Different Approaches in Uncertainty Evaluation for Measurement of Complex Surfaces Using Coordinate Measuring Machine

TLDR

The study aims to develop a methodology for assessing the uncertainty of Coordinate Measuring Machine measurements on complex real workpieces and to guide future research toward simulation-based approaches. The methodology employs two scanning‑mode approaches—(1) estimating uncertainty via basic geometric primitives and (2) treating the complex surface as an unknown—guided by a Taguchi design varying scanning speed, sample density, probe configuration, scanning direction, and object position, and incorporates machine specifications and temperature effects for Type B uncertainty. The uncertainty analysis yielded Type A uncertainties between 0.65 μm and 6.47 μm, while the Type B component was approximately 0.4 μm.

Abstract

Abstract This paper describes a methodology for uncertainty assessment for Coordinate Measuring Machine measurement of complex real work pieces from industry. The study applied two approaches (in scanning mode only) for estimating the measurement uncertainty with the support of Taguchi plan in the experiment containing five factors: scanning speed, sample density, probe configuration, scanning direction, and position of measuring object. In the first approach the uncertainty was estimated by measuring the basic geometric objects (primitives like sphere and torus) representing the decomposition of complex surfaces and in the second one a complex surface was treated as an unknown quantity. Calculated uncertainty Type A for both measurement tasks was in the range from 0.65 μm to 6.47 μm. Evaluation of the uncertainty Type B covered specifications of the machine and standard uncertainties derived from temperature effects. Total u B component was found to be in order of 0.4 μm. Future research will be directed towards the development and application of simulation methods