by Brian Griffiths
• ISBN: 185718033X • Pub. Date: February 2003 • Publisher: Elsevier Science & Technology Books
In today's global economy, it is quite common for a component to be designed in one country, manufactured in another and assembled in yet another. The processes of manufacture and assembly are based on the communication ofengineering information via drawing. These drawings follow rules laid down in national and international standards and codes of practice. The 'highest' standards are the international ones since they allow companies to operate in global markets. The organisation which is responsible for the international rules is the International Standards Organisation (ISO). There are hundreds of ISO standards onengineering drawing and the reason is that drawing is very complicated and accurate transfer of information must be guaranteed. The information contained in an engineering drawing is actually a legal specification, which contractor and subcontractor agree to in a binding contract. The ISO standards are designed to be independent of any one language and thus much symbology is used to overcome areliance on any language. Companies can only operate efficiently if they can guarantee the correct transmission of engineering design information for manufacturing and assembly. This book is meant to be a short introduction to the subject of engineering drawing for manufacture. It is only six chapters long and each chapter has the thread of the ISO standards running through it. It should be notedthat standards are updated on a fiveyear rolling programme and therefore students of engineering drawing need to be aware of the latest standards because the goalposts move regularly! Check that books based on standards are less than five years old! A good example of the need to keep abreast of developments is the decimal marker. It is now ISO practice to use
Engineering drawing formanufacture
a comma rather than a full stop for the decimal marker. Thus, this book is unique in that it introduces the subject of engineering drawing in the context of standards. The book is divided into six chapters that follow a logical progression. The first chapter gives an overview of the principles of engineering drawing and the important concept that engineering drawing is like a language. Ithas its own rules and regulation areas and it is only when these are understood and implemented that an engineering drawing becomes a specification. The second chapter deals with the various engineering drawing projection methodologies. The third chapter introduces the concept of the ISO rules governing the representation of parts and features. A practical example is given of the drawing of a smallhand vice. The ISO rules are presented in the context of this vice such that it is experiential learning rather than theoretical. The fourth chapter introduces the methods of dimensioning and tolerancing components for manufacture. The fifth chapter introduces the concept of limits, fits and geometric tolerancing, which provides the link of dimensioning to functional performance. A link is alsomade with respect to the capability of manufacturing processes. The sixth and final chapter covers the methodology of specifying surface finish. A series of questions are given in a final section to aid the students' understanding. Full references are given at the end of each chapter so the students can pursue things further if necessary.
List of Symbols
A B f mN Ml(c) Mrl Mr2 Ra Rdc RkuRmr(c) constant constant feed per revolution amplitude distribution function moments sum of the section lengths upper material ratio lower material ratio centre line average height between two section levels of the BAC kurtosis material ratio at depth 'c' peak height RMS average skew average peak spacing EL peak to valley height valley depth SL peak to valley height RMS slope general parameter...