Additive Manufacturing Technologies PDF

Ian Gibson · David Rosen Brent Stucker Additive Manufacturing Technologies 3D Printing, Rapid Prototyping, and Direct Digital Manufacturing Second Edition Additive Manufacturing Technologies Ian Gibson • David Rosen • Brent Stucker Additive Manufacturing Technologies 3D Printing, Rapid Protot...

Ian Gibson · David Rosen Brent Stucker Additive Manufacturing Technologies 3D Printing, Rapid Prototyping, and Direct Digital Manufacturing Second Edition Additive Manufacturing Technologies Ian Gibson • David Rosen • Brent Stucker Additive Manufacturing Technologies 3D Printing, Rapid Prototyping, and Direct Digital Manufacturing Second Edition Ian Gibson School of Engineering Deakin University Victoria, Australia David Rosen George W. Woodruff School of Mechanical Engineering Georgia Institute of Technology Atlanta, GA USA Brent Stucker Department of Industrial Engineering, J B Speed University of Louisville Louisville, KY USA ISBN 978-1-4939-2112-6 ISBN 978-1-4939-2113-3 (eBook) DOI 10.1007/978-1-4939-2113-3 Springer New York Heidelberg Dordrecht London Library of Congress Control Number: 2014953293 # Springer Science+Business Media New York 2010, 2015 This work is subject to copyright. 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Violations are liable to prosecution under the respective Copyright Law. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com) Preface Thank you for taking the time to read this book on Additive Manufacturing (AM). We hope you benefit from the time and effort it has taken putting it together and that you think it was a worthwhile undertaking. It all started as a discussion at a conference in Portugal when we realized that we were putting together books with similar aims and objectives. Since we are friends as well as colleagues, it seemed sensible that we join forces rather than compete; sharing the load and playing to each other’s strengths undoubtedly means a better all-round effort and result. We wrote this book because we have all been working in the field of AM for many years. Although none of us like to be called “old,” we do seem to have 60 years of experience, collectively, and have each established reputations as educators and researchers in this field. We have each seen the technologies described in this book take shape and develop into serious commercial tools, with tens of thousands of users and many millions of parts being made by AM machines each year. AM is now being incorporated into curricula in many schools, polytechnics, and universities around the world. More and more students are becoming aware of these technologies and yet, as we saw it, there was no single text adequate for such curricula. We believe that the first edition of this book provided such a text, and based upon the updated information in this 2nd edition, we hope we’ve improved upon that start. Additive Manufacturing is defined by a range of technologies that are capable of translating virtual solid model data into physical models in a quick and easy process. The data are broken down into a series of 2D cross-sections of a finite thickness. These cross-sections are fed into AM machines so that they can be combined, adding them together in a layer-by-layer sequence to form the physical part. The geometry of the part is therefore clearly reproduced in the AM machine without having to adjust for manufacturing processes, like attention to tooling, undercuts, draft angles, or other features. We can say therefore that the AM machine is a What You See Is What You Build (WYSIWYB) process that is particularly valuable the more complex the geometry is. This basic principle drives nearly all AM machines, with variations in each technology in terms of the techniques used for creating layers and in bonding them together. Further variations v vi Preface include speed, layer thickness, range of materials, accuracy, and of course cost. With so many variables, it is clear to see why this book must be so long and detailed. Having said that, we still feel there is much more we could have written about. The first three chapters of this book provide a basic overview of AM processes. Without fully describing each technology, we provide an appreciation for why AM is so important to many branches of industry. We outline the rapid development of this technology from humble beginnings that showed promise but still requiring much development, to one that is now maturing and showing real benefit to product development organizations. In reading these chapters, we hope you can learn the basics of how AM works. The next nine chapters (Chaps. 4–12) take each group of technologies in turn and describe them in detail. The fundamentals of each technology are dealt with in terms of the basic process, whether it involves photopolymer curing, sintering, melting, etc., so that the reader can appreciate what is needed in order to understand, develop, and optimize each technology. Most technologies discussed in this book have been commercialized by at least one company; and these machines are described along with discussion on how to get the best out of them. The last chapter in this group focused on inexpensive processes and machines, which overlaps some of the material in earlier chapters, but we felt that the exponentially increasing interest in these low-cost machines justified the special treatment. The final chapters deal with how to apply AM technology in different settings. Firstly, we look at selection methods for sorting through the many options concerning the type of machine you should buy in relation to your application and provide guidelines on how to select the right technology for your purpose. Since all AM machines depend on input from 3D CAD software, we go on to discuss how this process takes place. We follow this with a discussion of postprocessing methods and technologies so that if your selected machine and material cannot produce exactly what you want, you have the means for improving the part’s properties and appearance. A chapter on software issues in AM completes this group of chapters. AM technologies have improved to the extent that many manufacturers are using AM machine output for end-product use. Called Direct Digital Manufacturing, this opens the door to many exciting and novel applications considered impossible, infeasible, or uneconomic in the past. We can now consider the possibility of mass customization, where a product can be produced