ENBIS: European Network for Business and Industrial Statistics

CMM measurement uncertainty and form error assessment

22 September 2009, 11:40 – 12:10

Abstract

Submitted by

Alistair Forbes

Authors

Alistair Forbes

Affiliation

Nationial Physical Laboratory, UK

Abstract

Coordinate measuring machines (CMMs) are important measurement systems in assessing critical quality characteristics in manufacturing engineering. Form error is one of the features assessed and is a measure of the departure of a manufactured artefact from its ideal shape, specified in terms of standard geometric elements such as planes, spheres, cylinders, etc., or CAD representations such as NURBS surfaces. The assessment of form error on the basis of measured coordinates will be influenced by the systematic and random effects associated with the CMM as well as the underlying geometry of the artefact being measured. Of particular importance are the parameter errors of the CMM that describe the non-ideal motion of the CMM probe as it moves within the working volume. In this paper, we describe how uncertainties associated with the parameter errors affect the accuracy of the assessment of form error.

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