iii Preface A majority of commercial and military indus- tries require engineers, designers, and anyone involved in product defi nition to be knowledgeable in proper dimensioning and tolerancing methods. This knowledge is important in product design, production equipment design, and tooling design. These industries also require many employees who work in the procurement and manufacturing of parts to understand and interpret dimensions and tolerances. Machinists, machine programming per- sonnel, tool makers, inspectors, and manufacturing engineers should understand dimensions and toler- ances because they work to the specifi cations created by the engineers and designers. Requirements for consistent and clear appli- cation of dimensions and tolerances are defi ned by national standards developed by the American Society of Mechanical Engineers (ASME). There are also standards written by the International Organization for Standardization (ISO) that defi ne dimensioning and tolerancing requirements and are used in some countries. The ISO methods are similar to ASME standards, but there are signifi cant detailed differences. Care should be taken to never reference both ISO and ASME dimensioning and tolerancing standards in the same product defi nition. ISO stan- dards have established altered defi nitions of require- ments for some ASME symbols, such as position. Proper application of dimensions and tolerances is an important part of providing complete documen- tation of product requirements. ASME Y14.5 is the authoritative document for defi ning dimensioning and tolerancing symbols and application methods. ASME Y14.41 provides further explanation specifi - cally applicable to product defi nition data sets devel- oped using computer-aided design processes. GD&T: Application and Interpretation provides an expanded explanation of the principles contained in the applicable ASME standards. Coverage in this text ranges from the fundamentals of dimension application to extended principles of tolerance application. It provides introductory information on GD&T for an entry-level class while also providing the information needed for in-depth understand- ing and use as a reference book in education and industry. Although the importance of dimension- ing fundamentals is reduced by the utilization of undimensioned CAD models in product defi nition, this text continues to provide an explanation of the fundamentals because some companies still create fully dimensioned product defi nition even when they develop a model. Tolerance application and interpretation expla- nations in this textbook are included for all of the categories of tolerances in ASME Y14.5. Explanations are primarily based on the current version of the standard, ASME Y14.5-2018. Past practices are briefl y explained to provide information for situations where documentation from the past is encountered. Past practices, where included in this text, are clearly distinguished from current practices. GD&T: Application and Interpretation con- tains 12 chapters. A list of objectives is provided at the beginning of each chapter. A chapter sum- mary is given at the end of each chapter. Chapter review materials include questions and application problems. Additional questions and problems are available in the Study Guide and in the assessment software question banks, which contain approxi- mately 1700 questions. Throughout this book, specifi c terminology is used as defi ned by national standards and is consistent with terms commonly used in industry. Usage of specifi c terminology is required to provide an accurate explanation of tolerance application and interpretation. Generally, technical terms are italicized when they fi rst appear and are defi ned within the text. Defi nitions are also given in the Glossary to permit easy reference. After a detailed technical term is defi ned, further application of the term may be simplifi ed. As an example, an explanation may refer to the “axis” of a hole, instead of using a complex reference to the “axis of the unrelated actual mating envelope.” Simplifi cation is possible for this example because the term “axis” in the context of a cylindrical feature is defi ned as being the “axis of the unrelated actual mating envelope.” Illustrations are used extensively to clarify explanations. Each fi gure generally introduces only one new concept. Figures are not complicated with detail that is unrelated to the concept being explained, so they are not complete drawings. This makes it possible for the reader to quickly see the necessary information. Color is used to separate explanation data from the main portion of a fi gure. Color is also used to highlight instructional information such as toler- ance placement requirements and tolerance zone