Tribology in microforming

As the tribological conditions between tool and workpiece in metal working are of greatest importance for process feasibility and process quality this is even more true when the process is scaled from conventional down to micro dimensions. As can be shown by scaled friction tests the friction is increased by a factor of 20 and more which will have a distinct impact on all factors characterising the process. This cannot be described by the conventionally used friction laws but can be explained by the model of open and closed lubricant pockets characterising the surface topography. In the present paper, it will be shown that – starting from this model – the size effect in friction can be described by the general friction law developed by Wanheim/Bay.