Performance analysis of cryoprocessed conventional HSS M2 drill and P/M HSS M3 TiN coated tap and its effect on the substructure

Abstract

The experimental study investigates the performance of cryogenically treated conventional uncoated H.S.S. M2 Drills and P/M H.S.S. M3 TiN coated taps. The fermentation factors and their assigned values maintained constant throughout the study were soaking temperature of −185 °C, soaking time of 16 h, cooling rate 1 °C/min to 2.5 °C/min followed by soft tempering at temperature 100 °C and soft tempering time of 1 h. For conventional uncoated H.S.S. M2 drills, the speed and feed rate were offset by 10% on lower side and higher side of the datum. For P/M H.S.S. M3 TiN coated taps, the speed and feed rate were offset by 5 % in the steps of three on the higher side of datum. It has been observed that tool life of conventional uncoated H.S.S. M2 Drills is improved by 100% or twice with 10 % increase in speed and by 80 % or 1.6 times with 10 % increase in feed rate. The tool life of P/M H.S.S. M3 TiN coated taps increased by 175 % or 3.44 times with 10 % increase in speed and feed rate as compared to the datum parameters. TiN coated taps shows maximum tool life without any damages or dislodgement to the coated surface. Therefore the adherence of coating is found to be strong without any interfacial imperfection between the matrix and the coating. The increased tool life of such coated tools can be attributed to decreased surface roughness values. The improved performance of the drills can be attributed to refinement in carbides which increases wear resistance during cutting.