Analysis of profile measurement techniques employed to surfaces planed by an active machining system

The importance of a reliable and robust surface profile measurement system in the inspection of surface finish is beyond any doubt. For years, visual inspection has been employed in industries to determine the quality of surface finish. Since, in most cases, it fails to ensure a consistent minimum standard of finish quality, mechanical stylus based measurement systems have successfully taken over from human inspection. However, in recent years, the trend is to explore other techniques for conducting surface profile measurements. Non-contact optical methods have emerged as one of the leading candidates. In this paper, capabilities of two optical profile measurement methods (namely, light-sectioning and two-image photometric stereo) have been explored for surfaces machined using an active machining system. These profile measurement results have been compared to the ones obtained from a conventional mechanical stylus instrument. An industry-standard Talysurf CLI system has been used to provide the benchmark, traceable to NPL standards, for the measurements. Suitability of different measurement techniques have been discussed based on the results obtained.