| Popis: |
Articulated arm coordinate measuring machines (AACMM) have become popular because of their portability, flexibility, and reduced cost though it is generally reputed that they are less accurate compared to CNC CMMs. We have compared the performance of a CNC CMM with a touch-trigger probe to that of an AACMM for the measurement of inner diameter of bores. AACMM was used in three different methods, viz., manual triggering, probe scanning for two revolutions, and finally scanning for the same time as that for manual triggering. Using each method, 20 bores were measured twice in random order and the uncertainties were computed using the measurement systems analysis approach. It was found that the measurement with AACMM in scanning mode gave overall lower uncertainties in the measurement of diameter. This may be because even though the single point coordinate uncertainty is lower in a CNC CMM, a larger number of points can be captured at the same time with an AACMM in scanning mode, thereby resulting in a lower task-specific measurement uncertainty. |
