Finite Element Model to Calculate the Thermal Expansions of the Tool and the Workpiece in Dry Turning

Dry cutting is an important issue with regard to the economy and ecology of machining. The absence of the cutting fluid reduces both the costs for machining and the risk of ecological hazards. However, the missing convection through the cutting fluid increases the temperatures of the workpiece and the tool, and thus their thermal expansions. As a result, remarkable deviations from the nominal workpiece geometry occur. To enhance the accuracy of machining when dry turning, the thermal expansions of the tool and the workpiece can be calculated prior to actual turning using finite element (FE) models in order to adapt the nominal depth of cut accordingly. Therefore, an experimentally validated (using aluminum as the workpiece material) FE model is presented. The FE model inputs the heat flux into the tool and the workpiece as boundary conditions. The heat flux is applied locally and temporally discretized to the workpiece and the tool in the chip formation area. Their thermal expansions can thus be calculated in terms of the cutting condition used and the tool position, whereby process planning regarding the machining accuracy is facilitated.