Study of Stylus Bending Effects on CMM Measurements and its Stylus Characterization

Coordinate Measuring Machines (CMMs) are widely used for a large range of precise measurement tasks. These tasks are expected to be carried out with increasing accuracy, speed and flexibility, as well as the ability to operate under shopfloor conditions. CMM Probe is the interface between coordinate measuring machine and work piece and it is responsible for the coordinate measurement accuracy. The CMM probe acts as a switch by stopping the movement of CMM and freezes the dimensional values os the contact between work piece and probe is made. One of the more prevalent kinds of CMM probes is the Touch Trigger Probe (TTP). TTPs work by sensing the impact of the stylus tip with the work piece. The aim of this study is to determine whether various probe head configurations and probing forces would have an effect on the CMM's ability to repeatedly measure a dimensional feature. During this study it was realized that probing force, stylus shaft length and stylus tip round ness ploys a crucial role in measurement. Relevant data from the study is presented.