Engineering Design

TO THE GERMAN EDITION This book is addressed to those engineering students who are prepared to work-not to such as are content to refurbish existing designs without taking the trouble to understand the trains of thought and the considerations which are needed in true design work. It is a well-established fact that the beginner, confronted by the simplest of design problems, and lacking a pattern or model to suggest a solution, loses his way in endless trial and error unless given positive guidance. In this book, therefore, the author has drawn on his long teaching experience in an attempt to present in a readily understandable and systematic manner a methodical work­ plan which will enable the beginner practising design problems to reach his objective by a rational route. This approach has the further advantage. con­ firmed by experience, that in adopting it the student will find his interest and pleasure in design work growing, and his self-confidence increasing. Written with the requirements of general mechanical engineering in mind, the book does not deal with the manufacturing methods typical of light precision engineering. To prevent the book from taking on a size which would have detracted from its clear layout and obscured the main principles presented, the numerical tables, graphs, etc. available for reference in pocket books and textbooks have been omitted.

The Significance of Design.- 1| General Aspects of the Designer’s Work.- What is meant by design?.- What kinds of design work are there?.- Organization of the drawing office.- Relationship between the drawing office and other departments.- Why teach design as a special subject?.- 2| The Designer.- Qualities required in a designer.- What is a designer expected to know?.- 3| Design Factors.- A rational working plan for the drawing office.- What are the factors influencing design?.- How can one classify these factors clearly?.- 4| A Planned Policy for the Designer.- A The Systematic Working Plan.- B The Problem to be Solved.- The types of problem to be solved.- Exercise problems 1, 2.- C The Basic Design.- How are the various possible solutions found?.- How is the best solution found?.- The evaluation scheme.- Exercise problems 3–7.- D Materials.- Which factors determine the choice of material?.- How should one choose the material?.- Principal materials used.- Ferrous metals.- Non-ferrous metals.- E Manufacture.- The factors influencing manufacture?.- F Form Design.- What does the designer have to bear in mind in form design?.- General points regarding form design.- 1 How the basic design influences form design.- 2 How mechanical loading influences form design.- Rules.- Exercise problems 8 and 9.- 3 Influence of material on form design.- 4 How the production method influences form design.- (a) Form design of grey iron castings.- Rules.- Exercise problems 10–15.- (b) Form design of steel castings.- Rules.- Exercise problems 16 and 17.- (c) Form design of malleable iron castings.- Rules.- Non-ferrous alloys.- (d) Form design of aluminium castings.- Rules.- Exercise problem 18.- (e) Form design of pressure die castings.- Rules.- (f) Form design of plastics mouldings.- Rules.- (g) Form design of welded fabrications.- General.- Welding processes.- Gas or arc welding.- Weld forms.- Stresses.- Measures to combat contraction stress.- Joints used in welding 138.- Weldability of steels.- Design of welded structures.- Rules.- Exercise problems 19–23.- (h) Form design of forgings.- Hammer forging.- Principles of form design.- Rules.- Exercise problems 24–26.- Drop forging.- Rules.- Casting, forging, or welding?.- (i) Designing for manufacture by machining methods.- Designing for machinability.- Designing for economy.- Designing for clampability.- Designing for existing tool equipment.- Designing to avoid redundant fits.- Designing for accessibility.- Designing for ease of assembly.- 5 How the space factor influences form design.- Exercise problems 27 and 28.- 6 How size influences form design.- 7 How weight influences form design (lightweight construction).- (a) Optimization of form (lightweight construction).- Rules.- Exercise problem 29.- (b) Best possible estimate of strength.- (c) Use of welding instead of riveting.- Exercise problem 30.- (d) Use of welding instead of casting (lightweight construction in steel).- Exercise problem 31.- (e) Use of high-grade steel.- Exercise problem 32.- (f) Use of lightweight materials.- (g) Use of special sections.- (h) Use of new components.- (i) Saving of weight through basic change of layout.- (k) Lightweight construction by appropriate choice of parameter.- 8 How the use of standard components influences form design.- 9 How existing products influence form design.- 10 How appearance influences form design.- 11 How convenience of handling influences form design.- 12 How maintenance questions influence form design.- 13 How the question of repair influences form design.- 14 How surface properties influence form design.- 15 How fitness for shipment influences form design.- 16 How power requirements influence form design.- G Costs.- A Solutions of Exercise Problems.- B Bibliography.- C British Standard Specifications of Materials.- D Strength of Cast Iron.