ 1

l¼1

where, k ¼ 1,2,3, …K and n ¼ 1,2,3,..N. The equation describes that only one variant can be possible of a given component for the manufacture of a hybrid product.

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1.3.3 Optimizing the objective functions A multi-life cycle multiple product optimization model formulation can now be implemented considering three major objective functions with the motive to evaluate the product pricing and its configuration. NSGA II or non-dominated sorting genetic algorithm is the most commonly used optimization algorithm for solving such problems in multi-objective functions, which surpasses in its computational speed, convergence, and diversity in solutions from other optimization algorithm such as strength pareto evolutionary algorithm (SPEA) and Pareto archived evolution strategy (PAES). Due to the adoption of strategies such as effective constraint handling and preservation of elitism, the quality of the solution obtained in NSGA II is much superior. Also, by handling crowded comparison rather than handling by user-defined parameters, NSGA II can ensure enhancement in diversity mechanism. Optimization of the decision variables involved in the determination of prices of the products and product configuration (such as binary variables xnkl) can be given as follows: high Pr low n  Pr n ðt Þ  Pr n

where Prn(t) represents the price of the nth product at time “t,” Prlow n and high Prn represent the lowest and the highest prices, respectively, in the range of prices of the nth product. The optimization aims to find the best solution for achieving economic benefit and reduction in environmental impacts during the entire life cycle by considering three major objective functions which are maximizing profit for the entire product life cycle, minimizing energy usage during the whole product life cycle, and minimizing water usage during the whole product life cycle. The formulation of these objective functions can be described in detail below: 1. Maximizing profit during the entire product life cycle: The total life cycle profit (TLP) can be determined by subtracting the total life cycle cost of the product from the total revenue from the product. The total revenue of the product in time “t” can be expressed as the multiplication between the demand estimated for the same time period (Dn) and the prices of the product at time “t” (Prn). The expression for TLP can be given as below: TLP ¼

N X T X n¼1 t¼1

½Dn ðt ÞPr n ðt Þ  TC n ðt Þ

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The total life cycle cost of the nth product during the time period “t” (TCn) can be given in terms of all the costs such as fixed cost, costs involved in executing EOL strategies (new, reused, remanufacturing, and recycling), usage cost, and overtime cost. The expression can be given as below: TC n ðtÞ ¼ cnfix + cklrm

Lk K X X 

 new reu reu rm xnkl nnew nkl ðt Þckl + nnkl ðt Þckl + nnkl ðt Þ

k¼1 l¼1 rcy sol use + nnkl ðtÞcklrcy  nsol nkl ðt Þrkl Þ + Dn ðt Þcn + OT ðt Þ

" OT ðtÞ ¼

N X

# Dn ðtÞ  CP c ovt when

n¼1

N X

Dn ðtÞ > CP

n¼1

Or else OT ðtÞ ¼ 0 new reu reu rm rcy Here, cfix n is the fixed cost of the nth product, ckl , ckl , ckl , ckl , and ckl basically represent the costs involved in components that are new, reused, remanufactured, and recycled, respectively, of the lth variant of the component “k.” rsol kl is the unit revenue earned by selling the lth variant of the component “k” and cuse n is the usage cost of the nth product. OT(t) is the overtime cost of production for ensuring productivity at time “t” and to satisfy the demand (Dn(t)) where CP is the production capacity and covt is the overtime cost of the nth product. 2. Minimizing average energy usage for the entire product life cycle: The optimization in this case involves an average energy usage criterion that divides the estimated total energy usage (TEUn(t)) during the time “t” by the total product demand (Dn(t)) that varies with product pricing. The average energy usage per product is then extended to all the type of products and is divided by the total number of types of products, N. The expression is given below:

2

T X

3

TEU n ðtÞ7 N 6 X 6 t¼1 7 6 7=N EU ¼ 6 X 7 T 5 n¼1 4 Dn ðtÞ t¼1

TEU n ðtÞ ¼

Lk K X X k¼1 l¼1

 rcy rcy  new reu reu rm rm xnkl nnew nkl ðt Þekl + nnkl ðt Þekl + nnkl ðt Þekl + nnkl ðt Þekl

+ Dn ðtÞeuse n

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reu rm rcy enew kl , ekl , ekl , and ekl represent the energy consumed by the component “k” of variant “l” which are new, reused, remanufactured, and recycled, respectively. euse n represents the unit energy consumed by the nth product during its usage period. 3. Minimizing average water usage for the entire product life cycle: The third optimization is performed with a view to minimize the average water usage in terms of the water consumed per product considering all the four life cycle periods. It is formulated by dividing the total water usage (TWUn(t)) of the nth product at a time period “t” with the estimated demand (Dn(t)) of the nth product at the same time period. The expression obtained is extended for all the products and then the whole is divided by the total number of products (N).

2

T X

3

TWU n ðtÞ7 N 6 X 6 t¼1 7 6 7=N WU ¼ 6 X 7 T 5 n¼1 4 Dn ðtÞ t¼1

TWU n ðtÞ ¼

Lk K X X

 rcy rcy  new reu reu rm rm xnkl nnew nkl ðt Þwkl + nnkl ðt Þwkl + nnkl ðt Þwkl + nnkl ðt Þwkl

k¼1 l¼1

+ Dn ðtÞwnuse reu rm rcy wnew kl , wkl , wkl , and wkl represent water consumed by the component “k” of variant “l” which are new, reused, remanufactured, and recycled, respectively. wuse n represents the water consumed during the usage period of the product type “n.”

1.4 Future research and scope The above detailed sustainable product life cycle and design tools though have been developed to consider the social, economic, and financial aspects of the product life cycle, researches on their practical utility and complications in their implementation in industries and commerce have become a hot point for making improvements. The tools need to be more userfriendly, adaptable, simple, ease of analysis, and a better guidance mechanism for an optimum resource and time utilization. In industries, the maturity level of these tools plays a vital role in determining the practicability of

Hridayjit Kalita et al.

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different SPD tools, which is basically based on the consistency and element standardization such as weights, units of measurement and procedures, system boundaries, methods in quantification, and data acquisition modes. Most of the SPD tools lack in their consistencies in measurement methods and indicators and are in their infancy period. The usability in industries of the SPD tools can also be enhanced by integrating the methodologies to the computer-aided design (CAD) tools and softwares. Dealing with uncertainties and stochastic variables is another major challenge in the modelling practice of SPD tools to maintain a closed loop system, ensuring cost-effective and environmental-friendly measures for both forward and return strategies. All recent developed SPD tools fail to consider the emotional aspect or the user experience design (customer satisfaction) in their product design strategies, which is yet to be explored and improved in future research. Most of the recently developed SPD tools are complex and are difficult to understand which gives an impression of expert specific tools. This has to be tackled with collaboration between the government agencies, industrial practitioners, and academic researchers for development of tools that enhance ease of usage and adoption in industries and commercial places. The product line design that has been described in detail in the paper can be implemented seamlessly by design engineers and supply chain managers to address the total life cycle of the products including the activities in recovery strategies of EOL products, during premanufacturing and manufacturing, and during usage period, for better economic and environmental performances of their firms. Also, the bass diffusion model employed here can take into account the dynamic issues in the market and estimate demand for different products.

1.5 Conclusion The need for adoption of sustainable approach in the product life cycle period has accelerated implementation of decision making methodologies and frameworks encompassing sustainability aspects (such as environmental, social, and economic) into the design phase of the product development. Numerous tools have been developed using the frameworks which can be mainly classified into three categories: Eco-design tools, P-SPD tools, and SPD tools. Eco-design tools were commonly used during the early stage of development of SPD tools and were based on quantifying the impact on the environment caused by the products in each stage of its life cycle. P-SPD

Current tools and methodology for a sustainable product life cycle and design

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tools generally take into account the one of the two, i.e., social and economic, aspects along with the environmental aspect of product designing into its framework and since not all three aspects are taken, it cannot be considered as a complete SPD tools. SPD tools, however, take into consideration all three aspects of product life cycle into their framework, which brings in productivity, reduction in wastage, and maximum utilization of resources. In this paper, a framework for a multi-life cycle and multi-product-based circular system has been described in detail as proposed in [44]. A pricesensitive and time-varying bass diffusion demand model has been adopted which considers different EOL strategies for optimizing the conditions in environmental and economic aspects of the entire product life cycle.

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[34] UNEP, Guidelines for Social Life Cycle Assessment of Products, Life Cycle Initiative. United Nations Environment Programme (UNEP)?, Society of Environmental Toxicology and Chemistry (SETAC), Paris, 2009. [35] C. Benoıˆt, G.A. Norris, S. Valdivia, A. Ciroth, A. Moberg, U. Bos, S. Prakash, C. Ugaya, T. Beck, The guidelines for social life cycle assessment of products: just in time! Int. J. Life Cycle Assess. 15 (2010) 156–163. [36] A.D. Jayal, F. Badurdeen, O.W. Dillion Jr., I.S. Jawahir, Sustainable manufacturing: modeling and optimization challenges at the product, process and system levels, CIRP J. Manuf. Sci. Technol. 2 (3) (2010) 144–152. [37] R. Aydin, A. Brown, F. Badurdeen, W. Li, K. Rouch, S. Jawahir, Quantifying impacts of product return uncertainty on economic and environmental performances of product configuration design, J. Manuf. Syst. 48 (Part B) (2018) 3–11. [38] S.S. Gan, I.N. Pujawan, B. Suparno Widodo, Pricing decision model for new and remanufactured short-life cycle products with time-dependent demand, Oper. Res. Perspect. 2 (2015) 1–12. [39] J.M. Chen, C.I. Chang, Dynamic pricing for new and remanufactured products in a closed-loop supply chain, Int. J. Prod. Econ. 146 (2013) 153–160. [40] L. Cui, K.-J. Wu, M.-L. Tseng, Selecting a remanufacturing quality strategy based on consumer preferences, J. Clean. Prod. 161 (2017) 1308–1316. [41] M. Ameli, S. Mansour, A. Ahmadi-Javid, A multi-objective model for selecting design alternatives and end-of-life options under uncertainty: a sustainable approach, Resour. Conserv. Recycl. 109 (2016) 123–136. [42] M. Ameli, S. Mansour, A. Ahmadi-Javid, A simulation-optimization model for sustainable product design and efficient end-of-life management based on individual producer responsibility, Resour. Conserv. Recycl. 140 (2019) 246–258. [43] F. Badurdeen, R. Aydin, A. Brown, A multiple lifecycle-based approach to sustainable product configuration design, J. Clean. Prod. 200 (2018) 756–769. [44] R. Aydin, F. Badurdeen, Sustainable product line design considering a multi-lifecycle approach, Resour. Conserv. Recycl. 149 (2019) 727–737. [45] N.C. Petruzzi, M. Dada, Pricing and the newsvendor problem: a review with extensions, Oper. Res. 47 (2) (1999) 183–194. [46] A. Kocabiyikoglu, I. Popescu, An elasticity approach to the newsvendor with pricesensitive demand, Oper. Res. 59 (2) (2011) 301–312. [47] B. Robinson, C. Lakhani, Dynamic price models for new product planning, Manag. Sci. (10) (1975) 1113–1122. [48] D.C. Jain, R.C. Rao, Effect of price on the demand for durables: modelling, estimation, and findings, J. Bus. Econ. Stat. 8 (2) (1990) 163–170. [49] D.C. Schmittlein, V. Mahajan, Maximum likelihood estimation for an innovation diffusion model of new product acceptance, Market. Sci. 1 (1) (1982) 57–78. [50] V. Srinivasan, C.H. Mason, Nonlinear least squares estimation of new-product diffusion models, Market. Sci. 5 (2) (1986) 169–178. [51] V. Mahajan, E. Muller, F.M. Bass, New product diffusion models in marketing: a review and directions for research, J. Market. 54 (1990) 1–26.

CHAPTER TWO

Additive manufacturing for a dematerialized economy Jennifer Loy and James I. Novak Deakin University, Geelong, VIC, Australia

2.1 Introduction Forecasting is integral to sustainability research. Predicted levels of pollution [1, 2], for example, are frequently the basis for advocating changes in Government policy and company practices. While modelling highlights the outcomes of current trajectories, it needs to be supported by visions of alternative futures based on disruptions to current practices and mapped pathways to achieving those outcomes. Leading business management analyst, Peter Drucker [3], whose influential writing during the twentieth century contributed to the foundation of contemporary business practice, provided a forecasting framework based on three scenarios: the plausible— what is possible; the probable—what is likely, and the preferable—usually somewhere in between. His intention was to ensure that managers consider what could be possible, prior to predicting what was probable, and to build those opportunities into their proposals. One of the difficulties that has been found working with this approach is the challenge of projecting into a future where there has been a paradigm shift. In starting from the current situation and projecting forward, plans tend to be led by incremental change strategies, rather than based on disruptive change. Cameron [4] observed that the changes occurring with digital technology were too rapid and too radical for strategists to effectively comprehend, and therefore, the response to technologies such as artificial intelligence tended to be low-level integrations into practice, rather than maximizing its potential. Similarly, Gore [5] argued that changes in the 21st century would not be in degrees of difference, but in kind. The problems of understanding that reframing of practice are significant as it is inevitable that perceptions are colored by experience and projections build on existing practice. This chapter provides an opportunity to leapfrog the constraints of projecting forward from existing practice by, instead, proposing a situation Sustainable Manufacturing and Design https://doi.org/10.1016/B978-0-12-822124-2.00002-0

© 2021 Elsevier Ltd. All rights reserved.

