Interactive surface modelling, an implementation of an expert system for specification of surface roughness and topography

Abstract Making roughness a useful tool for obtaining optimally functional surfaces demands a high quality foundation for surface specifications. Erroneous specifications in many cases lead to costly production and perhaps nonfunctional surfaces. The Interactive Surface Modelling system, ISM, presented in this paper, addresses those problems with an approach where functional demands control the route from specification of parameters through manufacturing preparation to measurement of the machined surface. Here, the operator, be it the designer, the production engineer, or the quality control engineer, can interactively reason with the system to reach a suitable specification with the aid of integrated software in a PC-Windows environment controlled by an expert system software. The representation of the surface's 3D geometry then is a natural component. The access to depiction and literature references and standards is implemented together with the ability to serve the user with graphic feedback by generating synthetic surfaces from the specification made. The described features have been implemented in a prototype developed in cooperation between Volvo and Chalmers on two functional surfaces: cylinder liners and synthetic leather for the automotive industry. Problems with specifying correct roughness and topography actually have emerged when changes have been made of material or manufacturing process for an old and proven product. This has shown that knowledge is missing or incomplete about proper intervals for roughness parameter values for definition of the relationship between a surface's function and its parameters . The result is misunderstandings and errors. By letting ISM be a base for continuous updating and modification of knowledge, opportunities will be created for increased quality of surface roughness specifications through this systematic approach to the complex, expanding field of Surface Roughness and Surface Topography.