Surface texture characterization of injection‐molded pigmented plastics

Abstract

Abstract An appropriate description of the surface textures deliberately created on injection‐molded plastic parts of interior car components is presented. A spatial wavelength‐dependent analysis is used as an interesting alternative to the traditional roughness parameters. Auto‐correlation functions and power spectral densities are examples of such spectral functions that include parameters both in amplitude and profile directions. Even fractal concepts can be useful descriptors. As an illustration, it is also shown how the effects on the surface topography of the plastic part of after‐etching the mold can be assessed by suitable descriptors. An experimental evaluation of injection‐molded plaques containing three different surface patterns was carried out using an optical profilometer, supplemented by contact stylus measurements. The ability to assess the topography of these plaques by means of a new fast photometric stereo‐technique, denoted OptiTopo, was also evaluated. In its present form, however, this technique does not provide a detailed description of the topography of a pigmented plastic. Reasons for this and possible improvements are discussed. Polym. Eng. Sci. 44:1615–1626, 2004. © 2004 Society of Plastics Engineers.