b'Making the Grade ahighcobaltcontent,suchasfaced with exceptionally interrupted WPP30G or WKP30S, works best. cuts, end users should consider sin-The toughness is able to with- gle-sided negative inserts.which are usually 10-m-to-20-mstand the cracking tendency that isTheyprovide(a)robustand thick (0.0004" to 0.0008"), are moreintroduced by thermal shocking,high-precisionseatingsurface, effective for rough turning steelhe said. along with a wide-open chip groove than PVD coatings, which are lim- Garud said those grades for ther- and robust cutting edge, he said ited to about 10-m thick. mal shock are also suitable for inter- This combination tends to with-This translates directly to longerrupted turning, in which an insertstand the interrupted cuts very well.tool life, Bokram said. is hammered and punished. WhenDillaman said in addition to using In addition, a roughing insert tends to run at a moderate surface speed, which he said doesnt gen-erate enough heat to oxidize a PVD coating and activate its wear- and heat-resistant configurations.CVD coatings are already oxi-dized, Bokram said. They dontAT HOME INneedheattotransformtheirEVERY HABITAT.structures.To resist heat deformation whenHigh-performance turning at high cutting speeds, Garud said Walter USAs WPP05Smillinggrade has a coating with a highSignificant improvements in aluminum-oxide content and a Ti- productivity gerTec Silver coating.This grade allows speeds in ex-cess of 1,200 to 1,300 sfm (366 to 396 m/min.) in some steels, he said.For abrasion resistance, Garud said grades with hard and refined substrates, such as WPP10G with the latest TigerTec Gold coating,High-performance are suitable. For thermal shock re- holemakingsistance, a tough grade with a rel-atively large-grain substrate andGuaranteed process reliabilityctemag.comRegister for April 26s hour-long webinar based on this article.about the author Alan Richter is editor-at-large of CTE. Contact himwalter-tools.comat [email protected]/cteguide.com35Turning.indd 35 3/16/23 1:46 PM'