Measurement of surface roughness by a machine vision system

A new method of surface roughness measurement was developed for use in a production environment. This method employs a microcomputer-based vision system to analyse the pattern of scattered light from the surface to derive a roughness parameter. The roughness parameters were obtained for a number of tool-steel samples which were ground to different roughnesses. A correlation curve was established by plotting the roughness parameters against the corresponding average surface roughness readings obtained from a stylus instrument. Similar correlation curves were produced for different materials such as brass and copper. Surface roughness measurement was also performed for specimens immersed in oil, a condition similar to that of a production environment. Some observable trends were found. The proposed method provides a fast and accurate means for measuring surface roughness. Its repeatability and versatility compares favourably with other methods.