This preview shows page 1. Sign up to view the full content.
Unformatted text preview: prove that a workpiece is compliant with the specifications, has to show that the measured characteristics are inside the conformance zone. Otherwise, a customer, who wants to reject a workpiece, has to prove that at least one characteristic is in the nonconformance zone. The standardized basis for this decision is defined in [ISO 14253-2, 1998] “Decision rules for proving conformance or non-conformance with specifications”. 3. DETERMINING MEASUREMENT UNCERTAINTY WITH CALIBRATED WORKPIECES To verify the capability of CMMs the feature specific measurement uncertainty has to be known and in an acceptable ratio to the tolerance of the workpiece. In coordinate metrology the main contributors to the uncertainty are CMM, workpiece, environment and operator including his/her measurement strategy [Weckenmann, 2001]. The experimental method described in [ISO 15530-3, 2000] is characterized by the summarization of all influences on the uncertainty and their superposition during the measurement. It is not necessary to know the separate influences. They are combined in the result of the experiment. Only systematic experiments allow identifying the actual impact of the variable influences. I...
View Full Document
- Spring '10
- The Land