FORM ERROR MEASUREMENT BY COMPARISON WITH A REFERENCE OBJECT

Traditionally, form error measuring machines compares the form of the object with a precise linear or rotary motion generated by a precision bearing. As an alternative strategy, this paper presents a strategy based on the comparison of the object form with the form of a second object. This makes the measurement accuracy independent of the motion accuracy of the measuring machine, opening possibilities for keeping conventional measurement accuracy but using bearings of lower accuracy – this means measuring machines of lower cost. A roundness measuring system based on this new strategy is presented. Even using a ball-bearing with non-repetitive motion errors larger than 2µm, the presented system, shows a final measurement repeatability better than 0.3µm, proving the effectiveness of the proposed strategy