Study of an Optical Measuring Method for Surface Roughness of Cast Metals

Abstract

The basic technology to measure rapidly the surface roughness of 3-dimensional cast metals using an optical non-contact method has been developed. In the experiment, the standard plates with surface roughness ranging from 100 μm to 400 μm for the evaluation of cast metal has been used. The standard plate is illuminated obliquely with the incident angle θi (=60°) and detected by CCD camera perpendicularly. An evaluated value F is calculated using the detected image. F is proportional to the surface roughness Ry when the standard plate is illuminated from both side at a right angle to inclined direction, and the plate is inclined with angles ranging from +25° to -25°. The surface roughness Ryis obtained by F with the error less than ±18% according to the proportional relationship between F and Ry.