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Mechanical Engineering vocabulary · Tolerances and Measurement

GD&T

Meaning in mechanical engineering, with examples

/ˌdʒiː diː ən ˈtiː/abbreviationCommon term

In mechanical engineering, GD&T means: Short for geometric dimensioning and tolerancing: a system of drawing symbols that controls the form, orientation, location and runout of features relative to datums.

In Turkish: geometrik boyutlandırma ve toleranslandırma, geometrik toleranslar, form ve konum toleransları

How it is used

Used on drawings, in inspection and in supplier communication. It is defined by ASME Y14.5 in the US and by ISO GPS standards in Europe. Engineers read feature control frames for flatness, perpendicularity, position and runout.

Example sentences

  1. The customer drawing uses GD&T, so the hole positions are measured from datums A, B and C.

  2. Our new engineers need GD&T training before they review supplier drawings.

Common collocations

  • GD&T symbols
  • GD&T training
  • feature control frame
  • position tolerance
  • flatness tolerance
  • datumA theoretically exact point, line or surface on a part, marked with a letter on the drawing, from which other features are located and measured.
  • toleranceThe allowed amount of variation in a dimension or property, for example ±0.05 mm. A part is acceptable if its measured value falls inside this range.
  • technical drawingA precise drawing of a part or assembly that shows its shape, dimensions, tolerances, material and finish, so that it can be made and inspected.
  • inspectionChecking a part, product or machine against a drawing, specification or standard by looking at it, measuring it or testing it.
  • tolerance stack-upA calculation of how the tolerances of several parts add up in an assembly, to check that a gap, fit or position stays within its limits in the worst case or the typical case.

More terms: Tolerances and Measurement

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