Application of Simulation Software to Coordinate Measurement Uncertainty Evaluations

Abstract: Uncertainty evaluations for coordinate measuring machine (CMM) metrology are problematic due to the number, ranges, interactions and generally unknown sensitivity coefficients of the parameters that can influence the measurement result. The situation is particularly difficult when a task-specific uncertainty is required and poses problems for both auditors and metrology practitioners. Auditors often lack satisfactory tools for a comprehensive assessment of a client's claims of traceability. Measurement professionals, similarly, have difficulty demonstrating compliance with measurement traceability requirements and, in addition, can find themselves at a real economic disadvantage if reliable measurement uncertainties are not known. In this paper, the historical perspective of, the motivations for, and the necessity of task-specific uncertainty evaluations are briefly discussed. This is followed by a presentation of the requirements and desirable features of a credible method for task-specific CMM uncertainty evaluation. Next, a description of the major design features of a practical software application for evaluating uncertainties of CMM measurements are presented. This is concluded by presenting several application examples and case studies which demonstrate that, in the arena of task-specific CMM uncertainty evaluation, simulation methods exhibit notable strength and versatility.