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in the future where all the problems have been answered and a successful transition achieved. From this idealistic starting point, it is possible to then work backwards, to identify the key changes in attitude and practice that would be needed to reach that outcome. This method is termed ‘backcasting’. It was first proposed by Robinson [6] to help strategists “unlearn and rethink some traditional views” on forecasting. His view was that the wrong questions were being asked during forecasting, as predicting the future was not only “misguided (since we are usually wrong) but actually counterproductive” (p.1). He argued that there needed to be a shift from a focus on prediction to feasibility and the exploration of alternative futures. There has been a resurgence in its use recently by researchers on sustainability. According to Bibri and Krogstie [7] on using backcasting in generating proposals for smart, sustainable cities, “visionary images of a long-term future can stimulate an accelerated movement towards achieving the long-term goals of sustainability” (p. 1). Sustainability researchers are also looking to challenge current projections for future practice in high polluting industries, such as automotive [8, 9]. Global manufacturing practices are under increasing pressure to adopt sustainability strategies. However, incremental change is unlikely to be sufficient to significantly reduce their impacts on the environment. More radical strategies need to be considered. Additive manufacturing, commonly known as 3D printing, emerged as one of a suite of digital technologies that were developed during the digital revolution [10] during the last two decades of the 20th century and first two of the 21st. Additive manufacturing technically refers to seven families of digital fabrication technology that all build 3D models, layer by layer, from computer models without the need for tooling [11]. This contrasts with conventional manufacturing, where an up-front investment in tooling, such as moulds, is necessary. This facility radically changes what can be fabricated and has the potential to create significant disruption to business models. Yet, developments tend to be incremental in this space, with the technology predominantly used to augment existing production practices and supply chains. While this is a commercial decision in 2020, with the growing sustainability imperative for governments, societies, and the environment, arguably this should not be the case in the future. This is because additive manufacturing allows for print on-demand as the basis for a new business model that provides an alternative to mass production business conventions. In the sustainability context, additive manufacturing allows for value-added, invested products [12] over generic ones, supporting a shift from a throwaway society to one where products are designed bespoke and maintained.

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This approach reduces resource use and maximizes its value and reduces landfill. The economy in this case would need to be based on a dematerialized model. This requires a reframing of consumerism that is hard to perceive on a continuum of current economic models. To help explore what is feasible rather than predictable, this chapter uses backcasting to reimagine what could be possible, and then works backwards from there to identify key changes in attitude, behavior, technology, policy, and practice that would need to occur to reach it.

2.2 Welcome to 2040 Looking back to 2020, it is difficult to believe that the manufacturing practices and consumer behaviors that were prevalent at the time were acceptable. It was 20 years after the publication of such books as Natural Capitalism: The next industrial revolution [13], followed by Cradle to Cradle [14]. These highlighted the environmental problems brought about by the excessive sourcing of materials, the by-products of what are now considered unsafe manufacturing practices, and the pollution and waste in landfill and the oceans that do not decompose. Yet mainstream manufacturing practices remained relatively unchanged, the warnings and strategies identified in such books largely ignored. The leadership of companies such as Interface Carpets demonstrated what was possible, by shifting their business model from selling to leasing and their product from essentially single use to landfill, where it would not decompose, to a product designed for disassembly and the reclamation of materials for reuse. However, it took until the widespread changes in legislation introduced in 2021 for companies to seriously reevaluate their operations and respond to the sustainability imperative. Today in 2040, it is possible to objectively evaluate the impact of those changes in legislation and track the development of new ways of thinking and new ways of working that emerged over time. It is also possible to identify key moments in history where breakthroughs occurred that redirected practice for manufacturing and behaviors for consumers. Additive manufacturing and its cluster of enabling digital technologies has emerged as a key technology over the last 20 years after a slow development period during the first decades of the 21st century. It has proved to be the linchpin for a radical change in paradigm for not only the design and manufacture of products, but also the perception of those products as a whole, in their shift from transitory to enduring products.

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This chapter provides a description of the changed relationship of people to products and contrasts the ideology of manufacturing and product use now to that in use before the changes in legislation began 20 years ago. It highlights breakthrough events, ideas, products, and changes in practice that have occurred over the last 20 years and describes their role in changing the product zeitgeist. Without those changes, there would be no continuous products, and user behavior would still focus on consumption, rather than maintenance and renewal. This chapter documents those changes and provides a critical analysis of the leadership that achieved the current situation.

2.2.1 Background It was 20 years earlier than 2020 that triple bottom line accounting was initially identified as a critical component to business longevity with the change in thinking of societies on environmental impact: To refuse the challenge implied by the triple bottom line is to risk extinction. Nor are these simply issues for major transnational corporations: They will increasingly be forced to pass the pressure on down their supply chains, to smaller suppliers and contractors. These changes flow from a profound reshaping of society’s expectations and, as a result, of the local and global markets businesses serve. Anyone who has worked in this area for any time knows there are waves of change [15].

Authors, such as Hawken et al. [13], described how businesses would have to adapt to integrate sustainability strategies into their operations in order to remain relevant to a society that was becoming increasingly aware of the long-term effects of environmental impact by manufacturers. By 2007, the IPPC Fourth Assessment Report (AR4) by the United Nations Intergovernmental Panel on Climate Change was published, and manufacturers were forced to rethink practices. By 2020, environmental regulations and standards were in force to ensure that the impact of manufacturing on the environment was tracked and evaluated. The regulations referred to emissions, such as greenhouse gases, pollution, for example of water courses, and materials sent to landfill. However, companies were monitored through selftracking and reporting, which meant that there was an inconsistency in data supply and quality that would be less acceptable today, in 2040. The reliance on companies to be able to effectively self-monitor and their willingness to report problems that may have arisen at the time were understandably a concern for agencies such as the Environmental Protection Agency (EPA) in the US.

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In addition, there was a considerable level of complexity in comparing data from one facility to another to create a standard that could be used as the basis for identifying where excessive emissions occurred. This standard was then used to shape the advice given to companies on reduction and formed the basis for legislation on hazardous discharges, such as air pollutants. Reprocessing and resource recovery were part of legislation by 2020. For example, in Queensland, Australia, the Environmental Protection Regulation was enacted in 2019 to respond to community aspirations for improved waste management standards that reflected a shift towards the ideas of the circular economy that are now central to environmental standards in 2040. The Queensland 2019 schedule separated waste into moderate to high risk and nonregulated to low risk. The company disposing of waste and the receiving station were both required to track and report the activity to record the quantity and profile of waste sent to landfill. The emphasis in 2020 was on improving the monitoring systems for waste. However, it took considerably more legislation and a broader community understanding of environmental degradation to make significant shifts from monitoring to rethinking resource use in the circular economy of 2040. Arguably, the most significant legislation introduced during those early stages of change was on extended producer responsibility. At the time of its introduction, the impact of the legislation was small. It is only with hindsight that it is possible to track its evolution and understand its power in changing production and consumption practices. Its role in the rise of additive manufacturing and continuous products cannot be overstated, but it began with a limited scope, both in terms of the industries it affected and the products it applied to. However, it formed the basis for revolutionary changes to practice that informed the changes to thinking about product that emerged between 2020 and 2030. Designing sustainable countermeasures for addressing global warming requires an approach that unifies the various aspects of climate change, including impact assessment, prediction, mitigation and adaptation measures, policy issues, and social issues. It is essential to attack the problems from a wide range of viewpoints from different academic fields, including natural science, engineering, agriculture, economics, and political science ([16], p. 201).

Extended Producer Responsibility (EPR) first emerged in a policy approach in 1996 as a strategy for pollution prevention and control (OECD) after municipal waste increased an estimated 21% from 1988 to 1996. One of the problems with environmental tracking of resources and products

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through lifecycle assessment techniques invoked at the time was that once the product had left the retailer, there was no mechanism in place to track the use of that product or report on its disposal. Extended Producer Responsibility (EPR) policy stated that a product was the responsibility of the producer at the end of its useful life. Initially, this seemed a difficult, even unrealistic approach to legislate, and early products covered by the policy were limited, as was the geographical extent of the program. However, the OECD issued the book Extended Producer Responsibility: A guidance manual for Governments [17] under the auspices of the Working Party on National Environmental Policies, subsequently the Working Party on Resource Productivity and Waste. The policy was initially introduced in Europe, and one of the most significant industries to be affected was automotive. Vehicles were returned to the manufacturer at the end of life to be disposed of by the company. This created a financial incentive to redesign the cars to be partly disassembled, then essentially shredded and materials reclaimed through processes that separated out recyclable materials, such as metals. The reduction in waste sent to landfill was significant. This policy was extended to new consumer products wherever it was possible for European governments to enforce the policy or to provide incentives for companies to follow the practice, including electronic goods, batteries, and packaging. Yet, there was considerable resistance, and other countries, such as the US, were slow to adopt the practice [18] and the accumulation of waste in landfill in the US continued. According to Geyer, Jambeck, and Law [19]: 8300 million metric tons (Mt) of virgin plastics have been produced to date. As of 2015, approximately 6300 Mt. of plastic waste had been generated, around 9% of which had been recycled, 12% was incinerated, and 79% was accumulated in landfills or the natural environment. If current production and waste management trends continue, roughly 12,000 Mt. of plastic waste will be in landfills or in the natural environment by 2050 (p. 1).

In 2019, the US finally brought in EPR for packaging. This led to the introduction of reverse vending machines for glass, plastic, and aluminium drink containers, based on deposit schemes. It was not until years later, however, that the US finally introduced federal legislation for EPR to include vehicles, although they were early adopters with the National Vehicle Mercury Switch recovery program. Arguably, the US avoided its adoption until the manufacturing revolution of 2030, when the overwhelming impact of climate change and levels of pollution forced irrevocable change not perceived possible in the early decades of the 21st century. Policies from many

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other countries also extended pressure on the US, affecting imports and exports based on EPR policies that had global reach.

2.2.2 Continuous products The purpose of this chapter is not to dwell on the global wake-up call that was 2030 and the environmental disasters that precipitated it. There has been enough written about this time and the blinkered, short-term thinking that caused it. Suffice to say, there was a worldwide demand for reframing the relationship between people and products and the prioritizing of environmental responsibility over convenience and profit. Additive manufacturing, as a technology, matured at just the right time. Looking back, the whole basis for mass production was ideologically flawed. It depended on products designed to be generic, in order that they could be viably produced using tooling with high investment costs. By definition, the relationship between users and products could therefore only be superficial. Prior to the revolution of 2030, there was no Extended User Responsibility (EUR), and individuals could not be held liable for the maintenance and repair of their products. In 2040, this concept appears naive. Yet, as Fuad-Luke [20] discussed, attitudes towards sustainability and the products produced at a point in time need to be understood and evaluated within their context. During the second half of the 20th century, following World War 2, there was a global focus on economic growth in Western societies. It was during this time that ‘disposable’ products were promoted and products became increasingly difficult to repair, to the point where an attempt at repair could break the warranty on a product. By 2020, considerable research had been conducted on the Circular Economy, with the European Commission Circular Economy Action Plan [21] launched. This included the “right to repair” directive proposing the revision to European Union consumer law to ensure customers receive accurate lifespan information on a product, the availability of repair services, and “horizontal material rights” that allowed for spare parts and product upgrading. This formed the basis for the continuous product initiative. As a result, after the events of 2030, the framework for changing productto-person relationships were in place. The paradigm shift that occurred, where products were no longer seen as disposable, even after a considerable time in use, but rather as continuous, was able to occur not because the collective will was there. In addition, however, it was also because the appropriate technology was finally available to support it.

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2.2.3 Additive manufacturing personalized products The foundation for continuous product design was personalization. Up until around 2020, products were predominantly designed for a broad demographic, target market, or were designed to be customizable. That is, they were generic, but with options for the user to make changes, for example, to color, material, or finish. These changes were usually limited and constrained by the parameters created by the designer [22, 23]. For mass produced products, even those customizable were not personalized. That is, they were manufactured without specific information pertinent to the user. Additive manufacturing essentially began as a prototyping technology, although even its earliest forms were translatable into end-use products for a small number of medical applications, such as skull repair. It was originally resin-based, called Stereolithography, and it was predominantly used for visualization. The term additive manufacturing was then applied to an increasingly large number of techniques and technologies, which all involved building material in layers to create a three-dimensional product without the use of conventional tooling, such as moulds. By 2020, there were seven families of additive manufacturing, commonly known by then as 3D printing, that included a myriad of different 3D printing technologies. A wide range of materials were able to be printed into functional parts, including titanium, aluminium, steel, nylon, ABS, PLA, glass, and ceramic. While the technology matured from prototyping to functional applications in the decade prior to 2020, its impact on the consumer market did not occur until the manufacturing revolution of 2030, when the green agenda, outlined by the European Union, was adopted globally in response to the environmental challenges at that time. Once EUR was brought in, and individuals were responsible for the maintenance and repair of their products, and producers incentivized to produce personalized products, there was a demand for technology that could fabricate bespoke parts. Additive manufacturing had developed sufficiently over the previous decade to be ready to rise to the challenge. As people were no longer able to buy and discard mass-produced products, but instead restricted to buying single products only after considerable justification and expense, the emphasis on disposability shifted. Products that were intended to be kept indefinitely required more thought and had more perceived value when created specifically for the individual. Prior to the introduction of additive manufacturing, this was not financially possible. 3D printing enabled the paradigm shift for

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society from viewing products as detached from the individual to extensions of the individual. Where this approach had been evident in design for disability, for example in the expressive prosthetics by the UK company Alternative Limbs, it had not been prevalent in mainstream products. Additive manufacturing was available at the right time, when the demand for personalized products became universal.

2.2.4 Additive manufacturing adaptable products The natural extension to the right to repair strategy was the right to adapt. This initiative built on the right to repair charters, by ensuring that not only was it possible to adapt products more easily, without voiding warranties, it was also a requirement for designers and producers to design products for adaption. In addition, just as in the early days of EPR in the US, companies had been required to provide facilities and schemes to support the return of products after use, so too were companies obliged to foster the relationship of people to product by facilitating adaptability facilities and schemes. Again, additive manufacturing had matured as if with foresight, with the FabLab initiative of Neil Gershenfeld. Gershenfeld had established the first FabLabs in 2001, beginning at MIT, before branching out into the community of Boston as a workshop that allowed the public to access digital fabrication technologies, including 3D printing [24]. The Fab Labs also provided education and support for individuals on 3D printing. By 2020, Fab Labs have been opened around the world. 3D printing was the core technology they were built on. In addition, the sharing of 3D files for 3D printing online expanded rapidly between 2010, when the first 3D printing online service providers were launched, and 2020 [25]. As a result, a maker society had matured alongside the technology, with attitudes towards making aligned with the “right to repair” movement. Without additive manufacturing, the paradigm shift towards viewing products as adaptable, continuous products that were value-added (that is, they contained in their design and fabrication social constructs that added value for the user, described by Walker [12] as invested products) would have been much more difficult, if not impossible in a commercial context. Additive manufacturing provided the bridge between an economy driven by double bottom line accounting, to one based on triple bottom line accounting. Additive manufacturing formed the basis for a more viable dematerialization of the economy.

