Quantitative evaluation of the surface finish of high gloss polished tool steels

Abstract

Standardized procedures to measure and estimate surface qualities of moulds for injection moulding of plastic components do not exist. Instead, steel producers as well as polishers and mould-users need to rely on master plaques for tactile comparisons and/or their own visual estimations for surface quality controls. This paper presents an overview of various surface evaluation methods of steels, including existing standards and available surface metrology. A new method to evaluate high gloss polished tool steel surfaces, based on a three-dimensional non-contacting measurement technique, is presented. The suggested method is based on defect extraction, and should be useful for both specifications and quality controls. Included defects were found to be quality criteria for polished tool steel surfaces. The surface acceptance levels and defect classification are based on interviews and questionnaires, as well as literature studies and visual estimations of test samples made by experienced polishers.