Modern types of PVD/PACVD coatings used for injection molds and their effects on selected physical properties of mold cavities

Abstract

This research paper deals with an effect of injection mold core/cavity surface and their additional treatment on selected optical properties and surface quality of these tool parts. Used mold cavities were made from tool steels 1.2343 (chromium-molybdenum-vanadium-silicon steel with good hardenability) and 1.2083 (martensitic steel with high chromium content), their surface was polished to the roughness of Ra = 0.08 microns (manufacturer guaranteed mirror finish). For purposes of an experiment, injection mold with interchangeable core/cavities was designed and manufactured. Subsequently, simple shape cavities were manufactured (plates with dimensions of 120 × 120 mm) and further were provided with a specific coating in order to change surface properties. In total, three types coatings were applied; CrN, AlTiN and hydrogenated a-C:H coatings. All cavities were measured using 3D non-contact roughness tester in different areas in cavity (totally 8 areas per cavity were selected in various distances from polymer inlet). Specifically, surface gloss under different reflection angles with respect to coating or tool steel type was evaluated from optical properties. The results show that the additional surface treatment of injection mold cavity with coatings can reduce the values of roughness parameters, however, affect the level of core/cavity gloss. © 2017 TANGER Ltd., Ostrava.