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2.3 Additive manufacturing for a dematerialized economy According to Ryan [26], for an environmentally sustainable economy to be financially viable, it had to pivot towards six key sustainability principles. Ryan argued that these principles framed an action plan for sustainable development. The principles were: • Valuing prevention • Preserving and restoring “natural capital” • Life cycle thinking (closing system cycles) • Increasing “eco-efficiency” by “factor x” • Decarbonizing and dematerializing the economy • Focusing on design—of products and product service Sadly, these principles were not the driving force behind the development of additive manufacturing, and additive manufacturing did not mature into a viable set of production technologies until about 15 years after these principles were written, yet the technology could have been developed directly in response to several of their directives. Additive manufacturing (AM) is considered to be promising for sustainable production because the additive and digital nature provides opportunities to save resources. This additive and digital nature enables, for instance, on-demand production of spare parts for repair…or avoids material losses when compared to subtractive technologies such as milling ([27], p. 1138).

To begin with, additive manufacturing maximizes the use of materials. This is because high value, complex products are fabricated on demand, over massproduced products built en masse in the hope of being sold. Centralized mass production practices are replaced with distributed manufacturing, and the design of high-value products, and in particular the development of product service systems, helped to shift consumerism towards a dematerialized economy.

2.3.1 Distributed manufacturing 2040 Today, in 2040, additive manufacturing is ubiquitous; most city suburbs will have at least one digital manufacturing center with a front-facing store open to the public and a back-facing production zone where both local and networked products are farmed to 3D printers for manufacture. Some regions have become famous for their ability to produce objects from a

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locally sourced material, giving a unique identity to these areas and the products manufactured in them. All children learn virtual design and coding skills in school, and gaining employment in the manufacturing industry is competitive and lucrative, especially for those who become certified by one of the major manufacturing hubs, with large bonuses for products that make it to the 10-year milestone. The days of fast fashion and products with planned obsolescence are difficult to imagine, as are towns and cities without any source of manufacturing. While the system works well today, distributed manufacturing was slow to materialize through the early decades of the 21st century, as shown in Fig. 2.1. The desktop 3D printing revolution was meant to herald a new manufacturing revolution, one in which the tools of production were accessible to all. This began with the RepRap project [28], an open source 3D printer capable of producing many of the parts necessary to build a copy of itself. Numerous permutations of this 3D printer emerged between 2010 and 2020, supported by large online libraries of files that rivalled the size of mainstream knowledge communities [25], and while traditional manufacturers began to take notice of this trend, as pointed out by Krywko [29], p. 1 “factories are like supertankers in a way. They are huge but it takes ages to get them up to speed, to slow them down, and to change their course.” While additive manufacturing found niche industries ripe for transformation, in general, it was seen as a distraction from the primary business of making money for shareholders. Contrastingly, today centralized mass manufacturing is niche, and most of it is automated, from the refining of raw materials, through to operation and maintenance, and much of the supply chain. Very few people are required to keep the systems operating. Most of the products that people value and engage with in meaningful ways are part of digital systems and not something bought in a store. This is akin to some of the early researches into “prosumers” [30, 31]; however, with the distinct difference being that people do not themselves produce goods. While prosumerism was a novel concept aligned with early interest in desktop 3D printing, the reality that emerged during 2020–2030 after decades of development was that the technology just wasn’t aligned with how people lived in the home, or how people wanted to spend their time. The burden of machine maintenance, combined with a breadth of system and brand choices that confused people, as well as a lack of an economic system supporting people to manufacture goods at home, meant that the case for prosumers fell apart.

Fig. 2.1 Backcasting additive manufacturing timeline.

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However, what people did want, and is now assimilated into everyday practice in 2040, was initially imagined more holistically in literature related to ubiquitous computing, in particular, the idea that computing would be seamlessly integrated into everyday life, as predicted by Weiser [32] and discussed in the current and future context by Greenfield [33, 34]. Through the 2010s, people increasingly adopted early generation wearable technologies and the home became connected to the Internet, allowing people to use their voice or mobile phone to control lighting, appliances, and other electronic gizmos. Through the 2020s, these devices became more autonomous, integrating artificial intelligence better able to predict user needs, and into the 2030s, almost all products gained some level of computation and connection. This has led to the realization of responsive design systems [35], collating vast amounts of data about individuals and predetermining product needs. The real leap for additive manufacturing in the 2030s was combining the knowledge about an individual with the ability to manufacture goods for them in advance of their need, delivered just-in-time by a local manufacturing hub. This included computing and sensing technology that could continuously self-update software and adapt behaviors via the Internet, with hardware updates plateauing during the early 2030s and all but negating the need for replacing complete electronic systems. Modularity became the new standard and Moore’s Law had finally run its course. One of the innovations that really helped manufacturing hubs thrive was the ability to “swap ‘n’ go” certified products. The process typically follows the process below: 1. The computation within a product alerts the user a swap “n” go is necessary. This may be in response to changes in the user (e.g., body geometry or functional requirement), designer upgrades to the product, or a need for a repair. 2. Simultaneously, this information is used to schedule 3D printing of a new product within a local manufacturing hub. Any design changes are integrated automatically through parametric capabilities of a certified swap ‘n’ go product. 3. When a user visits the swap “n” go provider, the electronics module is transferred to the new one, and the product is swapped. The user leaves with an updated product. 4. The old product is separated into material components and broken down to be used as feedstock for the 3D printers. Very little is wasted or thrown away.

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A product that lives on through 10 years of this type of adaptation and continuous use is gold-certified, and the designer is typically rewarded a significant financial bonus through the relevant collective community. This is in recognition of the continuous improvement brought to the product over this lifetime, enabled by the potential of the original design. Complex systems to adapt products beyond the initial imaginings of the designer support this culture of adaptation, and users may also gain financial benefits by having adaptations certified and built into the product system. This is a quite different process and approach for the designer compared to even a decade ago where quantity dominated thinking, with a race to the bottom for wages and product price the result. Distributed hubs also began to transform the household recycling system, increasingly accepting materials from packaging and mass-manufactured goods to be used as feedstock for 3D printers, alongside products returned under the swap “n” go system. While in the 2010–2020s countries like Australia struggled to deal with recycling programs, having limited local systems and relying on countries like China to accept waste materials for recycling [36], with the rise of suburban manufacturing hubs and new technologies to convert products into feedstock in an efficient manner, a win-win situation emerged for the hubs; they were able to increasingly accept local community materials formally collected as part of a large recycling supply chain, and therefore, reduce their costs in purchasing virgin materials to manufacture new goods. This started to close the loop for additive manufacturing, and while the system today in 2040 is still not perfect, the localization of both production and recycling has had a huge impact on the environment and the community awareness of material value. The system today is diagrammatically shown in Fig. 2.2, which includes the swap “n” go system. This dematerialization of the economy was also attributed to changing consumer demands and the shift during the early 21st century to a knowledge economy. Between 2010 and 2020, major industries like film, television, and music shifted from physical products to digital bits of information that could be accessed and streamed by anyone, anytime, via the Internet [37, 38]. This started a chain of events where increasing numbers of products and systems became digital and consumers expected almost everything to be accessible on-demand. This included smart and connected products, which consumers wanted to trial, purchase, upgrade, and modify from the comfort of their homes. This extended the online shopping trends of the time and required designers, engineers, and manufacturers to shift the focus of their efforts from the physical production of a product to the extended

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Fig. 2.2 2040 closed loop system for community production and recycling.

responsibility to allow that product to adapt to the needs of each user, over increasing lengths of time. While in 2040 the ability to provide new products directly into the home does not appear to be of interest for all but the most serious of makers—who continue to push 3D printing technology and gain recognition through certification of adaptations—the distribution of high-end manufacturing hubs within the community has been implemented and integrated into practice. Hubs provide the latest manufacturing technology and take care of the challenging maintenance, repair, and monitoring tasks that have always been associated with manufacturing. They also mean that products ordered ondemand by a customer can be collected from within their own locality, or delivered by an Unmanned Aerial Vehicle (UAV)—demonstrated to reduce greenhouse gas emissions 20 years ago [39] and increasingly used since that time. As a result, there has been a two-fold impact on the supply chain: Firstly, with a reduced supply chain, customers are able to experience close to on-demand production of goods that are specific to their needs. Frustrations from the 2020s about closed borders and struggling global systems of supply are now rarely a concern. Secondly, the demand for new physical goods has also declined. As products have become increasingly

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personal, the perceived value of these products has increased. People do not want to throw away or replace these products, and new functionality is frequently possible through systems upgrades, as well as repair or upgrade through a “swap ‘n’ go” provider.

2.3.2 Key turning points 2030 With reference to the literature review, it is found that most AM technologies are more sustainable than conventional manufacturing regarding lesser environmental impact, process emissions, resource consumption, and energy consumption ([40], p. 1053).

Additive manufacturing in 2040 is central to the triple bottom line, sustainability-based economics now an established policy across the majority of countries. It is integral to the continuous product approach that emerged from the right to repair legislation that had its foundations in the 2020 EU green agenda, and the introduction of Extended User Responsibility (EUR) introduced not long after, with its emphasis on personal responsibility. From a historical perspective, it is interesting to track the shift in public perception of products from static objects to adaptive products, viewed as companion to life, rather than consumed during life. This shift had been driven by the market in response to the growing awareness by stakeholders of the need to rethink the drivers behind the economy in order to reduce the environmental impact of an economy based on conventional consumerism. The traditional roles of design, designer, and designed object are thus refined through new understandings of the relationship between the material and immaterial aspects of design, where the design product and process are understood as embodiments of ideas, values, and beliefs. This notion brings to the fore central questions around social responsibility, sustainability, and consideration for the life of the object beyond the design studio ([41], p. 3).

In 2020, the global Covid-19 pandemic created the conditions—and collective will—for radical changes to the organization of production, distribution, consumption, and disposal of product. With the closing of international borders, and restrictions on the flow of goods, the preservation of material value and the need for the re-localization of manufacturing were raised dramatically. In this context, products were redesigned to be retained over long periods, actively enabling repair and maintenance that had previously been discouraged by restrictive warranty conditions. To support the

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necessity of monetary exchange for a financial economy, value was shifted into embodied cultural expression indicators. This practical shift aligned with the cultural shift seen by forecasters such as Hajkowicz [42]. Hajkowicz defined sustainability megatrends in 2015 of Planetary Pushback, and More from Less and the widespread adoption of digital communication technology, he termed Digital Immersion. Additive manufacturing, used as a print-ondemand facility or as a way of value-adding to resource use by creating meaningful products [43] through personalization, emerged as a timely option over the next decade. This technology also responded to other megatrends identified by Hajkowicz at the time, such as Great Expectations, where customers demanded more from all products, supporting the initial cultural shift to value-added product service systems over stand-alone products. Looking back to 2030, as indicated in the Fig. 2.1 timeline, this was a key turning point in design history, as the number of companies responding to the growing public expectation of product service systems over stand-alone products outnumbered those that did not. By 2033, it had widespread adoption as standard practice. The early manifestations of product service systems had companies moving from selling to leasing products [13], and digital technologies being demonstrated to track products during use, for example to anticipate and respond to the need for spare parts (Design Museum exhibition). By 2018, tracking technology and data analysis was the accepted practice. Sensor technology had reduced price and was increasingly integrated into products. A significant example was in the automotive industry, where sensors tracked both the performance of components of the car and the overall performance of the engine. In addition, apps in 2020 provided customers with driver performance data, while companies had access to destination mapping data and patterns of movement. The development of data analytics capabilities and the rise of artificial intelligence and machine learning changed the perception of manufacturers as products were no longer seen as individual, static objects, but as contributing to a ‘macro-product’ design that was informed by the behavior of the micro-level components (individual products) of that macro-product as a whole. In 2030, a study of marketing at that time showed that there was a shift in sales rhetoric from product, to product service system. Consumers no longer sold products for the life of the product, but rather leased products over an extended period of years, supported by warranties and service agreements much like vehicles. In response to this new characterization of product, designers increasingly turned to adaptive personalization as the foundation for their work.

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For product personalization to an individual’s specific needs on a mass scale, including ergonomics and esthetic preferences, production had to be based on manufacturing that required no up-front investment in tooling, such as moulds. It also had to be completely digital. The maturing of additive manufacturing for functional, bespoke products between 2020 and 2030 allowed companies to change their business models to accommodate the new market environment. From 1960 to 2016, the average lifespan of businesses reduced from 60 years to 10 years. Digital technology changed business practice and competition as the Internet expanded: The contemporary digital revolution will have profound effects on both business and society at large. According to a World Economic Forum study (WEF 2017), the cumulative value at stake amounts to more than 100 trillion USD for the decade running from 2016 through 2025. Recent announcements confirm the dominance and disruptive potential of digital technology companies. As of 1 August 2016, the five largest US firms by market capitalization are all digital technology companies….Moreover, there are nearly 200 digital ‘unicorns’, i.e., private start-up companies with market capitalization of at least 1 billion USD as of the end of May 2017….These digital start-ups have disrupted traditional industries dramatically: examples include Netflix (video distribution/rental), Uber (passenger transportation), and Airbnb (lodging) ([44], p.1).

From 2020, that trend continued, with micro-business models embracing the distributed manufacturing model, enabled by expansive digital communication technology. Product service systems were created that were populated with digitally enabled products within the Smart City agenda built in the decade between 2010 and 2020 and were integral to life in 2030, albeit expressed more inclusively and appropriately as the Smart Community agenda by then. The Smart Community agenda has integrated a connective electronic Internet of Things (IoT) into rural, regional, and urban areas to collect data to inform the management of services and assets. The early definition of Smart Cities [45] included the use of Information Communication Technologies (ICT) to transform life and working conditions in a region and the “territorialization of such practices in a way that bring ICTs and people together, so as to enhance the innovation, learning, knowledge and problem solving which they offer” (p. 3). Following the COVID-19 pandemic, there was a reruralization in countries such as Australia, where there had been a growing, unsustainable imbalance between populations in urban centers, such as

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Sydney and Melbourne, and regional and rural locations. This redistribution of the population was enabled by digital technology that allowed for a distributed workforce, not possible in the previous century. It took global health and well-being challenges to trigger a widespread change in attitude by companies to the concept of working anywhere [46], as well as the Government investment in appropriate infrastructure in 2024 to support it. However, once adopted, the impacts of those changes had unexpected consequences that were recognized formally in the Global Health Report 2030. By 2030, the effects of shifting from centralized working practices, including manufacturing, to distributed manufacturing could be identified and were measurable. As evident even during the outbreak of COVID19 in 2020, the dispersal of concentrated populations, reducing the necessity for populations to commute, had a significant impact on air quality. In China, South Korea, Italy, and the UK, for example, levels of nitrogen dioxide pollution caused by burning fossil fuels were significantly lower over major cities than during the same period the previous year [47]. Reducing this pollutant had health benefits for individuals with asthma, and the effects quickly became fundamental to new policies implemented after the pandemic. Long-term, the move towards distributed working practices radically reduced commuting and, as a consequence, air pollution. In addition, however, it was concluded in Global Health Report 2030 that the health and well-being of populations overall improved. This was attributed to factors such as a reduction in the spread of disease, a reduction in stress levels in the population as a whole with the removal of the morning and evening commute, and an increased identification with local communities. The report concluded that the mechanisms and digital platforms and working practices developed during the pandemic had provided the foundation for future practice. Meanwhile, from an economic point of view, the dispersal of populations brought housing prices in cities for those remaining to manageable levels, reducing cases of loan defaults and family stresses. The cost of maintaining the infrastructure, such as road and public transport services, to service cities not designed for the expanding populations of 2019 was reduced. The investment of community members in local area networks established what were future working practices, now long established. Societies have progressed since the problematic trial of a Universal Basic Income in Canada in 2018 [48]. The utopian tenets discussed by Bregman [49], which proved unrealistic in Canada in 2018, could be deemed more relevant and less idealistic during the lockdown of cities in 2020 [50].

