Development of a three-dimensional vibrating tactile probe for miniature CMMs

This paper presents the development and characterisation of a vibrating tactile probe for miniature co-ordinate measuring machines. Current probing technology is limited by several factors including the reduced size of the parts to be measured, the use of novel and delicate materials for manufacturing and the need for lower uncertainties of measurement. The solution developed at the National Physical Laboratory (NPL) is a novel, silicon-free triskelion (three-legged) MEMS flexure structure assembled with a sphere-tipped micro-stylus. The mechanical design and modelling of the probe are reported along with a description of the manufacturing routes, assembly solutions developed, operation and metrological characterisation methods. Results from the experimental testing demonstrate that the probe is not affected by snap-in when probing in vertical and lateral directions. Preliminary results from experimental testing also demonstrate that the probe is capable of detecting the effect of the surface interaction forces within 150 nm of the physical surface, suggesting that the probe is capable of operating in a non-contact mode. The performance of the probe has been tested in both the vertical and lateral directions.