Performance of coated carbide tools for high speed machining of hardened steel under high pressure coolant condition

Abstract

A dillieull-to-eut material like hardened ~tccl i~ used predominantly in the automotive and !>caring industries due t,) its exceptional ~-orrosi"n ami thcrmal re~istanee and high shear strength. Ahnls;ve maLhining processes such as grinding have lypically heen required to machine hardened steels, hut advances in machine tools and cutting materials have allowed hard turning '.m modern lathes to become a realistic replacement for many grinding applications. De:;pite so many advantages, implementation of hard turning remains relatively low, primarily due tn concerns about the quality of hard turned surfaces and a lack of understanding about the wear behavior of cutling took In general, the most important point in machining proccsses is the productivity, achieved by cutting the highest amount of material in the shortest possible time using t()l)ls with the longest lifetime. Combining all the parameters involved in the machining process to maximize productivity is, nevertheless, a very complex ta~k and becomes much more difficult when working at high speed machining in hardened steels. To address thi~ concern, this research investigated the ellcet:; of cbanging pmcess conditions on wear behavior when turning harden~-dmedium carbon steel (56 HRC') with coaLedcarbide cutting tools. The aim of this resean:h is to investigate the influence of fccd rate and cutting speed on the wear behavior of both ShlMG and SNMM coated carbide inserts under high pressure coolant condition. Invc>;tigation on the effC(;t of high pressure coolant on the machined chip, culling tcmpcmturc, cutting force~ alld product quality is the prime intention of this rcsC'<lfCh. XlII To become a realistic replac,'ment for grincing operation, surface roughness produced by hard turning must be eomr<lL:~bleto grinding process if hard turned surfaces are to be accepted, Steady and prugressive sUlfaee oollghnesses with dimensional deviation have been investigaled in this research wInk. The rcsulls indiCllte that proper 'electi,," of machining condilion and high PI\'SSUI\' cooling system yields acceptahle dimensional accu,dCY and surface quality. It also allows adequate tool life by keeping the cutting zone temperature and cutting forces at lower ievels.