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2.4 Starting points 2020 There is a clear consensus that the future now emerging will be extremely different from anything we have ever known in the past. It is a difference not of degree but of kind [5].

The intention in this chapter was to work backwards from a vision of the future that proposes a different way of living, enabled by maturing digital technologies, unhampered by current constraints. In the scenario posited in this chapter, technological developments combine with world events and megatrends in societies to disrupt current practice and behavior. By 2040 in this scenario, distributed working is integral to society, and economies have adapted to values and commercial interactions aligned with a dematerialized economy. In this utopian ideal, populations are more dispersed and local communities are digitally connected and engaged, yet empowered and territorial. Individuals are healthier and happier, and the negative impacts of people on the environmental health of the planet are reduced. Crucially, attitudes have undergone a radical restructuring, and sustainability as societal, environmental, and economic has replaced the purely economic. Significant changes would be necessary between now and then to reframe societal priorities and redirect policy towards building a different future, where commuting was largely obsolete and the resources invested in a product were appropriately valued. In this scenario, consumerism would be tempered by a focus on localized production and the ability for communities to maintain and repair products. Products themselves would have greater inherent value because they would be personalized to the user, and they would be designed to adapt and change over time as a way to retain their connection to the user and also enable commercial practice in an essentially dematerialized economy. Based on the 2030 stage of this scenario, an ecosystem needs to be developed to support the 2040 vision. This ecosystem involves stakeholders from design and engineering and manufacturing, but equally needs to be populated with stakeholders from across society, from users to Government policy makers. An approach as suggested here requires changes in community engagement, distribution, infrastructure development, and models of commercial interaction for personalization. In short, it involves creating a whole

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new ecosystem, based on very different principles of thinking, different aspirations for society built on social and environmental sustainability, and aspirations for a smart, community-based society. In 2020, digital technologies have evolved to a suite of interconnected tools that allow very new ways of operating as a society. In 2001, [51], the director of the Center for Bits and Atoms at MIT, launched the first Fab Lab, a facility where members of the public could access advanced, but accessible, digital and electronic technology, such as 3D printers (the common term for additive manufacturing). While additive manufacturing moved from research labs and academic initiatives to the public domain, Aldersey-Williams [52] argued that the technology freed individuals from the constraints imposed by the industrial revolution and would provide the opportunity for a return to a way of life where localized, bespoke production complemented small community living. Anderson [53] described this shift as imminent, as low-cost, desktop 3D printing provided the basis for a democratization of making. At the same time, Atkinson [54] was describing a groundswell in the democratization in the control of labor, through the development of digital communication tools. Yet in 2020, 3D printing has not created Aldersey-Williams [52] revolution in working practice and a return to village life. The reasons are twofold: Firstly, because the changes to society needed for a redirection of the trajectory of Industry 4.0 are so comprehensive, there is a shortage of sustainability research in this area [55]. Secondly, there was a disconnect between what was possible to fabricate using a low-cost desktop 3D printer, costing less than $800, and industry-level 3D printers, which can cost over a million dollars, depending on the materials to be printed and the technology used. For the general public and also for many companies considering the technology, this miscommunication created a sense of disillusionment that has to be counteracted by more focus on informed education [56]. There is an argument that this should be accepted as the result of natural market forces. However, there has been a recent rise in concern about the impact of product manufacturing on the environment, even if driven by profit risk mitigation [57], with the growing sustainability imperative. Consumer expectations and the drive towards the adoption of circular economy strategies are gradually changing practice, but not with speed. However, the European Commission Circular Economy Action Plan outlines the development of an ecosystem approach to manufacturing. In addition, there is a confluence of digital technologies

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that provide the opportunity for new ways of working that could disrupt conventional businesses already under pressure to respond to the very different ways of working possible with digital technology. Perhaps even more significant are the alternative futures suggested by the global pandemic in 2020, which illustrates how dramatically established practices, formerly considered unassailable, can be disrupted. The transition to new ways of thinking, of working, of making, and of interacting with products over their lifespan and to respond to manufacturing in context aligned to aspirations for society at this time requires considerable research. From the literature study, it is found that a lot of research is being done on AM, but only a little research is focused on the societal impact associated with additive manufacturing ([40], p. 1).

2.4.1 Transition research The intention of this backcasting evocation was to disrupt incremental thinking about the adoption of additive manufacturing merely into the palette of conventional manufacturing technologies available. Additive manufacturing and its associated digital sensing, networking, and data analysis technologies allow for a reframing of commercial interaction and entrepreneurship. It also allows for a reevaluation of material use in products and suggests a shift in perceived value from low-cost, generic products with built-in obsolescence towards products that are of high value, personalized, and retain their value over time. The perception of these products would be that they were a long-term investment, potentially even a lifetime investment, changing the relationship between people and products. More than that, the design and fabrication of these products would be embedded in community practice, visible and accountable, rather than hidden and difficult to account. As utopian as this proposal may appear to be striving to be, as Robinson [6] argued, without contemplating alternative futures, it may not be possible to break development out of conventional tracks. While a business as usual approach may have been acceptable previously, where profit was the measure of success, in the 21st century, the sustainability imperative requires alternative behaviors, attitudes, and practice [58]. Additive manufacturing allows for significantly more sustainable, user-centered approach, where localized manufacturing, high-value bespoke products, and cultural, digital value-adding contribute to a dematerialized economic model.

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In order to reach the milestones and desirable future state outlined in this chapter, transition research is recommended. Transition research is emerging from its roots as providing an objective, historical perspective on a period of change, to one engaging with an anticipated disruption, to track its impact in real time across multilevel stakeholders. According to Zolfagharian et al. [59], p. 1: A transition involves far-reaching structural changes in socio-technical systems that enable particular desirable societal functions (e.g., mobility, energy, healthcare). In this respect, transitions are multi-dimensional processes that often include technological, material, organizational, institutional, political, economic, and sociocultural changes. As such, transitions typically involve a broad range of actors (e.g., individuals, firms and organizations, and collective actors), institutions (e.g., societal and technical norms, regulations, standards of good practice), and technological elements (e.g., material artifacts and knowledge).

Such research is broad and involves complex networks; however, it is necessary in order to shift sustainability measures, and in particular, manufacturing processes. For transition research engaged in intervention, the work can be based on an Action Research methodology [60, 61]. The pace of changes in 2020 and beyond is such that transition research based on intervention is needed to provide manufacturers with support in responding to the changes happening around them. In addition, more transition research that tracks and then tries to understand changes happening in one company, and how the findings could be generalized for other companies, is needed. Where transition research is used to support established companies, crosssectional research may need to be employed to provide problem framing and complex systems thinking. To integrate additive manufacturing and emerging digital technologies into existing practice, researchers need not only know about the technology, but new business models, supply chain management, and organization, as well as the education of future generations which will provide the workforce for new and restructured businesses [62]. Within academia in 2020, this is rarely the case with researchers based in specific disciplines and schools due to the longstanding silos established within institutions. Collaboration across specializations will be essential for reaching the hypothetical 2040 ideal state, requiring new ways of thinking and working, as well as new academic models that better value transition research and other methods that require researchers to operate outside of their borders. The implications need to be modelled, tracked, and evaluated through the lens of different

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disciplines. Ambitious, cross-disciplinary research is necessary to provide insight into the unseen implications of innovation in manufacturing, and additive manufacturing provides the catalyst for significant change.

2.5 Conclusion During the last 2 years, a considerable amount of literature has been published on the use of backcasting in sustainability research. This could be because the alternative futures that need to be proposed to make significant change require complex, interconnected, radical thinking to enact. This method allows an initial freedom to propose an alternative, then work backwards to test the reality of the proposition, identify where, why, and when change will need to occur. With additive manufacturing, there is the potential for it to demonstrate new ways of distributed working, contributing to modelling a more sustainable future. It allows for a reset of the relationship of people to products, dismantling the values for a throwaway society that were promoted in America following the second world war in order to stimulate the flagging economy [63] and dominate current consumerism. There are challenges, however, in reframing the issues involved for the sustainability context. There is a need to provide strategies for changing practice, priorities, policy, and attitude sufficiently to disrupt current trajectories. The experience of Detroit [64] provides a good example of how the disruption to an expected economic trajectory can change radically the way business is conducted, the values of the community, and the policy of its leaders. For new visions of a more sustainable future to be realized, they need to be imagined. These need to be interrogated to ensure that the future being worked towards is actually beneficial across societies and sustainable for the environment long-term. There then needs to be concerted backtracking by interdisciplinary stakeholders to map the development of a supporting ecosystem. Only then can the first steps in a new direction be made.

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CHAPTER THREE

Sustainable friction stir welding of metals U. Sudhakara and J. Srinivasb a

SCSVMV University, Kanchipuram, India Mechanical Engineering, NIT Rourkela, Rourkela, India

b

3.1 Introduction Aluminum, copper, zinc, and magnesium alloys have widespread use in industries over the last two decades due to their lightweight and good mechanical characteristics. Mechanical, electrical, and thermal properties of these materials have attracted them in applications like body covers, cylindrical vessels, and as alternative structures made up of steel and other ferrous metals. Especially, aluminum has multiple roles in daily life and industries. Different series of wrought aluminum alloys have been in use for different applications. Joining of different such materials is inevitable in producing the sheets of required length. The common techniques for joining aluminum alloys or other metallic/alloy sheets or plates are fusion welding approaches like gas welding, brazing [1], and electric resistance welding [2]. For welding aluminum and its alloys, gas welding is also not recommended as the oxide layer is formed while solidifying within the weld zone. In fusion welding techniques, the work materials are melted and have large heat-affected zone resulting in high residual stresses along with release of huge amount of flumes. With the changing environmental scenario, several pollution control norms were introduced and the concepts of green manufacturing and eco-friendly production systems have huge impact on the modern industries. In this line, digital manufacturing and friction stir welding are some techniques that came into existence. Friction stir welding (FSW) was first introduced by the welding institute in UK in the year 1991 [3], and later on, it has several variants including friction stir processing, spot welding, lap welding, T-welding, etc. [4]. In FSW, a nonconsumable rotating tool at high rotational speed is plunged into the joint region of workpieces to be welded and moved along the weld line with constant velocity. The friction heat generated softens the Sustainable Manufacturing and Design https://doi.org/10.1016/B978-0-12-822124-2.00003-2

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metals to their plastic state. By advancing the tool forward, the softened metal around the tool gets cooled by moving in backward fashion. Thus, the plastic deformation generates heat, resulting in 90% solidification temperature. The weld region can be divided into four zones: (1) base material, which is not affected by plastic deformation; (2) heat-affected zone (HAZ); (3) thermomechanically affected zone (TMAZ), where no recrystallization is observed due to insufficient heat, but several grains are noticed; (4) stir zone (SZ) which is characterized by fine grain structure due to severe plastic deformation. Over the last two decades, several studies focused on the concept of sustainability in friction stir welding of various metals and alloys. Cam and Ipekoglu [5] in their work reported the developments of aluminum alloy welds. Cole et al. [6] employed dissimilar 6061-T6 and 7075-T6 aluminum alloy welds to illustrate effect of weld parameters including tool offset on the joint quality. Zhang et al. [7] considered shoulder concavity angle effect on friction stir welding of 5052 aluminum alloy characteristics including applied force, nugget width, etc. Juarez et al. [8] illustrated the effect of bolt-head pin profile tool on the mechanical properties and flow characteristics of friction stir-welded AA6061 ¼ T6aluminum alloy. Daniolos and Pantelis [9] studied similar and dissimilar 6 mm thick AA6082 and AA7075 butt welds. Microhardness and microstructural investigation at weld zone revealed recrystallization occurrence at heat-affected zone. Fractography was also conducted for tensile-tested samples. Safen et al. [10] predicted ultimate strength, impact toughness, and hardness of AA6061 aluminum alloy friction stirwelded joints by varying process parameters and tool-pin profiles. Tang and Shen [11] studied the temperature distribution in lap friction stir welding of dissimilar aluminum alloys AA2024 and AA7075. Both experimental and numerical studies illustrated the different temperature distributions due to different material properties. Liu et al. [12] presented friction stir welding of aluminum alloy AA6061-T6511 with TRIP 780 steel at different process parameters. Two different tools were used for understanding material flow ability via computer tomography. AbdElnabi et al. [13] studied the effect of seven process parameters on the ultimate strength and ductility of friction stir-welded AA5454-AA7075 aluminum alloy plates. Friction stir welding is one of the sustainable machining processes. In comparison with available welding techniques, FSW consumes less power and minimizes the release of hazardous gases. The economic aspects of sustainability include high productivity, minimum production cost, and lead times, while the environmental aspects are reduced tool wear and alternative methods to release poisonous gases. Finally, social aspect of sustainability

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refers to relationship between customer and manufacturer (improved work quality). Bevilacqua et al. [14] illustrated the effect of tool rotation and weld speed on the output energy and emissions in a butt welding of AA5754 aluminum alloy sheets. Finally, the effect was shown on the ultimate tensile strength and elongation of the joint. Azeez et al. [15,16] presented the effects of post-heat treatment of friction stir-welded AA6082 plates at different tool rotations and weld speeds and increase in ultimate tensile strength was noticed. As traverse speed increases, the reliability of weld joints reduced drastically. Multiple factors are, therefore, required for assessment of joint reliability and hence process sustainability. In this chapter, a framework of fabrication for different butt welding joints of aluminum alloys AA5251 and AA6063 plates is presented by varying the weld speed and tool rotation. The butt-welded plates are transversely cut as tensile and impact testing samples. Theoretical input power calculations are presented and the neural network model is developed to obtain the functional relationship between input parameters and outputs. The rest of the chapter is organized in the following sections: Section 3.2 deals with the materials and manufacturing along with output analysis. Section 3.3 provides some mathematical calculations for power input in terms of tool and material data. Section 3.4 gives results and discussion.

