xii Features of the Textbook The instructional design of Geometric Dimensioning and Tolerancing includes student-focused learning tools to help you succeed. This visual guide high- lights these features. Chapter Opening Materials Each chapter opener contains a list of learning objec- tives and a list of technical terms. The Learning Objectives clearly identify the knowledge and skills to be gained when the chapter is completed. The Technical Terms list the key words to be learned in the chapter. Definitions for the Technical Terms are given in the Glossary. Examples Illustrated Examples have been designed to clearly and simply communicate the specific topic. The Examples correlate the chapter content with graphic illustrations that include 2D orthographic views and 3D model views. Detailed explanations in the Exam- ples provide analysis of the content. Notes Notes clarify explanations in the text and provide more detailed information about related topics. End-of-Chapter Content Each chapter ends with a Chapter Review section containing content-related questions and problems that can be used for examination, review, or other purposes as defined by your course objectives. Each Chapter Review section contains the following ques- tion groups: Know and Understand, Analyze and Apply, and Critical Thinking. • Know and Understand. These questions enable you to demonstrate knowledge and comprehension of the chapter material. This section contains true/ false and multiple choice questions. • Analyze and Apply. These questions allow you to apply knowledge of the related content. This section contains short answer questions, calculation questions, and questions based on chapter illustrations. Copyright Goodheart-Willcox Co., Inc. 281 L E A R N I N G O B J E C T I V E S After studying this chapter, you will be able to: List and describe the geometric tolerances used to control orientation. Explain methods used to specify parallelism. Apply or interpret parallelism tolerances on drawings. Explain methods used to specify perpendicularity. Apply or interpret perpendicularity tolerances on drawings. Describe how to establish combination geometric tolerances and apply or interpret them on drawings. Explain methods used to specify angularity. Apply or interpret angularity tolerances on drawings. Identify and describe orientation tolerances specified at RFS, MMC, and zero geometric tolerance at MMC. T E C H N I C A L T E R M S angularity angularity tolerance multiple single-segment feature control frame orientation tolerances parallelism parallelism tolerance perpendicularity perpendicularity tolerance tangent plane Introduction Tto his chapter explains the concepts and techniques of dimensioning and tolerancing control the orientation of features. Orientation tolerances control the angular relationships of features to one another. Orientation tolerances are used to control par- allelism, perpendicularity, and angularity. When size tolerances provided in directly toleranced dimensions and coordinate tolerancing do not give necessary control for the functional design and interchangeability of a product, then form and profile toler- ances can be specified. Size limits control a degree of form and parallelism. Positional tolerances control a certain amount of orientation. Therefore, the need for further form and orientation control should be evaluated before specifying form and orientation tolerances. Orientation Tolerances When specifying orientation tolerances, the tolerance zone is related to one or more datums. A relation to more than one datum should be considered if required to stabi- lize the tolerance zone in more than one direction. Orientation Tolerances C H A P T E R 7 359 Copyright Goodheart-Willcox Co., Inc. Chapter Review Name ____________________________________________________________________ Know and Understand Answer the following questions using the information provided in this chapter. True/False _____ 1. True or False? A positional tolerance defines a zone in which the center, axis, or center plane of a feature of size can vary from true position. _____ 2. True or False? Basic dimensions are used with baseline or chain dimensioning systems to establish the true position from specified datums and between interrelated features. _____ 3. True or False? A positional tolerance is specified by a position geometric characteristic symbol, a tolerance, and appropriate datum feature references placed in a feature control frame. _____ 4. True or False? When positional tolerancing is used, the MMC or LMC material condition symbol must be specified after the positional tolerance if MMC or LMC is intended, and the MMB or LMB material boundary symbol must follow the specified datum feature reference if MMB or LMB is intended. Otherwise, RFS or RMB is the default. _____ 5. True or False? When locating holes using positional tolerancing, the location dimensions must be basic, and this can only be accomplished by placing a rectangle (box) around each of the basic dimensions. _____ 6. True or False? A positional tolerance at MMC means that the specified positional tolerance applies when the feature is manufactured at MMC. _____ 7. True or False? When a positional tolerance is specified at MMC, the axis of a hole must fall within a cylindrical tolerance zone located at true position and the diameter of this