Burr Reduction in Drilling Titanium using Drills with Peripheral Slits

Abstract

Drilling of titanium alloy results in considerable burrs at the exit surface of a hole. The burrs deteriorate quality of hole surfaces and can cause misalignment during assembly. Therefore, burr minimization while drilling is necessary. In this study, innovative chamfered drills with slits have been developed to reduce the burr height and thrust forces. Dry drilling experiments were conducted using chamfered drills without slits and with slits (CWS) having four different point angles. Drilling performance was measured in terms of burr height, thrust forces, and chips morphology. A finite element method-based model was developed to simulate drilling of Ti6Al4V alloy using the drills without and with slits. The results show that the maximum burr height for CWS drills was reduced by 48.5% as compared to the conventional drills. The thrust forces were reduced by 5.5% and were in a fair agreement with the simulation results. For most of the cases, the simulated forces were within 10% of their experimental counterparts. Keywords Burr height Á Chip morphology Á Drilling Á Point angle Á Slit Á Thrust force Abbreviations CWOS Chamfered drill without slits CWS Chamfered drill with slits F t wos Thrust force with chamfered drill without slits F t ws Thrust force with chamfered drill with slits h wos Burr height with chamfered drill without slits h ws Burr height with chamfered drill with slits

Study of the burr height at hole exit in bone drilling by twist drills

“…By studying the functional relationship between the fitting factor and the response value of the multiple quadratic regression equation, the prediction model within the parameter range is determined. As shown in equation (2).…”

“…Many scholars have studied the burrs produced by the twist drill drilling process. Gajrani et al 2 used seamless and combined chamfer drills to drill titanium workpieces to study burr height, thrust, and chip shape. The results showed that the burr height generated during the drilling process of the slotted chamfered bit was 48.5% lower than that of the conventional bit, and the thrust was reduced by 5.5%.…”