3.2 Materials and experimental work Wrought aluminum alloys have wide range of applications in industries [17]. Especially, 5xxx and 6xxx series of alloys are known for their corrosion resistance and fatigue strength. In present task, it is planned to study the friction stir welding of dissimilar aluminum alloys AA5251 and AA6063 to understand the economics of the process. AA5251 alloy is used in panelling and pressings, marine and aircraft structures, while the alloy AA6063 is employed in rail-road transportation and as a sporting material. The material compositions of these alloys are given in Table 3.1.

Table 3.1 Chemical compositions (%wt) of the studied alloys. Alloy Si Fe Cu Mn Mg Zn Ti

Cr

Al

AA5251 0.4 0.5 0.15 0.1–0.5 1.7–2.4 0.15 0.15 0.15 Balance AA6063 0.2–0.6 0–0.35 0–0.1 0–0.1 0.45–0.9 0–0.1 0–0.1 0.1 max Balance

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52 Table 3.2 Properties of base materials at room temperature. Property AA5251

AA6063

Ultimate tensile strength (MPa) Elastic modulus (GPa) Thermal conductivity (W/m°K) Thermal expansion coefficient

90 70–80 218 23.4  106/°K

160–200 70 134 25  106/°K

The mechanical and thermal properties of both these materials are listed in Table 3.2. The plates are first cut into pieces of size 100 mm (length)  50 mm (width), each having a thickness of 5 mm. The joints are fabricated with the use of a column and knee type vertical milling machine in single pass operation using a specially prepared cylindrical HS tool H13. Friction stir welding tool has three zones: (i) holding region, (ii) shoulder, and (iii) pin. Pin region completely digs into the junction of two weld plates, which are held tightly without separation. Underneath portion of the shoulder often touches the top surfaces of two weld plates. In order to plasticize the material at the required axial pressure, different types of pins like threaded, tapered, and cylindrical with various types of head profiles as well as conical edge shoulders are employed. The depth of pin is also an important factor. Tools with four different pin depths are considered as shown in Fig. 3.1. Tools having 9 mm shoulder diameter and 24 mm shoulder length with a straight cylindrical pin having square headed section of 3 mm sides are employed. After a short dwell time, the tool is moved forward along the joint line at the preset welding speed. The schematic representation of FSW process is shown below in Fig. 3.2A, while practical setup for fixing pair of workpieces is given in Fig. 3.2B. A mild steel plate of 25 mm thick is used as backing support material under the weld joint inside the fixture. In all experiments, AA6061 plates are kept on the advancing side (AS) and AA5251 are considered on the retreating side (RS). In advancing side, the material flow remains consistent with weld direction. Plastic deformation allows the atomic displacements for creating metallic bonds within the weld zone. The microstructure at weld zones therefore depends on the recrystallization. Tensile test, flexural test, hardness, and impact test are conducted on the welded joints. Tensile and flexural tests are conducted on universal testing machine (UTM). Hardness test is conducted on Brinnel’s hardness testing machine and impact test is conducted on Chapy impact testing machine (300J).

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Pin

shoulder

Fig. 3.1 Friction stir welding tools of different pin depths.

Tool rotation Weld speed Clamps

RS AS Work-2 Work-1 Base plate Work table

(A)

(B) Fig. 3.2 Workpieces in fixtures before welding. (A) Schematic of FSW (1: Advancing side, 2: Retreating side). (B) Experimental setup.

3.2.1 Tensile test Tensile tests were performed 3 times for each welding parameter at room temperature on a 100 ton Instran UTM machine at a rate of 2 mm/min ram speed. The hydraulic-operated ram with computerized recording

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facility provides the stress-strain diagram of each sample till it breaks. During the tensile test, the elongation was recorded with an extensometer with a gauge length of 45 mm. The tensile testing samples are of 100 mm gauge length, 20 mm wide with 25 mm fillet radius and 5 mm thick. These are cut from the transverse direction of the weld. Using three point tests, the bending deflection is measured.

3.2.2 Flexural test Bending test is used to measure the flexural modulus and strength. This test is performed on UTM with either 3 point or 4 point bending fixture. The elongation recorded is an indirect measure of strength and modulus.

3.2.3 Impact test Using Charpy testing machine (300 J maximum impact energy of pendulum), the specially prepared weld samples are tested. The energy absorbed in fracturing a test piece at high velocity is predicted. The impact resistance of a part is, in many applications, a critical measure of service life. Many materials are capable of either ductile or brittle failure, depending upon the type of test and rate and temperature conditions. They possess a ductile/brittle transition that actually shifts according to these variables.

3.3 Theoretical considerations of energy supplied As the process begins, tool heat transfer is considered as steady, whereas, in the workpieces, the generated heat input along the joint line changes as a function of time and position. The energy balance can be described by [18]. Qin ¼ Q + Qloss + Qc

(3.1)

where Qin is heat source flux generated by interaction of tool and work, Q is holding heat in welded region, Qloss is heat lost from workpieces through base plate, Qc is the heat lost from the remaining surfaces to surrounding air through convention. Thus, production and distribution of heat on the workpieces is the main focus. Heat produced Qin is influenced by the contact conditions of workpiece and tool interface. Obviously, it is sum of heat created by (i) workpiece-tool pin side interfaces Q1, (ii) tool shoulderworkpiece contact region Q2, and (iii) workpiece and tool-pin bottom

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Fig. 3.3 Three different sources of heat input.

interfaces Q3. Fig. 3.3 shows the regions of different heat generations along with four zones of weld [19]. These heat inputs are, respectively, given in terms of radius of shoulder (Rs), radius of pin (Rp), pin length (hp), and friction coefficient (μ) between the interfaces and applied axial pressure (P) as [20]: 2π ð Rðp

Q1 ¼

μPωr 2 drdθ ¼ 0 0 2ðπ R ðs

Q2 ¼

μPωr 2 drdθ ¼

2πμωPR3p 3   2πμωP Rs3  Rp3 3

(3.2)

(3.3)

0 Rp 2π ð hðp

Q3 ¼

μPωRp2 dzdθ ¼ 2πμωPR2p hp

(3.4)

0 0

Here, ω is tool rotational speed in radians per second. The resulting energy input E is obtained by dividing the total heat supplied Qin by welding speed u. As the applied pressure P is constant, unit input power is computed as E ¼ 60Qin/(u  P).

3.4 Results and discussion Three levels of each of weld speed and tool rotation along with four different tools of varying pin lengths (2.2 mm, 2.8 mm, 3.2 mm, and 3.5 mm) are considered. Controlled force friction stir welding is conducted on vertical milling machine with proper fixtures and back plate setup. Twenty sets of isogeometric samples, each of AA5251 and AA6063, are used. Feed rates (weld speeds) are selected from the possible combinations on the milling (as 18, 22, 25, 37 mm/min) along with three tool rotations

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(A)

(B)

(C)

Fig. 3.4 Mechanical characterization samples. (A) Tensile specimens. (B) Notch impact sample. (C) Bending sample as per ASTM standard.

(760, 1130, 1340 rpm). The tools are varied one after the other and a total 20 number of experiments are reported. After welding is completed, the jointed member is removed from fixture and specimens for tensile, impact, flexural, and microstructure are cut in lateral direction. Fig. 3.4 shows some of the specimens prepared after welding. First the tensile testing is performed. Fig. 3.5 shows the measured stress-strain diagrams for two of the sample test cases. The variations of ultimate tensile strength (UTS) as a function of weld speed for four tools with different pin lengths are shown in Fig. 3.6 for three tool rotations. For tool with 2.2 mm pin length, it is observed that the tensile strength is increasing with increase in weld speed for tool rotation 760 rpm, while it is decreasing with weld speed at high tool rotations. For higher tool lengths, it is seen that the tensile strength is reducing with increase in feed rate at 1130 rpm; however, it is not much affected at 1340 rpm. Thus, when high tool rotations are used, it is recommended to adopt lower weld speeds for achieving good tensile strength of weld. As maximum tensile strength is observed with 3.5 mm tool, the results of flexural elongation of these samples at two different tool rotations are shown in Fig. 3.7. It is seen that the elongation is rapidly reducing for 1130 rpm tool rotation. Impact test samples are prepared based on European EN 10045 standard. Samples with V-notch of 45 degree, 2 mm depth with a 0.25 mm radius of curvature at the base of notch are prepared. Energy absorbed (impact toughness) by samples with impact is a measure of impact strength. Fig. 3.8 shows the variation of impact toughness with weld speed at different tool rotations for two types of tools. It is observed that at lower pin length conditions, impact toughness increases for smaller values of tool rotation. On the other hand, at higher pin length condition, the weld samples have an increasing trend of impact toughness with larger tool rotation.

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50

Tensile stress (MPa)

40 30 20 10 0 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 Tensile strain (%) 70 Tensile stress (MPa)

60 50 40 30 20 10 0 0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

Tensile strain (%)

Fig. 3.5 Stress-strain diagrams for first two specimens.

Table 3.3 shows the 20 sets of experiments taken up along with recorded data of ultimate tensile strength, flexural elongations, impact toughness values, and theoretical unit input power supplied. As it is seen with bold numbers, the energy levels in the last column are relatively small for tool rotation of 760 rpm with the tool having the lowest pin length. However, as the pin length increases to 3.5 mm, the lower energy level is seen at a speed of 1130 rpm. With the decrease in energy consumption, the designer should also check for the other constraints like, smaller length of heat-affected zone, the limitation of maximum temperatures well below the melting points of base metals, etc. The weld speed, tool rotation, shoulder and pin radii, etc. can be taken as the design variables to further minimize the energy consumption from the system. The collected 20 point data may be used to train a neural network system so as to generalize the interpolation function, so that it can generate energy at any intermediate

tool with pin length=2.2 mm

70

70

tool rotation=760 rpm tool rotation=1130 rpm

50

tool rotation=1340 rpm

40 30 20

UTS (MPa)

UTS (MPa)

60

18

22

25

tool rotation=1340 rpm

40 30

0

37

18

weld speed m/min

(A)

(B)

tool with pin length=3.2 mm

40 30

37

tool rotaon=760 rpm

80

tool rotaon=1130 rpm

70

tool rotaon=1340 rpm

60 UTS (MPa)

50

22 25 weld speed m/min

tool with pin length=3.5 mm

tool rotaon=760 rpm

60 UTS (MPa)

tool rotation=1130 rpm

50

10

0

tool rotaon=1130 rpm tool rotaon=1340 rpm

50 40 30

20

20

10

10 0

0 18

(C)

tool rotation=760 rpm

60

20

10

70

tool with pin length=2.8 mm

22 25 weld speed m/min

18

37

(D)

22 25 weld speed m/min

Fig. 3.6 Effect of weld speed on the ultimate tensile strength. (A) tool-1. (B) tool-2. (C) tool-3. (D) tool-4.

37

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flexural test with tool of 3.5 mm pin length 20 bending elongaon in mm

1130 rpm 1340 rpm

18 16 14 12 10 15

20

25

30

35

40

work speed in mm/min

Fig. 3.7 Flexural elongation of weld samples.

760 rpm (2.2mm pin length) 1340 rpm(2.2 mm pin length) 1130 rpm (3.5 mm pin length) 1340 rpm (3.5 mm pin length)

impact toughness (J)

25

20

15

10 15

20

25 30 weld speed mm/min

Fig. 3.8 Impact toughness of samples with two different tools.

35

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Table 3.3 Combination of welding parameters used in experiments. Weld Ultimate Pin speed tensile Flexural Impact Unit input S. length Rotation (mm/ strength deflection toughness energy × 103 (mm2) No (mm) (rpm) min) (MPa) (mm) (joules)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

2.2 2.2 2.2 2.2 2.2 2.8 2.8 2.8 2.8 2.8 3.2 3.2 3.2 3.2 3.2 3.5 3.5 3.5 3.5 3.5

760 760 1130 1340 1340 760 1130 1130 1340 1340 760 760 1130 1130 1340 760 1130 1130 1340 1340

22 37 25 18 22 25 22 37 18 25 18 22 37 25 37 22 37 25 18 37

49.15 61.42 44.36 38.75 36.00 27.56 58.69 61.56 65.03 57.44 53.53 59.13 41.67 56.84 53 48.8 61.01 67.14 53.49 44.19

17.4 16 21.8 17.8 16.5 17.2 17.4 19.2 16.4 17.2 18.4 16.6 19.2 14.2 19.2 12.2 10.2 18.2 19.1 17.23

16 22 28 16 12 16 18 38 32 40 52 28 60 32 48 20 12 20 16 20

15.8981491 9.4529535 20.8014729 34.2600464 28.030947 14.5250351 24.5414019 14.5921849 35.5693475 25.6099302 20.6687189 16.91077 14.9502754 22.1264075 17.7286451 17.2145563 15.2188432 22.5238879 37.0968655 18.0471238

values of rotation, weld speed, pin length, etc. Ultimately, this function can be employed as a subroutine in optimum design of the friction stir welding process with dissimilar aluminum alloy plates. After completing all the experimental part, the next step is to go for micro- and macrostructure analysis. Another set of 20 samples is prepared for understanding the microstructure in the weld region using scanning electron microscopy. In order to examine the fracture process in more detailed manner, SEM micrographs of the fractured surfaces on the failed specimen are observed. The ductile fracture is associated with most of the samples where the nucleation of voids occur due to plastic flow.

3.5 Conclusions This chapter presented the test cases of sustainable manufacturing with friction stir welding of dissimilar aluminum alloy welds. Thin AA5251 and

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AA6063 plates, each of 5 mm, were welded with four specially prepared stainless steel weld tools. Weld speed and tool rotation were varied and different weld samples were formulated. The mechanical properties such as ultimate tensile strength, impact toughness, and flexural elongation were measured for each case. In addition, using theoretical formulation, the input energy supplied to the process was also estimated. It was observed that the tool rotation has drastic effect compared to the weld speeds. At high tool rotations, lower weld speeds would result in better stress distribution, good microstructure, and other mechanical and thermal properties.

