TABLE OF CONTENTS Mark A.Nasson
Draper Laboratory
Cambridge, Massachusetts
Mr. Nasson is a principal staff engineer at Draper Laboratory and has twenty years of experience in precision metrology, dimensioning and tolerancing, and quality management. Since 1989, he has been a member of various ASME subcommittees pertaining to dimensioning, tolerancing, and metrology, and presently serves as chairman of the ASME Y14.5.1 subcommittee on mathematical definition of dimensioning and tolerancing principles. Mr. Nasson is also a member of the US Technical Advisory Group (TAG) to ISO Technical Committee (TC) 213 on Geometric Product Specification. Mr. Nasson is an ASQ certified quality manager.
This chapter describes a relatively new item on the dimensioning and tolerancing standards scene: mathematically based definitions of geometric tolerances. You will learn how and why such definitions came to be, how to apply them, what they have accomplished for us, and where these definitions may take us in the not-too-distant future.
After reading this chapter, I hope and trust that you will be asking the reverse question: Why not mathematical definitions of tolerances? As you will see, a number of interesting events combined to open the door for their creation. In short, though, mechanical tolerancing is a much more complex discipline than most people realize, and it requires a similar level of treatment as has proven to be necessary for the nominal geometric design discipline (CAD/solid modeling).
Although the seeds for mathematical tolerance definitions were planted well before the early 1980s, a special...
