Characterization of grinding wheel topography using a white chromatic sensor

Abstract

This paper introduces a non-contact, non-destructive three-dimensional wheel scanning system which is capable of measuring and characterizing the surface topography of grinding wheels. The scanning system employs a white light chromatic sensor that traverses across the wheel surface using motorized stages controlled by a computer. With a planer resolution of 2μm and a depth resolution of 25nm, the novel scanning system was shown to compare well with a HITACHI S-4700 Scanning Electronic Microscope and a Nanovea PS50 profiler for measuring a 60 grit aluminum oxide grinding wheel—without having to destroy the grinding wheel to take the measurements. It was shown that image processing techniques, including segmentation and “blob” analyses, were able to extract the cutting edge density, width, spacing and protrusion height from the raw topography measurements. The wheel scanning system was then used to characterize the surface of a grinding wheel that had been dressed using fine, medium and coarse dressing conditions. The resulting cutting edge width and spacing was found to be exponentially distributed over the wheel surface—regardless of the dressing condition, while the cutting edge protrusion height appeared to be approximately normally distributed. The coarse dressing condition yielded fewer, smaller and more widely spaced cutting edges than the medium and fine cases. Furthermore, for the dressing conditions used in this research, it was observed that dressing noticeably affected the grinding wheel surface to a depth of 80μm, while grain geometry and spacing dominated the surface topography beyond this depth.