according to the tastes of an individual consumer but at a cost-effective price. Then, we look at how the use of this technology has affected the design process considering how we might improve our designs because of the WYSIWYB approach. This moves us on nicely to the subjects of applications of AM, including tooling and products in the medical, aerospace, and automotive industries. We complete the book with a chapter on the business, or enterprise-level, aspects of AM, investigating how these systems Preface vii enable creative businesses and entrepreneurs to invent new products, and where AM will likely develop in the future. This book is primarily aimed at students and educators studying Additive Manufacturing, either as a self-contained course or as a module within a larger course on manufacturing technology. There is sufficient depth for an undergraduate or graduate-level course, with many references to point the student further along the path. Each chapter also has a number of exercise questions designed to test the reader’s knowledge and to expand their thinking. A companion instructor’s guide is being developed as part of the 2nd edition to include additional exercises and their solutions, to aid educators. Researchers into AM may also find this text useful in helping them understand the state of the art and the opportunities for further research. We have made a wide range of changes in moving from the first edition, completed in 2009, to this new edition. As well as bringing everything as up to date as is possible in this rapidly changing field, we have added in a number of new sections and chapters. The chapter on medical applications has been extended to include discussion on automotive and aerospace. There is a new chapter on rapid tooling as well as one that discusses the recent movements in the low-cost AM sector. We have inserted a range of recent technological innovations, including discussion on the new Additive Manufacturing File Format as well as other inclusions surrounding the standardization of AM with ASTM and ISO. We have also updated the terminology in the text to conform to terminology developed by the ASTM F42 committee, which has also been adopted as an ISO international standard. In this 2nd edition we have edited the text to, as much as possible, remove references to company-specific technologies and instead focus more on technological principles and general understanding. We split the original chapter on printing processes into two chapters on material jetting and on binder jetting to reflect the standard terminology and the evolution of these processes in different directions. As a result of these many additions and changes, we feel that this edition is now significantly more comprehensive than the first one. Although we have worked hard to make this book as comprehensive as possible, we recognize that a book about such rapidly changing technology will not be up-todate for very long. With this in mind, and to help educators and students better utilize this book, we will update our course website at http://www.springer.com/ 978-1-4419-1119-3, with additional homework exercises and other aids for educators. If you have comments, questions, or suggestions for improvement, they are welcome. We anticipate updating this book in the future, and we look forward to hearing how you have used these materials and how we might improve this book. viii Preface As mentioned earlier, each author is an established expert in Additive Manufacturing with many years of research experience. In addition, in many ways, this book is only possible due to the many students and colleagues with whom we have collaborated over the years. To introduce you to the authors and some of the others who have made this book possible, we will end this preface with brief author biographies and acknowledgements. Singapore, Singapore Atlanta, GA, USA Louisville, KY, USA Ian Gibson David Rosen Brent Stucker Acknowledgements Dr. Brent Stucker thanks Utah State and VTT Technical Research Center of Finland, which provided time to work on the first edition of this book while on sabbatical in Helsinki; and more recently the University of Louisville for providing the academic freedom and environment needed to complete the 2nd edition. Additionally, much of this book would not have been possible without the many graduate students and postdoctoral researchers who have worked with Dr. Stucker over the years. In particular, he would like to thank Dr. G.D. Janaki Ram of the Indian Institute of Technology Madras, whose coauthoring of the “Layer-Based Additive Manufacturing Technologies” chapter in the CRC Materials Processing Handbook helped lead to the organization of this book. Additionally, the following students’ work led to one or more things mentioned in this book and in the accompanying solution manual: Muni Malhotra, Xiuzhi Qu, Carson Esplin, Adam Smith, Joshua George, Christopher Robinson, Yanzhe Yang, Matthew Swank, John Obielodan, Kai Zeng, Haijun Gong, Xiaodong Xing, Hengfeng Gu, Md. Anam, Nachiket Patil, and Deepankar Pal. Special thanks are due to Dr. Stucker’s wife Gail, and their children: Tristie, Andrew, Megan, and Emma, who patiently supported many days and evenings on this book. Prof. David W. Rosen acknowledges support from Georgia Tech and the many graduate students and postdocs who contributed technically to the content in this book. In particular, he thanks Drs. Fei Ding, Amit Jariwala, Scott Johnston, Ameya Limaye, J. Mark Meacham, Benay Sager, L. Angela Tse, Hongqing Wang, Chris Williams, Yong Yang, and Wenchao Zhou, as well as Lauren Margolin and Xiayun Zhao. A special thanks goes out to his wife Joan and children Erik and Krista for their patience while he worked on this book. Prof. Ian Gibson would like to acknowledge the support of Deakin University in providing sufficient time for him to work on this book. L.K. Anand also helped in preparing many of the drawings and images for his chapters. Finally, he wishes to thank his lovely wife, Lina, for her patience, love, and understanding during the long hours preparing the material and writing the chapters. He also dedicates this book to his late father, Robert Ervin Gibson, and hopes he would be proud of this wonderful achievement. ix Contents 1 Introduction and Basic Principles . . . . . . . . . . . . . . . . . . . . . . . . . . 1.1 What Is Additive Manufacturing? . . . . . . . . . . . . . . . . . . . . . 