Module 2

TRAINING DURATION: 2 days (16 h).
PREREQUISITE: Module 1, or a very good knowledge of GD&T as per ASME Y14.5.

In a complete product definition, each function of the part must be described and controlled with GD&T specifications on the definition drawing. However, it is more often the case that the specification is incomplete because some functions are described/controlled imperfectly or not at all. There may be a good or bad correlation between the function and the set of GD&T specifications used.

The closeness of the correlation between the functions of a part and the GD&T specifications is the responsibility of the designer. Any lack of correlation could result in losses for the company. In Module 2, we present a systematic approach, inspired by world-class quality systems like APQP, using quality tools and specific engineering techniques to achieve complete random interchangeability of the components at assembly, taking into account the manufacturing and inspection constraints.


  • Review of key GD&T principles, like the selection of Datums, management of surfaces with profile, management of dimensional elements with position, modifiers, etc.
  • Functional analysis and quality tools.
  • The concepts of virtual zone of assembly and complete random interchangeability.
  • Tolerance chain analysis and tolerance distribution, conventional and statistical.
  • Managing fit and clearances between parts.
  • Selection and indication of Datums.
  • Calculating and applying position tolerances.
  • Calculating and applying profile tolerances.
  • Calculating and applying form tolerances

Module 2 is recommended to all personnel involved in detailing the product specification, at any level. Complex product specifications require a balanced design with considerations to constraints at all levels, requiring concurrent engineering. At the minimum, personnel from engineering, methods, manufacturing, and quality must be involved and would benefit from Module 2.