Surface characteristics and machining performance of TiAlN-, TiN- and AlCrN-coated tungsten carbide drills

Abstract

This article presents a comprehensive analysis of surface characteristics and drilling performance of uncoated and coated tungsten carbide drills. The single- and double-layer coatings of TiN, TiAlN and AlCrN were examined in terms of surface roughness, microhardness and crack resistance. In addition, drilling torque and thrust force were experimentally measured and compared to the developed models based on the drilling mechanics and drill geometries. Tool wear and hole surface roughness were also considered to assess the machining performance of different coated tools. The results revealed that all coated drills can offer better cut surface quality, 28% lower cutting loads and longer tool life than the uncoated drills. Although AlCrN was found to be the hardest coating material among the others, it caused large wear on the cutting edges and poor surface roughness of produced holes. The lowest torque and thrust force were achievable using TiN-coated drill, while the use of TiAlN coating resulted in the lowest surface roughness and smallest tool wear. Furthermore, the drilling torque and thrust force model developed in this study were found to correspond to the experimental measures with the average error of 8.4%. The findings of this work could facilitate the selection of coating materials to advance the machining performance.

The effect of cutting tool coating on the form and dimensional errors of machined holes in GLARE® fibre metal laminates

“…Similarly, the thrust force recorded using TiAlN drills was between 49.26 and 62.27% higher than that recorded using AlTiN/TiAlN tools. A previous study also reported that the cutting forces generated using TiN-coated drills were lower than those generated by TiAlN-coated drills [52]. It could be speculated that the AlTiN/TiAlN coating provided a better self-lubricating effect due to its multilayer coating structure, but this needs to be confirmed in a future study.…”

Multi-spindle drilling of Al2024 alloy and the effect of TiAlN and TiSiN-coated carbide drills for productivity improvement

“…According to Bouzakis et al [31], the good performance of TiAlN than TiSiN was due to the weaker adhesion properties of TiSiN, despite the increased strength. Also, as discussed earlier, the co-efficient of friction of TiSiN is more than TiAlN [21], which increased the tool wear by increasing the tendency of sticking the materials from the workpiece on the tools [15]. Besides, the reason for the high BUE of the coated drills than the uncoated drill bits might be due to the low drilling parameters selected in this study.…”

“…Besides, the coefficient of friction of TiSiN is greater than that of TiAlN coated tools [21], and according to Prengel et al [37], the low coefficient of friction reduces the BUE. Hence, smaller values can be expected due to the lower cutting loads and less tool wear as a result of coatings' low friction coefficient [15]. Therefore, multi-spindle drilling increases productivity by drilling more than one hole and using uncoated drills would save manufacturing costs.…”

“…In another study by Wang et al [14], the life of TiSiN tools was found longer than TiAlN when high-speed machining experiments were performed to analyse the wear and breakage of the tools. Dumkum et al [15] reported that the TiAlN gave the lowest surface roughness and smallest tool wear while TiN-coated drills resulted in the lowest thrust force and torque. Kurt et al [16] recommended using HSS-Co 5%, during dry drilling of Al2024 for minimal hole diameter deviations compared with an uncoated, TiN and TiAlN coated drills.…”

Influence of rotational speed on mechanical features of thermally drilled holes in dual-phase steel

“…In conventional drilling process, large amount of chips were generated from the workpiece, which get adhered with the tool as well as the workpiece and then damage the surface quality of a finished hole. [1][2][3][4] The reliability of joint strength depends on the characteristics such as efficient screw thread strength and clamping heavy loads which are not obtained through this way of conventional procedure. Besides, fastening of sheet metals or thin-walled structures via conventional drilling method requires threaded inserts or welded nuts.…”