1.2 What Are AM Parts Used for? . . . . . . . . . . . . . . . . . . . . . . . . 1.3 The Generic AM Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3.1 Step 1: CAD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3.2 Step 2: Conversion to STL . . . . . . . . . . . . . . . . . . . 1.3.3 Step 3: Transfer to AM Machine and STL File Manipulation . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3.4 Step 4: Machine Setup . . . . . . . . . . . . . . . . . . . . . . 1.3.5 Step 5: Build . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3.6 Step 6: Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.3.7 Step 7: Post-processing . . . . . . . . . . . . . . . . . . . . . . 1.3.8 Step 8: Application . . . . . . . . . . . . . . . . . . . . . . . . . 1.4 Why Use the Term Additive Manufacturing? . . . . . . . . . . . . . 1.4.1 Automated Fabrication (Autofab) . . . . . . . . . . . . . . 1.4.2 Freeform Fabrication or Solid Freeform Fabrication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4.3 Additive Manufacturing or Layer-Based Manufacturing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.4.4 Stereolithography or 3D Printing . . . . . . . . . . . . . . . 1.4.5 Rapid Prototyping . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 The Benefits of AM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6 Distinction Between AM and CNC Machining . . . . . . . . . . . . 1.6.1 Material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6.2 Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6.3 Complexity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6.4 Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6.5 Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.6.6 Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.7 Example AM Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8 Other Related Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8.1 Reverse Engineering Technology . . . . . . . . . . . . . . 1.8.2 Computer-Aided Engineering . . . . . . . . . . . . . . . . . 1 1 3 4 4 4 5 5 5 6 6 6 7 7 7 7 8 8 9 10 10 10 11 11 12 12 12 14 14 15 xi xii 2 3 Contents 1.8.3 Haptic-Based CAD . . . . . . . . . . . . . . . . . . . . . . . . 1.9 About this Book . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.10 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 17 17 18 Development of Additive Manufacturing Technology . . . . . . . . . . 2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.2 Computers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.3 Computer-Aided Design Technology . . . . . . . . . . . . . . . . . . 2.4 Other Associated Technologies . . . . . . . . . . . . . . . . . . . . . . 2.4.1 Lasers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.2 Printing Technologies . . . . . . . . . . . . . . . . . . . . . . 2.4.3 Programmable Logic Controllers . . . . . . . . . . . . . . 2.4.4 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.4.5 Computer Numerically Controlled Machining . . . . 2.5 The Use of Layers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.6 Classification of AM Processes . . . . . . . . . . . . . . . . . . . . . . 2.6.1 Liquid Polymer Systems . . . . . . . . . . . . . . . . . . . . 2.6.2 Discrete Particle Systems . . . . . . . . . . . . . . . . . . . 2.6.3 Molten Material Systems . . . . . . . . . . . . . . . . . . . 2.6.4 Solid Sheet Systems . . . . . . . . . . . . . . . . . . . . . . . 2.6.5 New AM Classification Schemes . . . . . . . . . . . . . . 2.7 Metal Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.8 Hybrid Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.9 Milestones in AM Development . . . . . . . . . . . . . . . . . . . . . 2.10 AM Around the World . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.11 The Future? Rapid Prototyping Develops into Direct Digital Manufacturing . . . . . . . . . . . . . . . . . . . . . . . . 2.12 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 19 20 22 26 26 26 27 27 28 28 30 31 32 33 34 34 35 36 37 39 . . . 40 41 41 Generalized Additive Manufacturing Process Chain . . . . . . . . . . 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2 The Eight Steps in Additive Manufacture . . . . . . . . . . . . . . . 3.2.1 Step 1: Conceptualization and CAD . . . . . . . . . . . 3.2.2 Step 2: Conversion to STL/AMF . . . . . . . . . . . . . . 3.2.3 Step 3: Transfer to AM Machine and STL File Manipulation . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.4 Step 4: Machine Setup . . . . . . . . . . . . . . . . . . . . . 3.2.5 Step 5: Build . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.2.6 Step 6: Removal and Cleanup . . . . . . . . . . . . . . . . 3.2.7 Step 7: Post-Processing . . . . . . . . . . . . . . . . . . . . . 3.2.8 Step 8: Application . . . . . . . . . . . . . . . . . . . . . . . . 3.3 Variations from One AM Machine to Another . . . . . . . . . . . 3.3.1 Photopolymer-Based Systems . . . . . . . . . . . . . . . . . . . . . 43 43 44 44 45 . . . . . . . . 47 47 48 48 49 49 50 51 Contents 3.3.2 Powder-Based Systems . . . . . . . . . . . . . . . . . . . . . 3.3.3 Molten Material Systems . . . . . . . . . . . . . . . . . . . 3.3.4 Solid Sheets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4 Metal Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.1 The Use of Substrates . . . . . . . . . . . . . . . . . . . . . . 3.4.2 Energy Density . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.3 Weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.4 Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.4.5 Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.5 Maintenance of Equipment . . . . . . . . . . . . . . . . . . . . . . . . . 3.6 Materials Handling Issues . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7 Design for AM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7.1 Part Orientation . . . . . . . . . . . . . . . . . . . . . . . . . . 3.7.2 Removal of Supports . . . . . . . . . . . . . . . . . . . . . . 3.7.3 Hollowing Out Parts . . . . . . . . . . . . . . . . . . . . . . . 3.7.4 Inclusion of Undercuts and Other Manufacturing Constraining Features . . . . . . . . . . . . . . . . . . . . . . 3.7.5 Interlocking Features . . . . . . . . . . . . . . . . . . . . . . 3.7.6 Reduction of Part Count in an Assembly . . . . . . . . 3.7.7 Identification Markings/Numbers . . . . . . . . . . . . . 3.8 Application Areas That Don’t Involve Conventional CAD Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.8.1 Medical Modeling . . . . . . . . . . . . . . . . . . . . . . . . 