Tribological Potentials of PVD-Coated Mircotextures - TriPot

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In recent years, significant progress has been made in surface functionalization of forming tools for lubricant-free forming. In the completed SFB 747 "Micro Cold Forming" and in the recently completed SPP 1676 "Sustainable Production through Dry Processing in Forming Technology", the applicants' research groups worked intensively on dry forming using micro textured and PVD hard-coated forming tools. In the SFB 747 the focus was on cold forming of micro components (diameter ≤ 1 mm), while in the SPP 1676 the focus was on the tool development for lubricant-free massive forming of macro components. For both applications, it was possible to reduce friction and wear significantly by micro-texturing and subsequent PVD hard-coating of the tool surfaces. Additionally a significant increase of the quality of lubricant-free formed workpieces in terms of surface roughness and dimensional accuracy was achieved. The research in the SFB 747 and the SPP 1676 focused on technological solutions for the implementation of dry forming processes. A more fundamental description or modeling of the complex interactions of the micro-texture, the mechanical properties of the boundary layer below the surface and the PVD coating on the resulting tribology was not possible within these projects due to their more technological orientation. Several fundamental questions thus remained open. For example: What influence do the milling parameters have on the resulting microtopography and the resulting mechanical properties of the machined boundary layer and how do these properties affect the tribology? What influence have the various parameters of the microtexture and the material pairing on the resulting dry sliding friction and the run-in behavior? Up to which normal contact stress does the frictional force increase proportionally with the normal force, regardless of the macroscopic contact surface (Coulomb friction)? How do the properties of the microtexture and the coatings influence the four basic friction mechanisms adhesion, elastic hysteresis, plastic deformation and abrasion? How to design microtextures and PVD coatings to meet given triblogical requirements? Is it possible to predict the tribological properties of hypothetical microtextures using artificial neural networks? These questions are the subject of the research proposal presented here.