Analysis of geometrical errors in measurement data of ultraprecise-turned standards for roughness measurements

摘要

At the Physikalisch-Technische Bundesanstalt (PTB), ultraprecision machining has been used for the production of standards needed for the calibration of tactile and non-contact measuring instruments for more than two decades. At the physical limits of manufacturing and measuring capabilities, it is sometimes difficult to find the source of an evident geometrical aberration in a measurement result because the sum of the errors of manufacturing and measurement is considered. In this study, the measurement results of a stylus instrument on a diamond turned roughness standard are discussed. Computer generated profiles, which are used for trajectories for ultraprecise turning, are corrected and then compared to the measurement data of a nickel-phosphorus-plated surface. The modelling of the geometrical errors with a morphological operator is a sensible analysis tool. In this study, submicron geometrical errors of the tool are detected in the profile measured by the stylus instrument. Various results are shown to visualize the difficulties in separating the corresponding geometrical errors in the nanometre range. In particular, lateral distortion must be taken into account.