3.8.2 Reverse Engineering Data . . . . . . . . . . . . . . . . . . . 3.8.3 Architectural Modeling . . . . . . . . . . . . . . . . . . . . . 3.9 Further Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3.9.1 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 xiii . . . . . . . . . . . . . . . 51 51 52 52 53 53 53 53 54 54 54 55 55 56 57 . . . . 57 57 58 58 . . . . . . . 59 59 59 60 60 61 61 Vat Photopolymerization Processes . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2 Vat Photopolymerization Materials . . . . . . . . . . . . . . . . . . . . 4.2.1 UV-Curable Photopolymers . . . . . . . . . . . . . . . . . . 4.2.2 Overview of Photopolymer Chemistry . . . . . . . . . . . 4.2.3 Resin Formulations and Reaction Mechanisms . . . . . 4.3 Reaction Rates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.4 Laser Scan Vat Photopolymerization . . . . . . . . . . . . . . . . . . . 4.5 Photopolymerization Process Modeling . . . . . . . . . . . . . . . . . 4.5.1 Irradiance and Exposure . . . . . . . . . . . . . . . . . . . . . 4.5.2 Laser–Resin Interaction . . . . . . . . . . . . . . . . . . . . . 4.5.3 Photospeed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5.4 Time Scales . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6 Vector Scan VP Machines . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7 Scan Patterns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7.1 Layer-Based Build Phenomena and Errors . . . . . . . . 63 63 65 66 67 70 73 74 74 75 78 80 81 82 84 84 xiv 5 Contents 4.7.2 WEAVE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7.3 STAR-WEAVE . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7.4 ACES Scan Pattern . . . . . . . . . . . . . . . . . . . . . . . 4.8 Vector Scan Micro-Vat Photopolymerization . . . . . . . . . . . . 4.9 Mask Projection VP Technologies and Processes . . . . . . . . . 4.9.1 Mask Projection VP Technology . . . . . . . . . . . . . . 4.9.2 Commercial MPVP Systems . . . . . . . . . . . . . . . . . 4.9.3 MPVP Modeling . . . . . . . . . . . . . . . . . . . . . . . . . 4.10 Two-Photon Vat Photopolymerization . . . . . . . . . . . . . . . . . 4.11 Process Benefits and Drawbacks . . . . . . . . . . . . . . . . . . . . . 4.12 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.13 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 88 90 94 95 95 96 98 99 101 102 102 103 Powder Bed Fusion Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.2.1 Polymers and Composites . . . . . . . . . . . . . . . . . . . 5.2.2 Metals and Composites . . . . . . . . . . . . . . . . . . . . . 5.2.3 Ceramics and Ceramic Composites . . . . . . . . . . . . 5.3 Powder Fusion Mechanisms . . . . . . . . . . . . . . . . . . . . . . . . 5.3.1 Solid-State Sintering . . . . . . . . . . . . . . . . . . . . . . . 5.3.2 Chemically Induced Sintering . . . . . . . . . . . . . . . . 5.3.3 LPS and Partial Melting . . . . . . . . . . . . . . . . . . . . 5.3.4 Full Melting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.3.5 Part Fabrication . . . . . . . . . . . . . . . . . . . . . . . . . . 5.4 Process Parameters and Modeling . . . . . . . . . . . . . . . . . . . . 5.4.1 Process Parameters . . . . . . . . . . . . . . . . . . . . . . . . 5.4.2 Applied Energy Correlations and Scan Patterns . . . 5.5 Powder Handling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.5.1 Powder Handling Challenges . . . . . . . . . . . . . . . . 5.5.2 Powder Handling Systems . . . . . . . . . . . . . . . . . . 5.5.3 Powder Recycling . . . . . . . . . . . . . . . . . . . . . . . . 5.6 PBF Process Variants and Commercial Machines . . . . . . . . . 5.6.1 Polymer Laser Sintering . . . . . . . . . . . . . . . . . . . . 5.6.2 Laser-Based Systems for Metals and Ceramics . . . . 5.6.3 Electron Beam Melting . . . . . . . . . . . . . . . . . . . . . 5.6.4 Line-Wise and Layer-Wise PBF Processes for Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.7 Process Benefits and Drawbacks . . . . . . . . . . . . . . . . . . . . . 5.8 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.9 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 107 109 109 110 112 112 112 115 116 120 121 122 123 125 127 127 128 129 131 131 134 136 . . . . . 140 143 144 144 145 Contents xv 6 Extrusion-Based Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2 Basic Principles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.1 Material Loading . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.2 Liquification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.3 Extrusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.4 Solidification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.5 Positional Control . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.6 Bonding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.2.7 Support Generation . . . . . . . . . . . . . . . . . . . . . . . . 6.3 Plotting and Path Control . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.4 Fused Deposition Modeling from Stratasys . . . . . . . . . . . . . . . 6.4.1 FDM Machine Types . . . . . . . . . . . . . . . . . . . . . . . 6.5 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.6 Limitations of FDM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.7 Bioextrusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.7.1 Gel Formation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.7.2 Melt Extrusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.7.3 Scaffold Architectures . . . . . . . . . . . . . . . . . . . . . . 6.8 Other Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.8.1 Contour Crafting . . . . . . . . . . . . . . . . . . . . . . . . . . 6.8.2 Nonplanar Systems . . . . . . . . . . . . . . . . . . . . . . . . . 6.8.3 FDM of Ceramics . . . . . . . . . . . . . . . . . . . . . . . . . . 6.8.4 Reprap and Fab@home . . . . . . . . . . . . . . . . . . . . . 6.9 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 147 148 149 149 149 153 154 155 156 157 160 161 163 164 166 166 166 168 168 169 169 171 171 172 173 7 Material Jetting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.1 Evolution of Printing as an Additive Manufacturing Process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2 Materials for Material Jetting . . . . . . . . . . . . . . . . . . . . . . . . . 7.2.1 Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2.2 Ceramics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2.3 Metals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.2.4 Solution- and Dispersion-Based Deposition . . . . . . . 