CIRP Encyclopedia of Production Engineering

2014 Edition
| Editors: The International Academy for Production Engineering, Luc Laperrière, Gunther Reinhart

Form Error

  • Albert A. Weckenmann
Reference work entry



The form error deviation of the real (manufactured) feature (i.e., line, axis, surface, center plane) from the geometrically ideal nominal feature measured and evaluated by analogy to the definition of the form tolerance in ISO 1101. It is the minimum distance of the quasi-parallel boundaries of a zone, in which the entire surface of a real feature, its line element, its axis, or its center plane remains. The boundaries of the zone are formed:

For standard features:

  • In 2D case by two geometrically ideal 2D features (lines), which are in a common plane

  • In 3D case by two – geometrically ideal – nominal features

The nominal 3D features or the nominal 2D lines must show everywhere the same distance to each other (Euclidian distance evaluated for the entire feature mathematically by Chebyshev criterion).

For profiles (freeform lines or sculptured surfaces):

  • For “profile any line” or “profile any...

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© CIRP 2014

Authors and Affiliations

  1. 1.Chair Quality Management and Manufacturing MetrologyUniversity Erlangen-NurembergErlangenGermany