Innovative gap measurement standard

A German research institute, active in metrology, has developed a new standard for precise measurements of gaps in threads and gearing, which is of enormous importance to ensure function and reliability. The gap measurement standard consists of a thermic, invariant base plate with at least four superimposed precision balls whose positions to each other are calibrated. In each case, two precision balls are forming one gap. The distances and diameters of precision balls and ball tips are so positioned that approximately the same geometric conditions exist, when e.g. measuring a thread or a gear. For metric threads the site conditions equal the profile angle of the thread of α = 60°. The calibration of the centre positions of the four precision balls is done on a coordinate measuring machine with integrated laser interferometer, based on the trilateration process. Ordinary calibrations in the area of coordinate metrology characterise the spatial probing behaviour of the stylus on the precondition of the probing process. Some measurement tasks are the area of thread and gearing measurements require a gap probing process in a double flank system, the so-called self- centering probing process. Here, significantly different correlations of forces lead to elastic deformations occur, which must be considered separately. For the determination of hereby resulting deviations in length measurements the so called gap standard has been developed. The research institute is searching for licensees.