Surface Modifications for Optimized Forming Operations

Abstract

During forming operations the contact conditions relating to the surface of the tools, the intermediate coolant or lubricant and the hot work piece material are determining the material flow and the resulting wear. The possibilities for an optimization of the tool surfaces are aspects of various scientific activities of IST and IFUM and are subject of this paper. Tools typically made of hot working steel can be treated with different technologies in order to achieve wear resistant properties. First of all, the surface is mainly determined by its topography which is defined by the manufacturing method or applied finishing technology. This paper will give an overview to adjustable surface properties with additional conditioning methods like severe shot peening. The stabilization of the topography is a new approach to enhance the wear resistance of forming tools. Several models like the Abbott-Firestone graph are used in order to obtain suitable describing parameters such as the roughness-parameter sk. The development of sk during the running-in stage has a strong influence on the tool life which can be shown. A stabilization of the topographical conditions can enhance the service life of the tools. It will be shown, that this is possible by applying plasma diffusion treatments and thin film coatings by means of vacuum coating technologies.