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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

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An appropriate selection of the laser parameters is critical in realizing the potential of laser-assisted machining (LAM) for hard-to-cut materials. This work presents a 3D FEM-based model of laser heating in laser-assisted machining of Ti6Al4V to select the laser parameters. The model accounts for the effect of the laser-tool gap, laser scanning speed, laser power, and laser path (linear and sinusoidal). The laser heating is modeled using a moving continuous heat source with a Gaussian intensity distribution, implemented in Abaqus/explicitTM with the help of a VDFLUX subroutine. The results suggest that the laser-tool gap plays a significant role in heating the entire cutting region. Regardless of power and scanning speed, the laser-tool gap must be sufficient to allow heating of the cutting region. The laser power should be sufficient to soften the material in the cutting zone, but it can be minimized by choosing an optimal value of the laser-tool gap. Also, sinusoidal laser scanning produced the desired thermal softening effects at lower laser powers than linear laser scanning. Accordingly, similar cutting forces are observed in LAM with sinusoidal laser scanning at only half of the laser power as that of linear laser scanning. However, due to the fluctuations in the cutting force for sinusoidal laser scanning, it can be recommended only for rough cuts in machining. The study demonstrates that through an appropriate selection of the laser parameters, the entire cutting zone can be heated to temperatures between 300-500 oC, desired in the machining of Ti6Al4V.