A novel method for measurements of surface topography in previously inaccessible areas

Since mechanical properties of parts in mechanical engineering are influenced in many ways by their surface structure, detailed knowledge of the surface structure is essential for predicting and describing these properties. Tactile and optical measurement methods are well established but cannot always reach every area of a part due to geometric constraints. To enable measurements in these areas, a method utilizing impressions and a laser scanning microscope is proposed. It is easy to use and able to correctly reproduce surface structures of technical surfaces, which is proven by a comparison of original parts and impressions of three surface areas on an example specimen. Two application examples from the domain of fatigue strength tests are shown. The surface structure is measured directly in the notch radius of shaft shoulders and inside hollow shafts made in different manufacturing processes. Utilizing modern optical measurement instruments, the proposed method enables accurate measurements of surface structure in previously inaccessible areas.