CONCEPT FOR COMPUTER AIDED NON-CONTACT LASER ROUGHNESS EVALUATION OF ENGINEERING SURFACES

摘要

The importance of computer aided measurement techniques as a means of controlling industrial manufacturing and testing technical products with high accuracy increases ever more with the general goal of improving the quality of all kinds of products. This development started more than thirty years ago and is still improving. Especially computer aided roughness metrology is a very important and universal tool for solving measuring tasks in connection with workpiece accuracy, production quality, tribology aspects, quality assurance in industry, coating technology, electronic circuit production, assembly problems, statistical quality control and many other technical aspects. A method for non-contact profile assessment and roughness measurement of engineering surfaces is presented. The proposed system uses the well-known effect of focussing a light beam on the surface to be examined, at the same time compensating for the effect on the measuring results of varying material colors by appropriately processing the measuring signal. By combining a low-cost laser scanning unit with the traverse unit of a commercially available stylus instrument and a personnel computer for data processing, the prototype of an inexpensive system for non-contacting optical roughness measurement has been developed. Measurements performed on different specimens differing in surface properties, material and condition show a very high consistency of the evaluated roughness values and surface profiles gained especially in the case of precision machined surfaces.