Why filtering surface profiles

Abstract This position paper is to discuss the problems of assessing microgeometrical deviations at surfaces of geometrically defined bodies. The new ISO 4287:1996 defines a lot of parameters for the 2D-assessment of three different types of profiles, the primary profile, the roughness profile and the waviness profile. Concerning the microtopography, the standardized procedures of electrical filtering for separating roughness and waviness are a convention which was derived from the possibilities of the computer-aided evaluation of profiles, which does not necessarily refer to process and functional properties. To reduce the again proliferated number of parameters by the edition of the above-mentioned standard, it is proposed to omit the electrical filtering and to evaluate the primary profile with its superimposed roughness and waviness within the evaluation length lp only. In this case, lp is used as sampling length filter. The practicability and usefulness of this proposal are discussed, also regarding the increasing 3D-evaluation of surfaces to be expected. Concerning the amplitude parameters to be used for assessing, tolerancing and process supervising, the application of parameters based on a statistical consideration of the amplitude density curve is recommended.