6533b85dfe1ef96bd12be656

RESEARCH PRODUCT

Surface and interface analysis of worn TiN (PVD) coated cold forging tools

subject

description

Abstract Wear of cold forging tools, improved by TiN (PVD) hard coating and used in the production of alternator and starter components in the car industry, has been studied in detail. The most complicated case was the tool that produced a clutch housing of high precision. The 630 kN press process (50 pcs min −1 ) caused heavy adhesive and abrasive wear due to material flow, high surface pressure and also wear in the direction of tool movement. Results show that on the worn functional surfaces of the analysed tool, the lifetime of which was extended with TiN coating by a factor of 8–10, the following features were observed: non-uniform TiN coating thickness decrease; long grooves, damaged areas, and zones opened to the ASP 30 steel substrate surface were found on the front functional surface; the forming edge (curve) was still completely covered with TiN coating and was undamaged; long grooves (channels) in the direction of tool movement and flaking-off areas were induced on the flank face. Oxidation products and carbon contamination were always detected on the worn surfaces. The surfaces, interfaces and wear features were studied by optical, scanning and transmission electron microscopy, by AES surface and depth profiling analysis and by the Talystep profilometry technique. The topography was also studied by the PtC replica method.