MEASUREMENTS OF COATING THICKNESS OF DIAMOND-COATED TOOLS BY WHITE-LIGHT INTERFEROMETRY

摘要

In this study, the coating thickness of diamond-coated tools was evaluated and investigated by non-contact measurements. Commercial cobalt-cemented tungsten carbide (WC-Co) cutting inserts (edge radii from 5 to 80 microns) were used as substrates for varying CVD-diamond depositions. A white-light interferometer (WLI) was used to acquire the surface profile data around cutting edges. MATLAB algorithms were generated to further analyze the tool geometry using the data cloud obtained from the WLI.rnThe characteristics of a cutting edge (the edge radius, the rake/flank surfaces, and the wedge angle) were then obtained by curve fitting. This methodology was applied to both uncoated and coated tools for the geometry characterizations. To evaluate the coating thickness, the fitted uncoated and coated profiles (from the same tool) were overlapped with the edge rounding centers kept at the same location. The coated profile was then rotated to have the rake face parallel to the uncoated one (as a reference). The normal distance between the two tool profiles (uncoated vs. coated) was used for coating thickness estimates. The combination of WLI and the developed algorithm is capable of efficient coating thickness measurements. Tools with large edge radii had high uncertainties in coating thickness.