References [1] S. Vijay, S. Rajanarayanan, G.N. Ganeshan, Analysis on mechanical properties of gas tungsten arc welded dissimilar aluminum alloy (Al2024 & Al6063), Mater. Today Proc. 21 (Part 1) (2020) 384–391. [2] Y. Wang, W. Tao, S. Yang, A method for improving joint strength of resistance spot welds of AA5182-O aluminum alloy, J. Manuf. Process. 45 (2019) 661–669. [3] W.M. Thomas, E.D. Nicholas, J.C. Needham, M.G. Murch, P. Temple-Smith, C.J. Dawes, Friction-stir butt welding, GB Patent No. 9125978. 8, International patent application No. PCT/GB92/02203, 1991. [4] R.S. Mishra, Z.Y. Ma, Friction stir welding and processing, Mater. Sci. Eng. A 50 (2005) 1–78. [5] G. Cam, G. Ipekoglu, Recent developments in joining of aluminum alloys, Int. J. Adv. Manuf. Technol. 91 (2017) 1851–1866. [6] E.G. Cole, A. Fehrenbacher, N.A. Duffie, M.R. Zim, F.E. Piefferkom, N.J. Ferrier, Weld temperature effects during friction stir welding of dissimilar aluminum alloys 6061T6 and 7075T6, Int. J. Adv. Manuf. Technol. 71 (2014) 643–652. [7] H.J. Zhang, M. Wang, Z. Zhu, X. Zhang, T. Wu, Z.Q. Wu, Impact of shoulder concavity on the tool-tilt friction stir welding of 5052 aluminum alloy, Int. J. Adv. Manuf. Technol. 96 (2018) 1497–1506. [8] J.C.V. Juarez, G.M.D. Almaraz, R.G. Hernandez, J.J.V. Lopezm, Effect of modified pin profile and process parameters on friction stir welding of aluminum alloy 6061T6, Adv. Mater. Sci. Eng 2016 (2016), https://doi.org/10.1155/2016/4567940. [9] N.M. Daniolos, D.I. Pantelis, Microstructural and mechanical properties of dissimilar friction stir welds between AA6082-T6 and AA7075-T651, Int. J. Adv. Manuf. Technol. 88 (2017) 2497–2505. [10] W. Safeen, S. Hussain, A. Wasim, M. Jahanzaib, H. Aziz, H. Abdalla, Predicting the tensile strength, impact toughness and hardness of friction stir welded AA6061-T6 using response surface methodology, Int. J. Adv. Manuf. Technol. 87 (2016) 1765–1781. [11] J. Tang, Y. Shen, Numerical simulation and experimental investigation of friction stir lap welding between aluminum alloys AA2024 and AA7075, J. Alloys Compd. 666 (2016) 493–500. [12] X. Liu, S. Zhao, K. Chen, J. Ni, Material flow visualization of dissimilar friction stir welding process using nano-computer tomography, J. Manuf. Sci. Eng. 140 (2018) 111010–111011. [13] M.M. AbdElnabi, A.B. Elshalakany, M.M. Abdel-Mottaleb, T.A. Osman, A. ElMakadem, Influence of friction stir welding parameters on metallurgical and mechanical properties of dissimilar AA5454-AA7075 aluminum alloys, J. Mater. Res. Technol. 8 (2019) 1684–1693.

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[14] M. Bevilacqua, F.E. Ciarapica, A. D’Orgzio, A. Forcellese, M. Simoncini, Sustainability analysis of friction stir welding of AA5754 sheets, Proc. CIRP 62 (2017) 529–534. [15] S. Azeez, M. Mashinini, E. Akinlabi, Sustainability of friction stir welded AA6082 plates through post-weld solution heat treatment, Proc. Manuf. 33 (2019) 27–34. [16] S. Azeez, M. Mshinini, E. Akinlabi, Road map to sustainability of friction stir welded Al-Si-Mg joints using bivariate weibull analysis, Proc. Manuf. 33 (2019) 35–42. [17] P.L. Threadgill, A.J. Leonard, H.R. Shercliff, P.J. Withers, Friction stir welding of aluminum alloys, Int. Mater. Rev. 54 (2) (2009). [18] M. Boukraa, N. Lebaal, A. Mataoui, A. Settar, M. Aissani, N. Tala-Ighil, Friction stir welding process improvement through coupling an optimization procedure and threedimensional transient heat transfer numerical analysis, J. Manuf. Process. 34 (2018) 566– 578. [19] R. Nandan, T. DebRoy, H.K.D.H. Bhadeshia, Recent advances in friction-stir welding – process, weldment structure and properties, Prog. Mater. Sci. 53 (6) (2008) 980–1023. [20] H. Schmidt, J. Hattel, Thermal modelling of friction stir welding, Scr. Mater. 58 (2008) 332–337.

CHAPTER FOUR

Heat pipe-embedded tooling for sustainable manufacturing I. Kantharaj, S.J. Vijay, X. Ajay Vasanth, S. Mohanasundaram, and Rajakumar S. Rai Department of Mechanical Engineering, Karunya Institute of Technology and Sciences, Coimbatore, Tamil Nadu, India

4.1 Introduction Green or sustainable manufacturing mainly deals with the establishment of a manufacturing process that reduces pollution and industrial waste. Such environmentally friendly machining has become mandatory for both industrial and social development. When applied to green machining, the minimization or elimination of cutting fluid is primarily focused. Cutting fluids are commonly flooded at the cutting zone during machining. To minimize friction, cutting fluids were applied and it reduced the temperature at the interface of the cutting tip and the workpiece. The chips produced in the cutting zone are removed additionally. This cutting fluid removes the heat generated from the primary cutting area during machining, resulting in prolonged tool life when it is used effectively. There are several undesirable aspects that are present when cutting fluid is used during machining. Studies found that using metal cutting fluid during machining is responsible for health and environmental hazards. The usage of cutting fluids can cause ailments such as skin issues, respiratory irritation, asthma, skin cancer, etc. The cutting fluid disposal is a severe threat to the environment as it pollutes soil and groundwater. It is essential to treat waste cutting fluid properly before disposing, which often proves to be expensive. These issues associated with cutting fluids call for an alternative technique that minimizes or eliminates cutting fluids during metal removal. This chapter not only reviews the research literature associated with metal cutting-related issues, but also suggests eco-friendly and sustainable solutions that can be implemented in all industries without much of modification in the machine tools. The chapter provides a better understanding

Sustainable Manufacturing and Design https://doi.org/10.1016/B978-0-12-822124-2.00004-4

© 2021 Elsevier Ltd. All rights reserved.

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of the issues faced during machining and discusses the contemporary research findings in the area of green machining.

4.2 Metal cutting practices The cutting process where the unwanted material is removed from the surface of workpiece by chips is referred as metal machining. Machining includes milling, drilling, boring, and turning conducted with a single or multipoint cutting tool where the unwanted material is removed from the workpiece to obtain the required geometry [1]. Cutting fluids aid the machining process by means of cooling and lubrication. Cutting fluids can be applied by the following categories: • Dry machining: The process where machining is performed without cutting fluid. • Wet machining: The process where the cutting fluid is supplied in surplus quantities and it guarantees minimum friction and low temperature between the tool-work interface. • Minimum quantity lubrication: The process where machining is performed by applying coolant in mist form, or in other words, coolant is applied in a very minimal quantity at the cutting zone with certain amount of pressure. It is also referred as near-dry machining. • Heat pipe-assisted machining: The process where machining is performed with a heat pipe which is a passive heat transfer device that enables machining to be performed even in a dry manner. • Cryogenic cooling: It is commonly known as low thermal physics where the cutting operation is performed with very low temperature ( 150°C to 273°C) at the tool-work interface. While carrying out turning operation, Adler et al. [2] observed the enormous heat escalation because of the friction at tool-work interface and it triggered problems concerning surface quality and tool life. According to them, the contact between the tool and workpiece caused a huge amount of friction and heat. This resulted in accelerated tool wear which led to the breakage of the cutting edge of tool. It was also mentioned that the tool damage became inevitable due to thermal stresses developed during machining. Subsequently, surface roughness of the workpiece and machining precision were in direct relation to the cutting temperature. Davim et al. [3] cited that these issues were traditionally solved by applying coolants and lubricants. Cutting fluids were helpful for increasing tool life and improving the surface finish of the work. Applying cutting fluids

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during machining affected cutting temperature, removal of chips from the cutting zone, and erosion of the workpiece. Sharma et al. [4] investigated the use of engine oil as cutting fluids during metal cutting. They have mentioned that even though the characterizations of the cutting fluids can be designated from the above-mentioned applications, the sole purpose of a cutting fluid was to bring about cooling and lubrication. Sharma et al. [4] concluded that the effectiveness of cutting processes can be increased by implementing several new technologies to regulate the cutting zone temperature. A few other technologies include flood cooling, cryogenic cooling, solid lubrication, minimal quantity lubrication (MQL), and use of high-pressure coolants. In metal cutting research, vast research work is carried out specifically on MQL and cryo-methods. Most of these concentrate on optimizing the process parameters to achieve desired cutting temperatures, thereby improving the quality of the machined product. Though MQL consumes a minimum amount of lubricating fluid, they are found to be expensive and difficult to recycle. One of the disadvantages mentioned by various researchers is the failure of dissemination of cutting fluid between tool-work interfaces. This results in an ineffective heat removal process. Fig. 4.1 shows the various cutting fluid application methods such as flood cooling, cryogenic cooling, minimum quantity lubrication (MQL), solid lubricants, compressed air/gas coolants, etc. Jayal et al. [5] mentioned that the usage of cutting fluids had some hostile effects such as operator’s dermatitis, environmental effluence during machining, etc. Water pollution and soil contamination are a major threat that is present during discarding of waste cutting fluid. Shashidhara and Jayaram [6] mentioned in his research that green manufacturing is economically and environmentally beneficial. Lawal et al. [7] stated that the inevitability of green manufacturing can be justified owing to several factors such as work-related diseases among the machine operators, government policies with respect to the environmental issues, and overall cost lessening needed in manufacturing industries. Siller et al. [8] discussed that the green machining is considered to be one of the techniques that concentrate on minimizing or eradicating the usage of coolant during machining operations. According to him, green machining techniques were classified on the basis of processing, cooling, and lubrication of the cutting fluid. Chetan et al. [9] illustrated numerous properties of sustainable machining techniques as shown in Fig. 4.2. Green/Sustainable/Clean manufacturing

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Fig. 4.1 Cutting fluid application methods.

can be defined as a method of machining that consumes less energy, reduces wastage, and minimizes the impact on the environment. From the articles cited above, it is imperative to know that dry machining is highly desirable and essential for new manufacturing initiatives of the future. Because of its cost-cutting profile in machining and the absence of environmental issues, it will be considered as one of the major alternate methods adhering to international safety regulations for manufacturing industries.

4.3 Dry machining To eliminate the negative effects of cutting fluid, machining performed in the absence of cutting fluid is labeled as dry machining. Dry Machining is becoming very popular in modern manufacturing industries. Sreejith and Ngoi [10] stated that attaining green machining processes is feasible by eliminating the usage of cutting fluids. It also suggested that dry

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Fig. 4.2 Characteristics of sustainable machining.

machining will be the most efficient way for greener manufacturing if it overcomes the problem of poor heat dissipation. They also suggested that further research on the incorporation of heat-removing mechanisms without causing pollution to the environment is necessary. Hence, many researchers have envisaged in an efficient process to remove cutting heat. Vamsi Krishna and Nageswara Rao [11] observed that the expenses related with the usage of cutting fluids were more than the manufacturing cost. To minimize the concerns related to the environmental problems and machining issues, implementation of dry machining was considered as an alternative. Weinert et al. [12] explained the properties such as hardness, sharpness, better rake and clearance angles, etc., which are essential for tool materials employed in dry machining processes. Fig. 4.3 demonstrates that the dry machining can aid in developing an eco-friendly machining process, decrease in cutting fluid cost, and provide job satisfaction among the metalworking operators. Klocke and Eisenblatter [13] mentioned that dry machining during metal cutting processes has some downsides such as the nonexistence of cutting fluid which increases the temperature and friction at the tool-work interface. During dry machining, as workpiece material gets heated up, it evades its dimensional accuracy and surface reliability and further its metallurgical properties were also significantly altered. Arulraj et al. [14]

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Fig. 4.3 Benefits of implementing dry machining.

found that in the existing metal cutting environment, dry cutting is very hard to be implemented as it requires an extremely rigid machine and cutting tools with high hot hardness and relevant properties. Due to the hardness of some materials like Titanium, the heat escalation and reduction in tool life may occur. During those issues, extremely rigid machining tools are required. Bhemuni et al. [15] proposed that dry cutting is suitable for traditional machining of workpieces such as steels, cast irons, and steel alloys. It was also further stated that dry cutting is not suitable for aluminum alloys. During dry cutting, high friction is produced between the tool and workpiece, which in turn increases the temperature and causes abrasion, oxidation, and diffusion. Rotella et al. [16] stated that the adhesion of tool and chip affected tool life and had a negative impact on the surface quality of the workpiece such as build-up edges. The temperature was also found to be higher during such adhesions. Chetan et al. [9] found that strong adhesion of metal particles is the major concern of dry cutting. They proposed that for a certain combination of tool and workpiece material, metal particles from chip get attached to the tool rake face, thereby reducing the surface quality of machined parts.

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Liang et al. [17] proposed that the degree of tool wear was higher at elevated temperature during dry cutting. It was also stated that the tool atoms materially drawn out from the tool were moved away along with unwanted metals during machining. Das et al. [18] stated that a higher amount of chemical commotion between tool and chip can be found at an augmented temperature which later exaggerated the tool crater wear. Debnath et al. [19] stated abrasion as the main cause of tool wear and at higher temperatures tool wear due to abrasion became intense. Gupta and Laubscher [20] mentioned that it was difficult to achieve the required geometrical precisions of the final product due to momentous heat retention during machining. Sharma and Sidhu [21] found that the remembered heat caused thermal distortions in machined parts during dry machining. It is obvious that dry machining can develop major geometrical errors when the component cools down after the cutting process. It was also stated that at different machining conditions, the temperature at the cutting zone increased, leading to an expansion in the material. Zhang et al. [22] found that there was a loss of geometrical form and accuracy in the machined parts after cooling down. It was observed that there was severe localized deformation during machining. Shokrani et al. [23] conveyed that a worn-out tool reduced the surface quality of finished products and also affected Material Removal Rate (MRR). Owing to such difficulties in machining, materials that are difficult to machine rely mostly on cutting fluids as a substitute to dry machining techniques. Bordin et al. [24] had substantial difficulties while machining steels and also austenitic stainless steel, nickel, and titanium alloys without cutting fluids. Wagner et al. [25] observed difficulty in machining Ti-5553 austenitic stainless steel because of higher strength and fracture toughness during coolant-less cutting. In dry machining, low thermal conductivity coupled with elevated heat generation results in poor heat dissipation. It was observed that the premature tool failure was caused by the elevated tool temperature which was produced during the metal cutting processes. Based on the review of literatures, the issues with dry machining can be summarized as, higher temperatures at the critical cutting zone result in poor surface finish of, higher cutting force, higher tool wear, and defective finished components. In addition to this, machining of harder materials resulted in metallurgical modification in the workpiece as well as severe tool wear. With all those hostile effects of dry machining, green manufacturing techniques were principally desired in the metal cutting industries.