7.3 Material Processing Fundamentals . . . . . . . . . . . . . . . . . . . . . 7.3.1 Technical Challenges of MJ . . . . . . . . . . . . . . . . . . 7.3.2 Droplet Formation Technologies . . . . . . . . . . . . . . . 7.3.3 Continuous Mode . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3.4 DOD Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.3.5 Other Droplet Formation Methods . . . . . . . . . . . . . . 7.4 MJ Process Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.5 Material Jetting Machines . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.6 Process Benefits and Drawbacks . . . . . . . . . . . . . . . . . . . . . . 7.7 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7.8 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 175 176 177 180 181 183 184 184 186 187 188 190 191 195 198 198 199 200 xvi Contents 8 Binder Jetting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.2.1 Commercially Available Materials . . . . . . . . . . . . 8.2.2 Ceramic Materials in Research . . . . . . . . . . . . . . . 8.3 Process Variations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.4 BJ Machines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.5 Process Benefits and Drawbacks . . . . . . . . . . . . . . . . . . . . . 8.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.7 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205 205 207 207 208 210 212 216 217 217 218 9 Sheet Lamination Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.1.1 Gluing or Adhesive Bonding . . . . . . . . . . . . . . . . . 9.1.2 Bond-Then-Form Processes . . . . . . . . . . . . . . . . . 9.1.3 Form-Then-Bond Processes . . . . . . . . . . . . . . . . . 9.2 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.3 Material Processing Fundamentals . . . . . . . . . . . . . . . . . . . . 9.3.1 Thermal Bonding . . . . . . . . . . . . . . . . . . . . . . . . . 9.3.2 Sheet Metal Clamping . . . . . . . . . . . . . . . . . . . . . 9.4 Ultrasonic Additive Manufacturing . . . . . . . . . . . . . . . . . . . 9.4.1 UAM Bond Quality . . . . . . . . . . . . . . . . . . . . . . . 9.4.2 Ultrasonic Metal Welding Process Fundamentals . . 9.4.3 UAM Process Parameters and Process Optimization . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.4.4 Microstructures and Mechanical Properties of UAM Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.4.5 UAM Applications . . . . . . . . . . . . . . . . . . . . . . . . 9.5 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9.6 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 219 219 220 222 224 225 226 227 228 229 230 . . . . . 235 239 242 243 243 Directed Energy Deposition Processes . . . . . . . . . . . . . . . . . . . . . 10.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.2 General DED Process Description . . . . . . . . . . . . . . . . . . . . 10.3 Material Delivery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.3.1 Powder Feeding . . . . . . . . . . . . . . . . . . . . . . . . . . 10.3.2 Wire Feeding . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4 DED Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.1 Laser Based Metal Deposition Processes . . . . . . . . 10.4.2 Electron Beam Based Metal Deposition Processes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.4.3 Other DED Processes . . . . . . . . . . . . . . . . . . . . . . 10.5 Process Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.6 Typical Materials and Microstructure . . . . . . . . . . . . . . . . . . . . . . . . . . 245 245 247 249 249 251 252 252 . . . . 256 257 257 258 10 . 233 Contents 10.7 Processing–Structure–Properties Relationships . . . . . . . . . . . 10.8 DED Benefits and Drawbacks . . . . . . . . . . . . . . . . . . . . . . . 10.9 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xvii . . . . 261 266 267 268 11 Direct Write Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 Direct Write Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3 Ink-Based DW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3.1 Nozzle Dispensing Processes . . . . . . . . . . . . . . . . . 11.3.2 Quill-Type Processes . . . . . . . . . . . . . . . . . . . . . . . 11.3.3 Inkjet Printing Processes . . . . . . . . . . . . . . . . . . . . . 11.3.4 Aerosol DW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.4 Laser Transfer DW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.5 Thermal Spray DW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.6 Beam Deposition DW . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.6.1 Laser CVD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.6.2 Focused Ion Beam CVD . . . . . . . . . . . . . . . . . . . . . 11.6.3 Electron Beam CVD . . . . . . . . . . . . . . . . . . . . . . . . 11.7 Liquid-Phase Direct Deposition . . . . . . . . . . . . . . . . . . . . . . . 11.8 Beam Tracing Approaches to Additive/Subtractive DW . . . . . 11.8.1 Electron Beam Tracing . . . . . . . . . . . . . . . . . . . . . . 11.8.2 Focused Ion Beam Tracing . . . . . . . . . . . . . . . . . . . 11.8.3 Laser Beam Tracing . . . . . . . . . . . . . . . . . . . . . . . . 11.9 Hybrid Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.10 Applications of Direct Write Technologies . . . . . . . . . . . . . . . 11.10.1 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269 269 269 270 271 273 275 276 277 280 282 282 284 284 285 286 286 287 287 287 288 290 290 12 The Impact of Low-Cost AM Systems . . . . . . . . . . . . . . . . . . . . . . 12.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.2 Intellectual Property . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.3 Disruptive Innovation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.3.1 Disruptive Business Opportunities . . . . . . . . . . . . . 12.3.2 Media Attention . . . . . . . . . . . . . . . . . . . . . . . . . . 12.4 The Maker Movement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.5 The Future of Low-Cost AM . . . . . . . . . . . . . . . . . . . . . . . . 12.6 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293 293 294 296 296 297 299 301 301 301 13 Guidelines for Process Selection . . . . . . . . . . . . . . . . . . . . . . . . . . 13.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.2 Selection Methods for a Part . . . . . . . . . . . . . . . . . . . . . . . . 13.2.1 Decision Theory . . . . . . . . . . . . . . . . . . . . . . . . . . 13.2.2 Approaches to Determining Feasibility . . . . . . . . . 13.2.3 Approaches to Selection . . . . . . . . . . . . . . . . . . . . 