Investigation of the effect of cryogenic process applied on cutting tools on drillability of the DIN 1.2738 mold steel

In this study, for the drilling of the DIN 1.2738 mold steels, the effect of cutting parameters and of the cryogenic process applied to the cutting tools on cutting forces, moment, surface roughness and tool wear were investigated. As the cutting tool, uncoated and TiAlN coated HSS and tungsten carbide drills were used. Cryogenic process was applied to some cutting tools at -145 ºC waiting 24 hours. In drilling experiments as cutting parameters four different cutting speeds (for HSS tools 20 m/min, 22 m / min, 24 m/min, 26 m/min and for carbide tools 50 m/min, 55 m/min, 60 m/min, 65 m/min) and three different feed rates values (0,06 mm/rev, 0,08 mm/rev and 0,1 mm/rev) were used. On a CNC vertical machining center through holes of 24 mm depth were drilled with 8 mm diameter drills. As a result of the experiments, it was determined that the cryogenic process had a significant effect on improving of the machining performances of the uncoated HSS, TiAlN coated HSS and tungsten carbide tools. As a result of the wear experiments, it was seen that the cryogenic process caused 15% performance increase on the TiAlN coated HSS tools, 98% performance increase on the uncoated HSS tools and 115% performance increase on tungsten carbide tools. When taking into consideration the effects on the machining outputs, the effects of cryogenic treatment were more effective on tungsten carbide tools than the other tools.