A new approach for the friction identification during machining through the use of finite element modeling

Finite Element Modeling (FEM) of chip formation has proved great sensitivity to tool/chip friction coefficient. This parameter cannot be adequately identified through conventional tests, because thermal and mechanical loadings during these tests are far from those encountered during machining. In this study, the inadequacy of using constant Coulomb's friction coefficient in FEM is showed. Although a good agreement is found for cutting force and chip thickness variables, significant differences can be found for feed force and tool–chip contact length. Differences of more than 50% are observed in some cases for those variables when FEM results are compared with experimental ones. A new approach to identify a friction model after experimental tests will be detailed. This new approach involves application of a variable friction coefficient at the tool–chip interface, which allows obtaining a better agreement between numerical results (differences close to 10%) regarding the feed force.