Mechanics of Titanium Machining

Titanium is widely used material in advanced industrial applications such as in aeronautics and power generation systems because of the distinguished properties such as high strength and corrosion resistance at elevated temperatures. On the other hand, the machinability of this material is poor. Relatively low thermal conductivity of Titanium contributes to rapid tool wear, and as a result, high amounts of consumable costs occur in production. Therefore, understanding the mechanics of titanium machining via mathematical modeling and using the models in process optimization are very important when machining Titanium both in macro and micro scales. In this chapter, mechanical effect of process parameters in five axis milling and micro milling are analyzed. Thus, different cutting conditions were tested in dry conditions and the effects of tool orientation on cutting forces in five axis macro milling was investigated. For five-axis ball end milling operation, a series of experiments with constant removal rate and different tool orientation (different lead and tilt angle) were conducted to investigate the effect of tool orientation on cutting forces. The aim of the tests was finding the optimum orientation of the cutter in which the normal cutting force applying on machined surface is minimum. Moreover, a new method to predict cutting forces for micro ball end mill is presented. The model is validated through sets of experiments for different engagement angles. The experiment and the simulation indicated that the tool orientation has a critical effect on the resultant cutting force and the component that is normal to the machined surface. It also possible to predict the tool orientation in which the cutting torque and dissipated energy is minimum. In micro milling case, the force model for ball end mill is able to estimate the cutting forces for different cutting conditions with an acceptable accuracy.

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