Evaluation of Measurement on Small Arc Features using CMM

Abstract: Due to the fast development of the tooling solutions technology, the manufacturing accuracy of inserts from Sandvik Coromant AB, Gimo, Sweden have been tremendously improved and they are hence focusing on enhancing the measuring accuracy of small arc features on inserts, because the measuring accuracy and method of the current CMM in the factory may not satisfy the requirement of tiny features. This report aims to investigate the relation between the measurement uncertainty and the radius as well as angle of arcs, through experiments, in order to observe the achievable specification limits with different radii and angles.The research objects are four carbide-cemented gauges with different radius, which are divided into four groups. Every gauge is scanned circularly by a CMM and the point coordinates are recorded before the coordinates are further processed by an Excel macro to acquire the results with different angles. After each experiment is repeated ten times, all data are integrated and analyzed. The specification limits under different combinations of radii and angles are calculated and treatedas the ‘best case scenario’ for future researches. Additionally, the analys is also indicates that the measurement uncertainty is not strongly related with the arc radius, instead, it is obviously affected by the angle of the accessible arc. It is also revealed in the last chapter of this report that limitations still exist in this research and the future suggestion has also been proposed.