13.2.4 Selection Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303 303 304 304 305 307 310 xviii 14 15 Contents 13.3 13.4 13.5 Challenges of Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . Example System for Preliminary Selection . . . . . . . . . . . . . . Production Planning and Control . . . . . . . . . . . . . . . . . . . . . 13.5.1 Production Planning . . . . . . . . . . . . . . . . . . . . . . . 13.5.2 Pre-processing . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.5.3 Part Build . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.5.4 Post-processing . . . . . . . . . . . . . . . . . . . . . . . . . . 13.5.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.6 Open Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.7 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312 316 321 322 323 323 324 324 325 326 326 Post-processing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.2 Support Material Removal . . . . . . . . . . . . . . . . . . . . . . . . . . 14.2.1 Natural Support Post-processing . . . . . . . . . . . . . . 14.2.2 Synthetic Support Removal . . . . . . . . . . . . . . . . . . 14.3 Surface Texture Improvements . . . . . . . . . . . . . . . . . . . . . . 14.4 Accuracy Improvements . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.4.1 Sources of Inaccuracy . . . . . . . . . . . . . . . . . . . . . . 14.4.2 Model Pre-processing to Compensate for Inaccuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.4.3 Machining Strategy . . . . . . . . . . . . . . . . . . . . . . . 14.5 Aesthetic Improvements . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.6 Preparation for Use as a Pattern . . . . . . . . . . . . . . . . . . . . . . 14.6.1 Investment Casting Patterns . . . . . . . . . . . . . . . . . 14.6.2 Sand Casting Patterns . . . . . . . . . . . . . . . . . . . . . . 14.6.3 Other Pattern Replication Methods . . . . . . . . . . . . 14.7 Property Enhancements Using Non-thermal Techniques . . . . 14.8 Property Enhancements Using Thermal Techniques . . . . . . . 14.9 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14.10 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 329 329 329 330 331 334 334 335 . . . . . . . . . . . . 335 337 341 342 342 343 344 345 346 349 349 350 Software Issues for Additive Manufacturing . . . . . . . . . . . . . . . . . 15.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.2 Preparation of CAD Models: The STL File . . . . . . . . . . . . . 15.2.1 STL File Format, Binary/ASCII . . . . . . . . . . . . . . 15.2.2 Creating STL Files from a CAD System . . . . . . . . 15.2.3 Calculation of Each Slice Profile . . . . . . . . . . . . . . 15.2.4 Technology-Specific Elements . . . . . . . . . . . . . . . 15.3 Problems with STL Files . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.4 STL File Manipulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.4.1 Viewers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.4.2 STL Manipulation on the AM Machine . . . . . . . . . . . . . . . . . . . . 351 351 352 352 354 355 359 361 364 365 365 Contents 15.5 16 17 xix Beyond the STL File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.5.1 Direct Slicing of the CAD Model . . . . . . . . . . . . . 15.5.2 Color Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15.5.3 Multiple Materials . . . . . . . . . . . . . . . . . . . . . . . . 15.5.4 Use of STL for Machining . . . . . . . . . . . . . . . . . . 15.6 Additional Software to Assist AM . . . . . . . . . . . . . . . . . . . . 15.6.1 Survey of Software Functions . . . . . . . . . . . . . . . . 15.6.2 AM Process Simulations Using Finite Element Analysis . . . . . . . . . . . . . . . . . . . . . . . . . 15.7 The Additive Manufacturing File Format . . . . . . . . . . . . . . . 15.8 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 367 367 368 368 368 369 370 . . . . 371 372 373 374 Direct Digital Manufacturing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.1 Align Technology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.2 Siemens and Phonak . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.3 Custom Footwear and Other DDM Examples . . . . . . . . . . . . 16.4 DDM Drivers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.5 Manufacturing Versus Prototyping . . . . . . . . . . . . . . . . . . . . 16.6 Cost Estimation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.6.1 Cost Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.6.2 Build Time Model . . . . . . . . . . . . . . . . . . . . . . . . 16.6.3 Laser Scanning Vat Photopolymerization Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.7 Life-Cycle Costing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.8 Future of DDM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16.9 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 375 375 377 380 383 385 387 387 389 . . . . . 392 393 395 396 397 Design for Additive Manufacturing . . . . . . . . . . . . . . . . . . . . . . . 17.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.2 Design for Manufacturing and Assembly . . . . . . . . . . . . . . . 17.3 AM Unique Capabilities . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.3.1 Shape Complexity . . . . . . . . . . . . . . . . . . . . . . . . 17.3.2 Hierarchical Complexity . . . . . . . . . . . . . . . . . . . . 17.3.3 Functional Complexity . . . . . . . . . . . . . . . . . . . . . 17.3.4 Material Complexity . . . . . . . . . . . . . . . . . . . . . . . 17.4 Core DFAM Concepts and Objectives . . . . . . . . . . . . . . . . . 17.4.1 Complex Geometry . . . . . . . . . . . . . . . . . . . . . . . 17.4.2 Integrated Assemblies . . . . . . . . . . . . . . . . . . . . . . 17.4.3 Customized Geometry . . . . . . . . . . . . . . . . . . . . . 17.4.4 Multifunctional Designs . . . . . . . . . . . . . . . . . . . . 17.4.5 Elimination of Conventional DFM Constraints . . . . . . . . . . . . . . . . . . 399 400 401 404 404 405 407 409 411 411 412 412 412 413 xx 18 19 Contents 17.5 Exploring Design Freedoms . . . . . . . . . . . . . . . . . . . . . . . . 17.5.1 Part Consolidation and Redesign . . . . . . . . . . . . . . 17.5.2 Hierarchical Structures . . . . . . . . . . . . . . . . . . . . . 17.5.3 Industrial Design Applications . . . . . . . . . . . . . . . 17.6 CAD Tools for AM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.6.1 Challenges for CAD . . . . . . . . . . . . . . . . . . . . . . . 17.6.2 Solid-Modeling CAD Systems . . . . . . . . . . . . . . . 17.6.3 Promising CAD Technologies . . . . . . . . . . . . . . . . 