Self-lubricating HPPMS-CrAlN-coatings for the use in dry cold forging processes of steel

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Forming manufacturing processes of cold forging are of great importance due to the high material utilization and the associated energy and resource efficiency in the production technology. In order to make cold forging processes controllable, liquid and solid lubricants are used, which are often questionable due to ecological, economic and legislative reasons. For this reasons, dry forming exhibits an increased research potential. Abdication of lubricants for dry tribological systems in forming leads to an increase of requirements. These requirements are controlled by suitable surface structures in combination with a self-lubricating coating.The description of the tribological properties using structured workpiece surfaces in combination with a self-lubricating coating based on the current state of the art are insufficiently explored. Therefore, the challenge is to explore a combination of friction-reducing surface structures on the workpieces and a wear resistant, self-lubricating coating on tools, which allows dry forming in cold forging for the first time.The aim of this project is the generation of a model in order to explain the tribological interaction between the workpiece topography and a self-lubricating coating. The aspired model should explain the physical, thermal and chemical mechanisms of dry forming of mild steel materials by empirical relationships and analytical formulations, which involve friction and wear. In a first step, the preparation and characterization of a novel self-lubricating coating using HPPMS (High Power Pulsed Magnetron Sputtering) process will be carried out. A further research focus is the development of a friction-reducing stochastic surface structure in order to reduce the true contact area. In a subsequent composition, the interaction between the newly developed HPPMS coating and structured workpiece surface will be studied. The persecuted hypothesis is, that it exists a tribological system, which is characterized by a special tool coating system in combination with a defined workpiece structure, so that friction and wear are reduced. Dry forming is then reliably and economically feasible.