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4.4 Minimum quantity lubrication (MQL) While substantiating dry machining process, the alternate solution for overcoming various disadvantages present in dry as well as wet machining is usage of a very minimum amount of cutting fluids which is commonly referred as Minimum Quantity Lubrication (MQL) technique. Weinert et al. [12] observed that human health as well as environment was pretentious badly by the usage of large amount of cutting fluids, during its use and disposal. They concluded that the avoidance of excessive use of cutting fluids ensured better health in human beings and assisted the green environment. It was demonstrated through their work that the costs related to waste disposal elevated; the industries were strained to enforce strict policies and technologies to minimize the usage of coolants. Thepsonthi et al. [26] mentioned that dry machining could be the next technology for substituting wet machining technique. But seldom did they report the disadvantages of dry machining. Hence, a suitable alternative has to be considered which falls in between the dry and wet machining techniques. And various ecologically conscious machining techniques in metal cutting operations such as dry cutting, MQL, and gas-based coolants were illustrated by Shokrani et al. [23]. Those specified techniques eliminated the usage of conventional cutting fluids during machining. Elimination of heat from the cutting zone during machining is the primary objective. Researchers have been developing technologies to substitute conventional cooling methods. Brockhoff and Walter [27] suggested an intermediate cooling technique which was present between dry and conventional wet turning processes. They believed that their proposed procedure can overcome environmental and machining issues. Wertheim et al. [28] explained about a new coolant applying technique almost resembling dry turning process. In this method, a very minimum measure of cutting fluid is applied to the cutting zone. Tools were specially designed to ensure that the cutting fluids were targeted at the tool-chip interface. They stated that this technique resulted in achieving better cutting performance with enhanced tool life. Diniz and Micaroni [29] explained that MQL technique was expected to minimalize or eradicate the usage of cutting fluids used while machining. It is assumed that the technique is the effective solution for a sustainable environment in machining by eliminating major amount of coolant used. They also mentioned that, with increased depth of cut, it became difficult for implementation and it also shortened tool life.

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Mazurkiewicz et al. [30] observed a low cutting force, improved chip formation, and enhanced surface finish while they applied MQL. Chepe and Philip [31] achieved cleaner production and minimized the usage of coolant drastically up to 5 mL per minute. Braga et al. [32] concluded that the MQL/NDM techniques may be adopted where dry machining is neither possible nor economical. Varadharajan et al. [33] engineered a device for applying a lesser amount of coolant of high quality at the cutting zone in the form of aerosol. Varadarajan et al. [34] implemented a nozzle to directly apply the aerosol to the primary cutting zone. It was sprayed at high pressure with the help of the nozzle, instead of using traditional flood coolants. The device consisted of a discharge nozzle, cutting fluid sump, and atomizer to carry out the operation. Sharma and Sidhu [21] established an empirical standard to relate the friction present between the tool and workpiece using cutting speed and tool feed rate during MQL-based machining. Rahman et al. [35] proposed that the MQL practice exhibited better performance when equated to that of wet machining. This statement held true even when machining was performed at higher cutting speeds and higher feed rates. Based on the results, it was summarized that MQL helped in diminishing the friction between the tool-work interface. Attanasio et al. [36] employed two techniques, internal feed and external feed Minimum Quantity Lubrication (MQL) systems for experimentation. It was found that compared to the external feed system, the internal feed system was more beneficial. They reported that the mixture setting was easy to control due to the mist, thereby reducing the hazardous vapors while machining. Weingaernter et al. [37] suggested that MQL could be a practical substitute, which will depend on the cutting conditions, machining parameters, and types of cutting fluids. Sharma and Sidhu [21] in their study about coolant and lubrication, suggested that MQL may serve as a better cooling option. It was noted that MQL eliminated the requirement of additional processes for the recycling of chips. Aoyama et al. [38] mentioned that the mechanism of MQL worked more as a lubricant than as a coolant. Major quantity of heat from the cutting zone was removed because of the excellent lubricity of a good MQL system. The removal of the heat during cutting from the cutting tool reduced its tool wear. Kamata and Obikawa [39] experimented with the high-speed turning of Inconel-718 with different coated tools and compared tool life and surface

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roughness under dry, wet, and MQL techniques. It was proposed that the quality of machined parts considerably enhanced when MQL was implemented. A comparison with other machining techniques exposes MQL to be far more superior than both wet and dry machining. MQL has become the most preferred coolant applying technique for turning process as it allows an easy and a flexible way of altering both the nozzle position and orientation. Tawakoli et al. [40] found that machining performances improved when the MQL technique was used for the turning operation. Shokoohi et al. [41] investigated the applicability of an innovative combined cooling method (CCM), where the workpiece is precooled. This was achieved by initially cooling the workpiece with cooling liquids and subsequently using cutting fluid through the MQL technique. It was observed that this procedure had a positive impact on health and ecological-related issues. Zhang et al. [22] experimented on milling operation and proposed that MQL based cooling method has improved the cutting performance during machining of steels. It also helped in easier machining of difficult-to-cut alloys. Chilled air has a higher capacity to remove heat from cutting zone than air at room temperature. Sharma et al. [42] conveyed that MQL also minimized the environmental impact as lower quantity of fluid is used and thus discharging them is not needed at all. But chilled air was never readily available, thus adding additional cost to the production processes. It was also mentioned that using the right lubricant was very important in MQL applications. Banerjee and Sharma [43] stated that the perfect metal cutting fluid adhered to the surface of the tool. This in turn created a barrier between the cutting tool and the workpiece. This technique was termed as “Minimal Quantity Lubrication,” “Near-Dry Machining” (NDM), “Micro-Lubrication,” or “Micro-Dosing” and sometimes even got incorrectly referred to as “mist coolant.” Barczak and Batako [44] inferred that MQL has numerous advantages over other conventional methods of applying cutting fluids and MQL is very effective in removing the cutting temperature from the primary cutting zone. Also, MQL was mostly introduced in the form of a mist, which when inhaled by the operator can be carcinogenic and causes eye irritations and they don’t remove the chips from the cutting zone. This was observed during certain operations like boring. Zhang et al. [45] illustrated that it also cannot provide coolant to the tool-chip interface after the tool had penetrated inside the workpiece, which was also reported in the literature pertaining to boring with MQL. The nozzle also might get damaged/clogged due to the chip

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flow. These were some of the demerits of MQL and other cooling methods. Thus, there is a need for an improved and reliable method for removing the heat from the cutting zone.

4.5 Heat pipe-embedded cutting tools Thermal conductivity and phase transition are combined to form a heat pipe that has the capacity of transferring the heat in an effective manner. Zhao et al. [46] listed out its applications in space crafts, computer systems, and in other systems that involve high power consumption and generate a lot of heat. Thus, many researchers attempted to employ heat pipe during metal removal as a mechanism to remove the heat produced in the cutting zone without application of any form of coolant. Fig. 4.4 illustrated the schematic view of the heat pipe; an effective alternative was to replace other traditional methods of eradicating heat from a tooltip. Ding and Hong [47] in his investigation about chip breaking during machining of AISI 1008, explained the working of a heat pipe. Heat pipe has three zones, an evaporator zone, an adiabatic zone, and a condenser zone. The heat from the external source is absorbed by the evaporator and converts working fluid to vapors. The vapor is then forced to the condenser through the adiabatic zone by the created vapor pressure. In the condenser zone, the vapor loses its latent heat of vaporization to environment and it condenses. After this, it is driven back to the evaporator zone by the capillary action produced by the meniscus in the wick structure. Thus, the heat

Fig. 4.4 Schematic structure of a heat pipe.

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absorption takes place and it continues till the existence of capillary pressure. Employing heat pipe during machining of metals will be the best alternative for traditional cooling methods. Zhu et al. [48] stated there were zero requirements of cutting fluids while using heat pipe during machining to eliminate the temperature produced in the primary cutting zone. Ding and Hong [47] mentioned coolants are totally hazardous to the environment as well as to the machine operators. Thus, the heat pipe technology is much preferred over other methods for eco-friendly machining because of their coolant-less machining. Chiou et al. [49] in their investigations about the heat pipe-embedded turning tool (Fig. 4.5), mentioned about the positive effect in the workpiece material. It was found that under dry cutting conditions, the chips were blue in color showing that they were oxidized due to elevated temperature. The color of the chip produced was dark brown in the case of heat pipe machining, which was an indication of lower temperature. It had no effect on the metallurgical properties of the material. Zhu et al. [48] in his experiments on milling process with heat pipe-assisted tools, noticed a reduced cutting temperature, increased tool life (1.4 times), and better surface finish compared with the dry milling process. Hung et al. [50] noted that the development of the build-up edge drastically reduced compared with dry machining and traditional cooling method since most of the heat was removed continuously. It was further stated that when heat pipe was embedded in an end-mill, there was an enhanced machining index. Jen et al. [51] investigated heat pipe-embedded drill through a hole that was made for the heat pipe with the required tolerance. Results stated that thermal management was good in heat pipe machining in comparison with the dry and traditional methods. Lin et al. [52] compared the heat pipe-assisted tool as represented in Fig. 4.6 with dry machining. It was stated that heat dissipation of heat pipe showed a better result when compared to dry drilling. There was no

Fig. 4.5 Schematic view of heat pipe-embedded turning tool.

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Fig. 4.6 Schematic view of heat pipe-embedded drilling tool.

adhesion of workpiece material on tool, thus leading to decreased chances for producing BUE. Experiments with heat pipe showed an increased tool life of 1.6 to 2.2 times, compared to that during dry conditions. Robinson Gnanadurai and Varadarajan [53] in his investigation with the minimal fluid application during turning of hardened AISI 4340, employed heat pipe as an auxiliary heat removal mechanism. Jen et al. [51] stated that heat pipes can be introduced in the machining process to eliminate heat and increase the machinability properties. He also credited heat pipes for their ability to eliminate heat without cutting fluid, thus providing a cleaner zone for metalworking. Sreejith and Ngoi [10] stated the limitations of using heat pipe during machining. Heat pipes cannot reach the tool’s tip because the diameter of the heat pipe affects the maximum stress levels than the cutting temperature produced.

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During heat pipe-assisted drilling, Kantharaj et al. [54] found that the cutting temperature reduced up to 33.91% when compared to the dry machining process. It is stated that the machining temperature drop is essential to prolong tool life during metal cutting practices. The tool wear was also minimum and a 50% reduction was witnessed during the process. This reduction in cutting tool wear served as proof for enhancing tool life while heat pipe-embedded tools were used. During drilling, heat pipe-assisted hole-making required less energy compared to dry drilling. This was achieved by the estimated 2% reduction in cutting force. Thus, experimental results carried out by the authors proved that heat pipe-assisted cooling during hole-making operations effectively replaced traditional cooling methods. The authors also [55] experimented with heat pipe-aided tool for boring operation (Fig. 4.7). The tool with heat pipe enhanced heat dissipation at the tooltip showing an average reduction of 25.8% in cutting temperature. This in turn influenced the tool wear and was found to be 66.5% lesser than that of the tools used in conventional boring operation. Since the tool wear reduction is directly related to tool life, it was evident by the reduction that was noticed in the cutting force. Experiments were carried out on milling operation (Fig. 4.8) with the help of heat pipe-assisted multipoint cutting tool. It was witnessed that cutting temperature reduced with multiple heat pipe-assisted milling tool. There was a 35% lessening in cutting temperature in comparison to dry milling operation. This experimentation illustrated the effectiveness of heat dissipation of those multiple heat pipes. The cutting force produced

Fig. 4.7 Experimental setup showing the boring tool embedded with multi-finned heat pipe.

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Fig. 4.8 Experimental setup showing milling cutter embedded with multiple heat pipes.

during the usage of heat pipe-embedded milling tool was considerably low when compared to that of dry milling. Due to the lessening in temperature, tool wear was found to be very minimum. The heat pipe-assisted milling tool also ensured that the product is of high quality which was estimated by the surface roughness values of the workpiece. Based on the literatures and the experimental studies carried out by the authors, it was found that heat pipe-assisted tools are the futuristic technology which ensures sustainability in manufacturing processes. Wise implementation of this heat pipe technology in cutting tools can revolutionize the outlook of all conventional material removal processes for the future.

4.6 Conclusion The chapter stated the problems that are routinely faced by metal cutting operators during the cutting process. The problems associated with the tool are higher temperature and increase in cutting force, which impact the tool wear and tool life. These factors are the cause for poor surface properties of the products. Reducing friction eradicates the problems related to the plastic deformation of the tool and the workpiece. As friction is directly associated with temperature rise, cutting fluids are applied in the tool-work interface area to reduce friction and temperature. This ensures considerable improvement in tool life as well. The conventional approach to decrease the friction and temperature at cutting zones is by applying large amount of cutting fluids. Though it passes through the working zone like a flood, it never was focused on the exact

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zone of cutting. In addition, bulk quantity cutting fluids are hazardous to the environment and the operator’s health. The alternate approach to wet machining is dry machining. Due to heat escalation at the primary cutting zone, most of the dry cutting applications fail to deliver desired surface finish and tool life. The large amount of built-up edge will be produced due to friction and it reduces the quality of the workpiece. MQL is an alternate technique to minimize the temperature generated in the cutting zone. It also reduces the consumption of cutting fluids and is an efficient method to lubricate the tool-work interface. The cutting fluid is focused on the primary cutting zone with the help of the application nozzle to eliminate the heat produced at that location. It also decreases environmental impact by eliminating activities such as coolant filtering processes and disposal. However, in MQL, the sudden application of coolant produces thermal shocks, leading to tool damage and poor surface finish of the workpiece. Thermal shock occurs on the work and tooltip due to sudden quenching. Application of coolant in a large volume also distorts the workpiece and dimensional stability is affected. MQL is considered as a better lubricating technique than flood cooling. But the demerit of the MQL technique limits its effectiveness during machining of difficult-to-cut materials such as nickel-based alloys and titanium. Heat pipe is a potential alternate technique to conventional cooling methods for dissipating the cutting temperature from the tool tip. It is an unconventional dry machining that effectively transfers the cutting zone temperature in the absence of the cutting fluid. The heat pipe enables cutting tool to perform machining operations without the generation of industrial waste. From the annotations of previous researches and based on the experimental studies carried out by the authors themselves, the results showed substantial merits while heat pipe-embedded cutting tools are employed for cooling. This technique directly minimized the cutting temperature, cutting force, and tool wear, while improving the tool life and product quality. Further, the manufacturing process was found to be much cleaner, ecofriendly, and sustainable.

