Emerald Group Publishing Limited
Copyright © 2008, Emerald Group Publishing Limited
Product Design for Manufacture and Assembly
Article Type: Book review From: Assembly Automation, Volume 28, Issue 3
Geoffrey Boothroyd, Peter Dewhurst and Winston A. Knight,2nd edition (Hardcover),CRC Press/Taylor & Francis Group (www.crcpress.com),$169.95/£90.00,720 pp.,ISBN 0-8247-0584-X,
If you are a manufacturer needing to reduce the cost of your products in a highly competitive international market, go out and buy this book. If you are a manufacturing student looking to learn something that will increase your value to potential employers, go out and buy this book. If you are a design engineer who wants to “make for a penny, what any fool can make for two” then go out and buy this book.
This new edition of Product Design for Manufacture and Assembly is a distillation of a lifetimes work for the authors. Although the book looks like a text book and is written by well respected academics, it is more than just academic. The book works on three levels. It describes and illustrates a design philosophy that applies a scoring model to just about every manufacturing activity. However, it is not a “Five minute manager” type of book: it is underpinned with sound rigorous principles and a lifetime of collecting data. Thus, it works at a philosophical level and at an academic level by presenting detailed costing models of a wide range of manufacturing processes. I confess, I go for the principles and the summaries of design guidelines and skip the detailed models but other readers should not be put off by the equations. In bypassing the equations I may fail to shave off every penny but I am usually content with the design directions given by the approach. Finally, and most importantly, it is a practical book, it works spectacularly well in the real world. I know it is practically valuable because I have personally applied the approach to the reduction of cost for a range of products, including domestic appliances, automotive components, furniture, ships compasses, carpet making machinery; the list goes on, transformers, lighting units, etc.
So, what will you find in this book? The book is logically laid out, starting with a couple of chapters of introduction, which could be skipped by most readers with some background in manufacturing. The usefulness of the book ramps up steeply with the section on the mechanical assembly process using automation and manual assembly. Starting with assembly processes reflects the route the authors took throughout the development of the book and will also predict the route that will be required in most design for manufacture projects. That is, Boothroyd, who almost single-handedly turned the “skill” of mechanical assembly into a scientific discipline, started with an interest in automatic and then manual assembly. He found that design for assembly, particularly, part count reduction, led to the redesign of component parts. This carries the danger that savings made in the assembly process can result in increased component cost. The next logical step for the authors was to systematically investigate component costs. Just as the book takes a feature-based approach to the costing of assembly it takes a similar approach to the design of individual components. In any project the designer will be required to pass through the redesign process iteratively, considering concurrently the assembly and component costs.
The following chapters deal with the common manufacturing processes such as machining, injection moulding, sheet metalworking, casting and forging. The sections on sand casting, investment casting and hot forging are new to this second edition. Each of the chapters has a similar structure, which starts with an introduction to the processes. The introductions given are not detailed but intended to give sufficient basis for understanding their various costing models. The introductions are illustrated with numerous case studies and illustrations. Other new material can be found in the introductory chapters where they fill out the descriptions rather than adding anything substantially new.
Without doubt, the most important aspect of the book are the costing models which form the basis of process selection tables and lead to the design rules that end each of the process chapters. Newer and interesting work is covered in the chapters on electrical connections and wire harness assembly and printed circuit board design. I intend to spend some quality time on these chapters.
Ernie AppletonDurham Pipeline Technology Ltd, Gateshead, UK