Approach for uncertainty analysis and error evaluation of four-axis co-ordinate measuring machines

In the present investigation, a new form of space frame for error evaluation and uncertainty analysis of four-axis co-ordinate measuring machines (CMMs) is proposed and applied. The novel space frame comprises a ball plate that incorporates seven high accuracy spheres. The volumetric error data obtained when a CMM measures the space frame, in different angular locations, can be used to verify whether a CMM maintains the manufacturer specifications. The experimental results have demonstrated that this space frame provides a practical and cost effective mechanical artifact to assessing the volumetric performance of four-axis CMMs. The developed technique can be applied for verification, periodic re-verification and acceptance test of any type of four-axis CMMs.