ANALYSIS AND PERFORMANCE OF A PARALLEL-AXIS FLATNESS MEASURING INSTRUMENT

摘要

This paper describes the design, analysis and performance of a flatness inspection instrument to measure workpieces with up to one millimeter departure from flatness. The instrument uses two air bearing spindles arranged with parallel axes to simultaneously rotate a workpiece and slowly pass a capacitance probe over the spinning surface. Capacitance probes offer user-selectable sensitivity to provide multiple combinations of measurement range and resolution. In tests with a high sensitivity probe, the instrument demonstrated measurement repeatability of 25 nanometers on a O75 mm workpiece. This paper presents a complete homogeneous transformation matrix analysis of the propagation of errors into the measurement as well as sample measurements on diamond-turned workpieces.