E-Book Overview
This book is a comprehensive engineering exploration of all the aspects of precision machine design - both component and system design considerations for precision machines. It addresses both theoretical analysis and practical implementation providing many real-world design case studies as well as numerous examples of existing components and their characteristics. Fast becoming a classic, this book includes examples of analysis techniques, along with the philosophy of the solution method. It explores the physics of errors in machines and how such knowledge can be used to build an error budget for a machine, how error budgets can be used to design more accurate machines. Supporting software (MS Excel spreadsheets on 5.25' diskette) enable the reader to study 'What if' design scenarios based on formulas presented in the book.
E-Book Content
Chapter 1 Introduction to Precision Machine Design Why do you like to design machines? “It is the pitting of one’s brain against bits of iron, metals, and crystals and making them do what you want them to do. When you are successful that is all the reward you want.” Albert A. Michelson 1.1 I NTRODUCTION Companies can remain competitive in world markets only if they develop new technologies and methods to keep one step ahead of the competition; maintaining the status quo is not acceptable. Hence new machines need to be designed with increased speed, accuracy, and reliability. This leads to the need for designers who have a deep understanding and love of the art and science of design.1 In a broad sense, the art and science of design is a potent vitamin that must be taken in balance with other mental nutrients, such as mathematics, physics, manufacturing, hands-on experience, and business skills. Most people exercise to keep physically fit so they can enhance their enjoyment of day-to-day living. Analogous to physical exercise, analysis is a form of mental pushup that trains the mind to be strong and swift. Indeed, many designs would never have even been conceived of if the design engineer did not understand the basic physics behind the process that prompted the need for a new design. Similarly, knowing how to build things can enable the design engineer to develop easily manufacturable products that are a pleasure to use. As illustrated in Figure 1.1.1, the need to integrate various disciplines means today’s design engineer must be a Renaissance person. Design engineers must be more creative than their competition and more observant of the world around them. In today’s tough international competitive world, if you want something, you can only obtain it with blood, sweat, tears, and design. Figure 1.1.1 Increasing difficulty often leads to the integration of engineering disciplines. In the future, expert systems may evolve to replace mundane engineering tasks. However, it is unlikely that computers will ever be able to do creative design. If a computer program can be designed to do creative design, a computer program can also be designed to design new computer programs. Thus there will always be jobs for creative design engineers. However, high-paying engineering jobs will soon no longer be available for students who lack good creative and/or analytic skills.2 On the other hand, the future for bright, creative, hard-working design engineers is very promising. How can new design engineers be taught to think and be creative? Integrating theory and application with real-world considerations seems to be a good method and is stressed in following chapters. The remainder of this chapter addresses broad issues including: 1 “Enthusiasm is one of the most powerful engines of success. When you do a thing, do it with all your might. Put your whole soul into it. Stamp it with your own personality. Be active, be energetic, be enthusiastic and faithful and you will acco