Surface roughness and measurement with new contact methods

To obtain high-quality products requires, among others, testing of material properties and measurements of dimensions and errors of surface geometry. The development of surface roughness evaluation depends on the introduction of cheap and easily-applied measuring instruments. The most commonly used stylus-type devices are of complicated construction, expensive and require highly qualified quality control personnel or workers to operate. On the other hand, optical and pneumatic methods are, due to their sensitivity to disturbances and large measuring errors, by far less commonly used. Investigations are conducted in the Institute of Mechanical Technology at the Technical University of Warsaw on the development of methods to construct simple devices designed for measuring the surface roughness directly on the work-stand. Until now two contact methods have been developed with measuring elements movement restricted to the orthogonal direction in relation to the surface measured. The first one is an indirect method using the effect of interpenetration of rough surfaces and enables very simple measuring devices to be constructed, their measuring error reaching up to 20 per cent. The other one is a direct method of roughness levelling depth (R_p) measurement and enables measuring devices of much higher accuracy to be built.