Numerical Parameters for Characterisation of Topography

This chapter deals with the numerical parameters that form the basis of the new ISO standard proposal. Numerical parameters for surface texture as used in engineering drawings are the means of communication between design, manufacture and functional performance, and the means of communication between a supplier and a customer. These parameters are not only used as a benchmark for manufacture and surface tolerance specification, but also especially in the case of 3-D parameters to predict functional properties. Under the SURFSTAND project, the improvement and verification work was carried out with the emphasis on much stronger practical evidence and more feasible applications. As a result, an improved and updated set of numerical parameters was built up during the project. The new numerical parameter set for 3-D surface texture addresses the geometrical properties, namely field and feature characteristics. The field parameter set is used to classify indications of averages, deviations, extremes, spacing information, and generic functional properties. The feature extraction techniques are also a strong base describing summit/valley parameters and their mean size.