Establishment of Optimum Number of Scanning Points for a Scanning Feature Using Ultra Precision CMM

Coordinate Measuring Machine (CMM) is a measuring system with a movable probing system and capability to determine spatial coordinates on a work piece surface, that can be further analyzed to arrive at the required parameters. As geometry of feature is not ideal, the number of points, their distribution and their computation method have an effect on the results of dimension, form and position and therefore on also coordinate system. Discrete point probing uses only few points to calculate the ideal circle; the outcome of this is incorrect information on form shape. For features having functional requirement like assembly, running accuracy form is critical and true shape of the feature is required. Hence, CMMs are developed with scanning feature; which supplies the large data quantities for evaluation. The optimization of scanning parameters like number of points for a feature is one of the important parameters in the coordinate metrology. The aim of the paper is to describe the effect of number of points for scanning a feature and optimization of this scanning parameter and to adopt the optimized scanning data to the discrete point probing system.