Effects of Cutting Parameters on Tool Wear and Thrust Force in Drilling Nickel-Titanium (NiTi) Alloys Using Coated and Uncoated Carbide Tools

Abstract

The difficulties of machining nickel-titanium alloys are due to their high ductility and super-elasticity, strong strain-hardening, and excellent wear resistance. These characteristics lead to poor chip breakability, high cutting forces, rapid and aggressive tool-wear, as well as excessive burr formation during mechanical machining processes. The present study addresses these issues by evaluating the effects of drilling parameters and drill bit coatings on the growth of tool wear and development of the drilling thrust force. The findings from this research indicate that the TiAlN coated carbide drill was found to significantly improve the wear resistance of the cutting tool. Likewise, the results of thrust force development are consistent with the trends of tool wear growth for all of the tested carbide drills.

Investigation Of The Effects Of Machining Parameters On Tool Life And Surface Roughness During The Face Milling Of The NiTi Shape Memory Alloy With Uncoated Tools

“…It was determined that the surface roughness value increased as the feed rate of both cutting tools increased. These findings coincide with those in the literature [24,42,[70][71][72][73][74]. The decrease in surface roughness depending on the increase in the nose radius is an expected result theoretically (Equation 1) and increasing the nose radius to obtain lower surface roughness value is in line with the literature [38-45, 52-55, 70-72].…”

“…As we can see from the graph in Figure 4, the values of surface roughness are 0.530 μm at 20 m/min, 0.632 μm at 50 m/min, and 0.660 μm at 35 m/min from lowest to highest. It is known from the literature that with a higher cutting speed, the surface roughness of the workpiece can be reduced [70][71][72][73][74][75]. The reason for lower surface roughness at lower cutting speeds (less than 20 m/min) may be attributed to the BUE that is formed on the cutting tool, which increases the nose radius [38][39][40][41][42][43][44][45].…”

“…This is a consequence of flank wear ( Figure 5b) of cutting tool at high temperature because the friction coefficient increases with cutting speed [40][41][42][43][44][45][60][61][62][63][64][65]. An improvement in surface roughness due to the increase in cutting speeds is an expected result [65][66][67][68][69][70][71][72][73][74]. The increase in surface roughness at high cutting speed (50 m/min) and feed rate (0.14 mm/tooth) was attributed to the high tool wear on the cutting tool ( Figure 4c).…”

“…24% improvement (0.527 μm) was observed in surface roughness obtained at a high feed rate (0.14 mm/tooth) (0.691 μm) when the feed rate was decreased by 79% (0.03 mm/tooth). Increase in surface roughness depending on the increase in feed rate is theoretically (Equation 1) expected and the feed rate has to be reduced to decrease surface roughness [70][71][72][73][74][75]. A higher surface roughness value at high feed rate (0.14 mm/tooth) may be attributed to tool wear ( Figure 4c).…”

“…A decrease in surface roughness was observed when the cutting speed of 35 m/min was increased to 50 m/min. This may be attributed to easier deformation of the workpiece material and the formation of yield stress region as a result of increasing temperatures on the toolchip interface during cutting process [70][71][72][73][74]. 10% and 41% change was observed in surface roughness values when the feed rate was increased by 133% and 100% in the cutting process performed at 20 m/min cutting speed and 0.7 mm constant cutting depth.…”