Performance of coated, cemented carbide, mixed-ceramic and PCBN-H tools when turning W320 steel

TiN-coated cemented carbide, mixed ceramic and PCBN with a high percentage of CBN (PCBN-H) tools were used for reconditioned turning of hardened and tempered W320 steel hot working dies. The dies are usually scraped after their useful life because they are difficult to be reconditioned by machining. One alternative to scraping these dies is to convert them, increasing their internal diameters by internal turning. The machining experiments showed that coated carbide tools performed better at cutting speeds up to 120 m/min, while PCBN tools were superior at higher speeds up to 200 m/min. Mixed ceramic tools did not perform well under the conditions investigated. The tribological system showed abrasion, adhesion and plastic deformation as the dominant wear mechanisms. Chipping on the tool rake and flank faces, as well as catastrophic failure, was also observed in some experiments.