The role of geometric dimensioning & tolerancing (GD&T) and how to capitalise on its value proposition


Executive summary

This whitepaper describes the engineering standards and benefits of Geometric Dimensioning and Tolerancing (GD&T), along with the supported attributes in the PC-DMIS measurement software.

Section 1: Benefits of GD&T

‘Benefits of GD&T’ discusses how manufacturing processes benefit from GD&T:

  • Geometric tolerances vs. plus and minus tolerances
  • Datum features with modifiers providing additional tolerance
  • GD&T as an international language that provides concise specifications, with one interpretation that ensures correlation with suppliers globally and parts that meet functional requirements.

Section 2: Differences between ASME and ISO

‘Differences between ASME and ISO’ explains the different GD&T standards and shows examples of where terms are different but have the same definition (features of size) and examples of the same geometric tolerance but different definitions (profile):

  • Features of size – ASME Y14.5 compared to ISO 14405-1: 2010
  • Profile tolerance – ASME Y14.5 compared to ISO 1101 (2004 and 2012)

Section 3: GD&T standards supported by PC-DMIS

‘GD&T Standards Supported by PC-DMIS’ shows examples of GD&T attributes for:

  • Features of Size
  • Material Condition Modifiers
  • Calculating and applying Datum Shift
  • Simultaneous requirements for Position and Profile tolerances
  • Calculating and report actual values for Profile.