17.7 Synthesis Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.7.1 Theoretically Optimal Lightweight Structures . . . . 17.7.2 Optimization Methods . . . . . . . . . . . . . . . . . . . . . 17.7.3 Topology Optimization . . . . . . . . . . . . . . . . . . . . . 17.8 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.9 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 413 414 415 417 418 418 420 422 426 426 427 428 433 434 434 Rapid Tooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18.2 Direct AM Production of Injection Molding Inserts . . . . . . . 18.3 EDM Electrodes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18.4 Investment Casting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18.5 Other Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18.5.1 Vacuum Forming Tools . . . . . . . . . . . . . . . . . . . . 18.5.2 Paper Pulp Molding Tools . . . . . . . . . . . . . . . . . . 18.5.3 Formwork for Composite Manufacture . . . . . . . . . 18.5.4 Assembly Tools and Metrology Registration Rigs . . . . . . . . . . . . . . . . . . . . . . . . . 18.6 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 437 437 439 443 444 445 445 446 446 . 446 . 448 . 448 Applications for Additive Manufacture . . . . . . . . . . . . . . . . . . . . . . 19.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.2 Historical Developments . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.2.1 Value of Physical Models . . . . . . . . . . . . . . . . . . . . 19.2.2 Functional Testing . . . . . . . . . . . . . . . . . . . . . . . . . 19.2.3 Rapid Tooling . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.3 The Use of AM to Support Medical Applications . . . . . . . . . . 19.3.1 Surgical and Diagnostic Aids . . . . . . . . . . . . . . . . . 19.3.2 Prosthetics Development . . . . . . . . . . . . . . . . . . . . . 19.3.3 Manufacturing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.3.4 Tissue Engineering and Organ Printing . . . . . . . . . . 19.4 Software Support for Medical Applications . . . . . . . . . . . . . . 451 451 452 453 453 454 455 457 458 460 460 461 Contents 19.5 Limitations of AM for Medical Applications . . . . . . . . . . . . 19.5.1 Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.5.2 Cost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.5.3 Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.5.4 Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.5.5 Ease of Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.6 Further Development of Medical AM Applications . . . . . . . . 19.6.1 Approvals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.6.2 Insurance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.6.3 Engineering Training . . . . . . . . . . . . . . . . . . . . . . 19.6.4 Location of the Technology . . . . . . . . . . . . . . . . . 19.6.5 Service Bureaus . . . . . . . . . . . . . . . . . . . . . . . . . . 19.7 Aerospace Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.7.1 Characteristics Favoring AM . . . . . . . . . . . . . . . . 19.7.2 Production Manufacture . . . . . . . . . . . . . . . . . . . . 19.8 Automotive Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.9 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 xxi . . . . . . . . . . . . . . . . . . 463 464 464 465 465 466 466 466 467 467 468 468 468 469 469 472 473 474 Business Opportunities and Future Directions . . . . . . . . . . . . . . . . 20.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20.2 What Could Be New? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20.2.1 New Types of Products . . . . . . . . . . . . . . . . . . . . . . 20.2.2 New Types of Organizations . . . . . . . . . . . . . . . . . . 20.2.3 New Types of Employment . . . . . . . . . . . . . . . . . . . 20.3 Digiproneurship . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20.4 Exercises . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 475 475 477 477 479 480 481 485 486 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 487 1 Introduction and Basic Principles Abstract The technology described in this book was originally referred to as rapid prototyping. The term rapid prototyping (RP) is used in a variety of industries to describe a process for rapidly creating a system or part representation before final release or commercialization. In other words, the emphasis is on creating something quickly and that the output is a prototype or basis model from which further models and eventually the final product will be derived. Management consultants and software engineers both use the term rapid prototyping to describe a process of developing business and software solutions in a piecewise fashion that allows clients and other stakeholders to test ideas and provide feedback during the development process. In a product development context, the term rapid prototyping was used widely to describe technologies which created physical prototypes directly from digital data. This text is about these latter technologies, first developed for prototyping, but now used for many more purposes. 1.1 What Is Additive Manufacturing? Additive manufacturing is the formalized term for what used to be called rapid prototyping and what is popularly called 3D Printing. The term rapid prototyping (RP) is used in a variety of industries to describe a process for rapidly creating a system or part representation before final release or commercialization. In other words, the emphasis is on creating something quickly and that the output is a prototype or basis model from which further models and eventually the final product will be derived. Management consultants and software engineers both also use the term rapid prototyping to describe a process of developing business and software solutions in a piecewise fashion that allows clients and other stakeholders to test ideas and provide feedback during the development process. In a product development context, the term rapid prototyping was used widely to # Springer Science+Business Media New York 2015 I. Gibson et al., Additive Manufacturing Technologies, DOI 10.1007/978-1-4939-2113-3_1 1 2 1 Introduction and Basic Principles describe technologies which created physical prototypes directly from digital model data. This text is about these latter technologies, first developed for prototyping, but now used for many more purposes. Users of RP technology have come to realize that this term is inadequate and in particular does not effectively describe more