tolerance zone is equal to the specified positional tolerance when the hole is manufactured at MMC. _____ 8. True or False? When a positional tolerance is specified at MMC, the positional tolerance is allowed to increase equal to the amount of departure from MMC. The maximum amount of positional tolerance is applied when the feature is produced at LMC. _____ 9. True or False? When the axis of a hole is at the extreme side of the positional tolerance zone, this extreme side location is referred to as extreme positional variation. _____ 10. True or False? When the axis of a hole is at an extreme angle inside the positional tolerance zone, this extreme angle location is referred to as extreme location variation. _____ 11. True or False? Virtual condition is a boundary that takes into consideration the combined effect of feature size at MMC or LMC and geometric tolerance. _____ 12. True or False? The virtual condition is used to determine clearance between mating parts. _____ 13. True or False? The virtual condition of an internal feature is calculated by adding the related geometric tolerance to the MMC size of the feature. 450 Geometric Dimensioning and Tolerancing Copyright Goodheart-Willcox Co., Inc. Unilateral or Unequally Disposed Profile of a Surface The profile of a surface can also be specified as a unilateral or unequally disposed tol- erance using the same options available for the profile of a line previously described. The following options correlate with the drawing shown in Example 10-10. When a unilateral profi le tolerance is required, the unequally disposed profi le symbol is placed after the geometric tolerance in the feature control frame, as shown in Example 10-10A. When the unilateral profi le tolerance has material added to the feature or part, the profi le tolerance value is repeated after the unequally disposed profi le symbol. The feature control frame is connected to the edge view of the surface with a leader line. When the unilateral profi le tolerance has material removed from the feature or part, the profi le tolerance value is placed before the unequally disposed profi le symbol and a 0 is placed after the unequally disposed profi le symbol to show that the entire profi le tolerance applies to the side of true profi le that removes material from the feature or part. The feature control frame is connected to the edge view of the surface with a leader line. See Example 10-10B. When an unequally disposed profi le tolerance is required, the total profi le toler- ance value is placed before the unequally disposed profi le symbol in the feature con- trol frame and the value of the tolerance that adds material to the feature or part is placed after the unequally disposed profi le symbol. The feature control frame is con- nected to the edge view of the surface with a leader line, as shown in Example 10-10C. NOTE For convenience, Example 10-10 shows three methods of applying profi le tolerances. An actual drawing or model only shows one profi le tolerance application. B A C Goodheart-Willcox Publisher Example 10-10. Unilateral and unequally disposed profi le of a surface tolerance applications. A—Applying a unilateral profi le tolerance where the entire profi le tolerance provides additional material to the feature or part. B—Applying a unilateral profi le tolerance where the entire profi le tolerance has material removed from the feature or part. C—Applying an unequally disposed profi le tolerance. Chapter 7 Orientation Tolerances 289 Copyright Goodheart-Willcox Co., Inc. Model View Orthographic Views Meaning Goodheart-Willcox Publisher Example 7-7. Specifying parallelism of line elements relative to a datum plane. 364 Geometric Dimensioning and Tolerancing Copyright Goodheart-Willcox Co., Inc. Analyze and Apply Answer the following questions using the information provided in this chapter. 1. Describe the purpose of a positional tolerance. _____________________________________________________________________________ _____________________________________________________________________________ 2. Explain the types of control specifi ed by positional tolerances. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ 3. Identify the term that refers to the theoretically exact location of a feature of size. _____________________________________________________________________________ 4. A _______________ dimension is a dimension that is considered theoretically perfect. _____________________________________________________________________________ 5. Explain how a positional tolerance is specifi ed in a feature control frame. _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ _____________________________________________________________________________ 6. When locating features using positional tolerancing, basic dimensions can be drawn or indicated by specifying a general note. Give the general note used for this purpose. _____________________________________________________________________________ _____________________________________________________________________________ 7. Given the following drawing, a listing of possible produced sizes, and four optional feature control frames that can be applied to the diameter dimension, provide the positional tolerance at each possible produced size for each feature control frame application. Optional feature control frames A. B. C. D.