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CHAPTER FIVE

Sustainable manufacturing of plastic packaging material: An innovative approach Ramakrishna Karantha, Yashaswini Karanthb, Vishal Naranjec, and M.V.N. Sankaramd a

Kimoha Entrepreneurs Ltd., Jebel Ali Free Zone, Dubai, United Arab Emirates Department of Materials Science and Engineering, Texas A&M University, College Station, TX, United States c Department of Mechanical Engineering, Amity University, Dubai, United Arab Emirates d Department of Mechanical Engineering, BITS Pilani, Dubai, United Arab Emirates b

5.1 Introduction In recent times, extensive focus has been accorded to sustainability and downsizing to reduce the usage of quantum of plastics in packaging and various engineering applications. During such efforts to downsize, the biggest challenge is to ensure that the adequate mechanical, physical, and functional properties of components for intended end use are not compromised. Packaging technologists and scientists had been working on various possible options to overcome this challenge. Nowadays, nanocomposites are widely used in a multitude of applications for imparting improved barriers; mechanical, thermal, and biodegradable properties [1]. In addition to these, nanocomposites also find application in active and intelligent food packaging [2]. Two of the major categories of primary packaging used in packaging applications for fast moving consumer goods segment (which primarily covers the food segment and personal care items) are the flexible packaging and rigid packaging. Flexible packaging is also known as flexible laminate and is generally a multilayer type of packaging material, produced by a combination of material, by laminating different layers together using relevant processes to deliver improved barrier and functional properties to the composite laminate [3]. Major properties of flexible laminate to achieve protection of product packed are its moisture barrier, gas/oxygen barrier, and ultraviolet (UV) barrier. Flexible packaging is one of the most commonly used and most optimum packaging options on environmental attributes, Sustainable Manufacturing and Design https://doi.org/10.1016/B978-0-12-822124-2.00005-6

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Table 5.1 Sustainability assessment of packaging options [4]. ProductGHG Water toFossil fuel emissions consumption package consumption (kg-CO2 equiv) (I) ratio Format (MJ-equiv)

88,736 4652 Drink flexible pouch Composite 95,250 (+7%) 5967 carton (+28%) PET bottle 140,231 7319 (+58%) (+57%) Aluminum 275,766 27,105 can (+211%) (+483%) Glass bottle 326,690 25,612 (+268%) (+451%)

Pkg landfilled (g)/1000 kg juice

12,108

97:3

27,734

71,685 (+492%) 28,738 (+137%) 91,812 (+658%) 209,809 (+1633%)

96:4

42,126 (+52%) 34,290 (+24%) 25,388 ( 8%) 364,169 (+1213%)

96:4 95:5 65:35

Notes: A normalized product weight (common value divisible by oil package formats) of 1,188,000 fl. oz. of product was used far Fossil Fuel, GHG, and Water Consumption calculations.

when compared with many other forms of packaging options. Table 5.1 shows the comparative assessment of different packaging options for single serve juice packaging. Rigid packaging usually includes tin cans, cardboard boxes, plastic boxes, or glass containers. Three types of rigid packaging generally used in fast moving consumer goods segment are metal packaging, glass packaging, and plastics packaging. Plastics is the most optimum rigid packaging among the competition from metal and glass as seen from the table above, because of clear advantages of energy consumption, emissions, water consumption, and product quantity filled per gram of packaging. Potential cost savings, weight reduction, and reduced damage/breakage are also important reasons for the general trend to move from glass and metal packaging to plastics packaging. Even in comparison with flexible packaging, rigid plastics packaging emerges as a winner on sustainability platform considering the possibility of recycling and actual postconsumer recycling (PCR) rate, which is explained in detail in the following section.

5.1.1 Flexible packaging Thin aluminum foil, in the thickness range of 6 μ to 12 μ, is extensively used in food packaging application, as a barrier film to facilitate extended shelf life by providing light, oxygen, and moisture barrier to the packaged food

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products [5]. Brand identity of the product is achieved through the graphics printed on a thin polymeric or paper layer on the external surface of the laminate. Generally used polymeric substrate is biaxially oriented Poly Propylene film (BOPP) or PolyEthylene Terephthalate film (PET). Base film used for this print layer is usually in the thickness range of 8 μ to 40 μ. It is laminated to the aluminum foil substrate to form a duplex structure. This duplex structure is further laminated to a sealant layer of another polymeric substrate, made up of either Linear Density Poly Ethylene films (LDPE) or Cast Poly Propylene film (CPP) in the thickness range that usually starts from 20 μ and can be as high as 200 μ or even higher. Common composition of multilayer packaging film is shown in Fig. 5.1. Flexible packaging uses the least quantum of material per unit quantity of product packed. It has the least energy consumption and CO2 emission in comparison with alternative options. However, a major issue with the flexible laminates is the challenge encountered in post-usage recyclability because of the dissimilar material used in its construction. It is almost impossible to segregate the laminated composites to its original input materials because of multiple materials like inks and adhesives used in the process. Hence, it is highly unlikely to find the possibility of primary or secondary recycling of flexible laminates post the intended use. Presence of aluminum foil or metallized coating causes further difficulties in recycling. In order to enable and maximize the usage of postconsumer recycled material, stringent recycling norms and restrictions for usage of dissimilar material are

OUTER (PRINTED LAYER) ADHESIVE BARRIER LAYER ADHESIVE INNER (SEALENT) LAYER

Fig. 5.1 Common composition of multilayer packaging film.

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being enforced in many countries. Plastic Waste Management Rules 2016 released by the Indian Ministry of Environment, Forest, and Climate Change stipulate that recycling of plastic waste generated from the process and at the end of life cycle of packaging shall confirm to Indian Standard IS 14534:1998 (Guidelines for recycling of plastics). Zimbabwe has introduced legislation to outlaw single-use plastics and takeout containers made out of Expanded Poly Styrene (EPS). European Union has voted for single-use plastics directive that will ban plastics products for which alternatives exist on the market, such as single-use plastic cutlery, plates, and items made of oxo-degradable plastics, by the year 2021. Various other countries like Canada, Australia, Tunisia, Peru, UK, Kenya, Taiwan, etc. have announced their own guidelines and efforts to reduce the usage of plastics and promote recycling. With this backdrop, packaging fraternity has been working hard to find a solution to promote recyclability and sustainability of plastics packaging. Overriding compulsion is to avoid the presence of dissimilar material in the packaging to enable primary and secondary recycling postconsumer use, and thus, achieve the overreaching vision of the new plastics economy where plastics never become waste. One of the important layers in the composition of barrier packaging material is the aluminum or metallized layer that provides the required barrier property for the packaging to protect the material packed from the adverse effects of moisture, gas, and UV rays. Packaging technologists and researchers had been striving to find a suitable solution that avoids usage of such dissimilar material in plastics packaging, by designing recyclable structures that provide similar barrier properties. Furthermore, an average consumer always prefers to see the product before making purchase decision. However, its inherent opacity aluminum foil and metalized plastics film used as barrier layer in the flexible laminate prevent the point of sale visibility of the packed product. Hence, it does not promote preferred buying experience at the point of sales. Need of the hour is to provide a suitable alternative to aluminum foil that extends equivalent or better barrier property to the packaged product, allows product visibility, and also helps recyclability after the product life cycle. However, the solution needs to remain commercially viable and technically feasible for easy adaptation of technology at the manufacturing location of such packaging material.

5.1.2 Rigid plastics packing Rigid plastics packaging made from Poly Ethylene, Poly Propylene (PP), and Poly Ethylene Terephthalate (PET) enables 100% recycling of the

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packaging material (both in process wastage and rejections, as well as postconsumer wastes). With the advent of multilayer injection moulding machines, plastic moulding operations are now capable of operating virtually at 0% material waste. These machines are capable of even utilizing postconsumer wastes for production of fresh outputs. However, compared with the flexible packaging material, rigid plastics packaging suffers two clear disadvantages as listed below: (i) They consume higher quantity of material per gram of product packed (ii) They do not extend effective barrier to product packed, in comparison with flexible laminate with aluminum as sandwich layer. Downsizing the thickness of the articles is a possible option to achieve reduced material consumption per gram of product packed in rigid plastics packaging. However, such reduced thickness in turn results in poor functional properties of articles produced. Usage of nanoparticles along with the polymeric compounds can help to address both the concerns above, by improving mechanical, barrier, and functional properties of the packaging articles while enabling light weighting by thinning down the structure. Nanocomposites offer unusual combinations of mechanical properties and weight that are difficult to attain separately from the individual components. Compared to conventional composites, nanocomposites have ultrafine nanometer size phase dimensions and offer unique combination of properties due to their size. Nanocomposites thus open up the possibility of downsizing the package thickness while improving the mechanical properties. Therefore, this new class of materials offers advanced technology and business opportunities. This research work is aimed to make use of the developing field of nanocomposites along with the conventional injection moulding process for producing injection-moulded components with improved mechanical, physical, and functional properties.

5.2 Literature review Various literatures are studied to understand the extent of research work carried out on usage of nanoparticles in plastics processing and the possibility of extending such options to processing of polymeric material for packaging applications. A summary of review of literature and inferences derived is listed below. Nanoparticles offer several advantages over microparticles due to their interfacial interactions on polymer branches, increased surface area and aspect ratio, high surface energy, and therefore, improved mechanical,

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thermal, and barrier properties of polymers. Barrier function of a plastic packaging can be improved either by adding a layer of barrier material or by incorporating barrier material with the base polymer by adding it during the processing stage [6]. Polymer nanocomposite is a material consisting of a mixture of two or more phase-separated material, where at least one of the dispersed phases is in nanoscale and has a polymeric major phase. Nanoscale material will have one of the three external dimensions in the range of 1 nm to 100 nm. Nanocomposites thus formed provide substantial improvement in their properties even at low nanoparticle content [7]. Performance of such nanocomposites depends on the size of nanoparticles used in the formulation of nanocomposites, aspect ratio, specific surface area, volume fraction used, compatibility with the matrix, and dispersion of nanoparticles in the composite structure [8]. Because of the nano size of the particles and with moderate filler levels, the resulting material in most cases remains transparent. Improved barrier properties of the order of 50 or higher can be achieved with high aspect ratio filler particles (Fig. 5.2). Different types of clays can be employed as filler material, and any suitable polymer is employed as the matrix [6]. Presence of nanoparticles in the nanocomposites offers several advantages like reduced amount of material needed for improved performance, increased tensile strength, improved thermal stability, improved flame retardance, enhanced barrier properties against gas permeation, UV radiations, moisture, and volatile organic compounds [10]. Polyethylene Terephthalate film coated with Silicon Oxide (SiOx) and Aluminum Oxide (AlOx) nanoparticles is already being used, though for a limited extent, in

Fig. 5.2 Schematic representation of the increasing surface while decreasing the particle size [9].

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Table 5.2 Barrier properties of common flexible packaging Oxygen permeability at 23°C 50% or 0% RH [cm3 mm/(m2 day atm)] Polymer

films [6]. Water vapor permeability at 23°C 85% RH [g mm/(m2 day)]

Poly(ethylene terephthalate) (PET) Polypropylene (PP) Polyethylene (PE) Polystyrene (PS) Poly(vinyl chloride) (PVC) Poly(ethylene naphthalate) (PEN) Polyamide (PA) Poly(vinyl alcohol) (PVAL) Ethylene vinyl alcohol (EVOH) Poly(vinylidene chloride) (PVDC)

1–5

0.5–2

50–100 50–200 100–150 2–8 0.5

0.2–0.4 0.5–2 1–4 1–2 0.7

0.1–1 (dry) 0.02 (dry) 0.001–0.01 (dry)

0.5–10 30 1–3

0.01–0.3

0.1

flexible packaging material for food packaging applications. Barrier provided by SiOx- and AlOx-coated films commercially available as of now is inferior to aluminum foil, and hence, is still not a preferred choice as complete replacement of aluminum foil for food packaging companies, especially for aggressive applications. Some comparative barrier figures are shown in Tables 5.2–5.5. Incorporating nanoparticles in the packaging material structure enables improved barrier properties of the film, as the coating of nanoparticles Table 5.3 Barrier properties of rigid containers [6]. Container composition Oxygen transmission rate at 23°C and size 50% RH [cm3/(pack day atm)]

PP. 900 mL PP/PA, 530 mL PP/EVOH/PP, 300 mL HDPE, 500 mL HDPE/PA, 500 mL HDPE/EVOH/HDPE, 650 mL PET, 500 mL PET/PA, 500 mL PET/EVOH/PET, 500 mL

6 0.4 0.2 4 0.3–0.4 0.1–0.2 0.2–0.4 0.1–0.2 0.1

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Table 5.4 Barrier properties of common flexible packaging laminates [6]. Water vapor transmission Oxygen transmission rate at 23°C 85% RH rate at 23°C 50% RH [g/m2 day] [cm3/m2 day atm] Polymera

PET PET PET PET PET

12/Alu 9/PE 50 12/Alu met./PE 50 12/EVOH 5/PE 50 12/PVAL 3/PE 50 12/PE 50

0 1–2 1 2 15–20

0 0.1–0.5 2–4 4–6 4–6

a

Polymer abbreviations are defined in Table 5.1. The number after each polymer is the layer thickness in microns.

Table 5.5 Barrier properties of common nanoparticle-coated films. Typical O2 transmission Typical water vapor transmission rate @ 23°C rate @ 23°C 50% Construction 85% RH gm/m2 per day RH cm3/m2 per day

SiOx-coated PET – 12 μ AlOx-coated PET – 12 μ SiOx-coated oriented PP – 18 μ

0.30–0.50 0.10–0.20