Basic investigations on boundary lubrication in metal forming processes by in situ observation of the real contact area
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In metal forming processes tribology plays a significant role for process feasibility and tool lifetime. Boundary and mixed lubrication conditions are predominant in metal forming processes. Hence the appearing real contact area which is mainly influenced by the topography of tool and workpiece has a major impact on friction conditions. For an improved understanding of friction at the interface between tool and workpiece, the flattening behavior of idealized asperities under boundary lubrication conditions is investigated by applying a translucent tool. Various liquid lubricants have been used. It has been revealed that the usage of certain lubricants leads to higher resistance of the asperity against flattening which would be in favor of reduced friction. Topography analysis and finite element simulations have been performed in order to get more insight into the mechanisms leading to this effect. The findings have been transferred to real topographies by micro upsetting tests with ground surfaces.
KeywordsProduction process Tribology Real contact area
The project is funded by the German Research Foundation (Deutsche Forschungsgemeinschaft DFG). This work was carried out within the framework of the EC Network of Excellence “Multi-Material Micro Manufacture: Technologies and Applications” (4M).
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