Transformation and thickening of chip during high throughput drilling

Abstract

One of the major difference in drilling process when related to other conventional metal removal processes like turning and milling is that the drill tool has to work beneath harsh environment as the metal cutting region is situated deep inside the work material. Also, the chip flow is restricted only through the flutes, and hence there occurs transformation of chip shape, chip thickening, and changes in force and torque. In the present investigation, high throughput drilling has been performed under a dry and wet environment in an intermetallic titanium aluminide which is an exceptional class of material with superior properties. It is found that the chip shape transformed from spiral to folded ribbon as the depth of hole increased. Also, a substantial increase in chip thickness, thrust, and torque was observed, and toward the end of drilling, chip clogging occurred. An analytical model was established by applying the mechanics of oblique cutting to find the torque and thrust by measuring the thickness of chip, and this model was validated experimentally.