Experimental and Numerical Analysis for Safe Measurement Location on M544 CMM Working Table

A coordinate Measuring Machine (CMM) is a more flexible, adaptive, and precise dimensional measuring machine. Being a complicated measuring tool, CMMs can have a wide range of error sources that can lower measurement accuracy and increase measurement result uncertainty. Mapping and compensation techniques are commonly used to minimize measurement error in CMMs. However, the aforesaid techniques require resources and expertise. An alternate and less costly method of lowering CMM measurement error is to measure at its working table's smallest moving structural static deformation site. By looking at the CMM structure's stress and deformation using FEA, CMM measurement error can be reduced. In this paper, experimental and numerical analyses were used to determine the safe measurement site with minimum CMM measurement error on the CMM working table by analyzing the moving structural model. Based on the dispersed sample, the measurement plan was put into practice, and real measured samples were gathered using the Osmania University, Metrology Lab M544 CMM to validate the simulation. In addition, sensitivity analysis of the FEA simulation was conducted in relation to the key variables to confirm its robustness. The larger form error with the maximum measurement error was observed at the right end position of the ram and Z-shaft of the bridge type M544 CMM. The M544 CMM's right end (500, 0, 0) had a measurement error of 0.466 µmm due to the structural deflection, while the home position (0, 400, 0) had a measurement error of 0.146 µmm. The FEA static structural deformation result was in good agreement with the experiment. The safest place to take CMM measurements with the least measurement error is, at the middle 150 mm offset from the border of the rectangular granite-working table. This finding could support the manufacturing industry to reduce M544 CMMs’ measurement errors during inspection.