recent applications of the technology. Improvements in the quality of the output from these machines have meant that there is often a much closer link to the final product. Many parts are in fact now directly manufactured in these machines, so it is not possible for us to label them as “prototypes.” The term rapid prototyping also overlooks the basic principle of these technologies in that they all fabricate parts using an additive approach. A recently formed Technical Committee within ASTM International agreed that new terminology should be adopted. While this is still under debate, recently adopted ASTM consensus standards now use the term additive manufacturing [1]. Referred to in short as AM, the basic principle of this technology is that a model, initially generated using a three-dimensional Computer-Aided Design (3D CAD) system, can be fabricated directly without the need for process planning. Although this is not in reality as simple as it first sounds, AM technology certainly significantly simplifies the process of producing complex 3D objects directly from CAD data. Other manufacturing processes require a careful and detailed analysis of the part geometry to determine things like the order in which different features can be fabricated, what tools and processes must be used, and what additional fixtures may be required to complete the part. In contrast, AM needs only some basic dimensional details and a small amount of understanding as to how the AM machine works and the materials that are used to build the part. The key to how AM works is that parts are made by adding material in layers; each layer is a thin cross-section of the part derived from the original CAD data. Obviously in the physical world, each layer must have a finite thickness to it and so the resulting part will be an approximation of the original data, as illustrated by Fig. 1.1. The thinner each layer is, the closer the final part will be to the original. All commercialized AM machines to date use a layer-based approach, and the major ways that they differ are in the materials that can be used, how the layers are created, and how the layers are bonded to each other. Such differences will determine factors like the accuracy of the final part plus its material properties and mechanical properties. They will also determine factors like how quickly the part can be made, how much post-processing is required, the size of the AM machine used, and the overall cost of the machine and process. This chapter will introduce the basic concepts of additive manufacturing and describe a generic AM process from design to application. It will go on to discuss the implications of AM on design and manufacturing and attempt to help in understanding how it has changed the entire product development process. Since AM is an increasingly important tool for product development, the chapter ends with a discussion of some related tools in the product development process. 1.2 What Are AM Parts Used for? 3 Fig. 1.1 CAD image of a teacup with further images showing the effects of building using different layer thicknesses 1.2 What Are AM Parts Used for? Throughout this book you will find a wide variety of applications for AM. You will also realize that the number of applications is increasing as the processes develop and improve. Initially, AM was used specifically to create visualization models for products as they were being developed. It is widely known that models can be much more helpful than drawings or renderings in fully understanding the intent of the designer when presenting the conceptual design. While drawings are quicker and easier to create, models are nearly always required in the end to fully validate the design. Following this initial purpose of simple model making, AM technology has developed over time as materials, accuracy, and the overall quality of the output improved. Models were quickly employed to supply information about what is known as the “3 Fs” of Form, Fit, and Function. The initial models were used to help fully appreciate the shape and general purpose of a design (Form). Improved accuracy in the process meant that components were capable of being built to the tolerances required for assembly purposes (Fit). Improved material properties meant that parts could be properly handled so that they could be assessed according to how they would eventually work (Function). 4 1 Introduction and Basic Principles To say that AM technology is only useful for making models, though, would be inaccurate and undervaluing the technology. AM, when used in conjunction with other technologies to form process chains, can be used to significantly shorten product development times and costs. More recently, some of these technologies have been developed to the extent that the output is suitable for end use. This explains why the terminology has essentially evolved from rapid prototyping to additive manufacturing. Furthermore, use of high-power laser technology has meant that parts can now also be directly made in a variety of metals, thus extending the application range even further. 1.3 The Generic AM Process AM involves a number of steps that move from the virtual CAD description to the physical resultant part. Different products will involve AM in different ways and to different degrees. Small, relatively simple products may only make use of AM for visualization models, while larger, more complex products with greater engineering content may involve AM during numerous stages and iterations throughout the development process. Furthermore, early stages of the product development process may only require rough parts, with AM being used because of the speed at which they can be fabricated. At later stages of the process, parts may require careful cleaning and post-processing (including sanding, surface preparation, and painting) before they are used, with AM being useful here because of the complexity of form that can be created without having to consider tooling. Later on, we will investigate thoroughly the different stages of the AM process, but to summarize, most AM processes involve, to some degree at least, the following eight steps (as illustrated in Fig. 1.2). 1.3.1 Step 1: CAD All AM parts must start from a software model that fully describes the external geometry. This can involve the use of almost any professional CAD solid modeling software, but the output must be a 3D solid or surface representation. Reverse engineering equipment (