A Uniform Concept for Calibration, Acceptance Test, and Periodic Inspection of Coordinate Measuring Machines Using Reference Objects

A method has been developed at PTB to carry out calibration, acceptance test and periodic inspection of coordinate measuring machines (CMM) using reference objects. The procedures are done by measuring 2-dimensional patterns in different optimally select positions with a multiple of probe stylii. The measured apparent deformations of the patterns are analysed to yield the corresponding information about the volumetric deviations of position of the inspected instrument. Unlike the conventional method of separately measuring machine errors this concept allows a direct traceablity of a CMM via one single pre-calibrated reference object. A full scope calibration can be performed with considerably less efforts for measurement and evaluation than it was required for so far used techniques but nevertheless with comparable accuracy.