Cobalt Steel Extremely Heat Resistant Twist Drill Bits with Straight Shank Set of 13pcs to Cut Through Hard Metals Such as Stainless Steel and Cast Iron

OverviewCOBALT STEEL - Manufactured from M35 cobalt steel, with molybdenum and cobalt added to creates a hardened alloy, measuring Rockwell hardness up to 67, extremely heat resistant; for much faster cutting and extra longer life span, with up to twelve times when compared with an average HSS drill bit. Will not "walk" or "wander". Straight shank allows for firmly holding and accurate centering, fit for standard drill chucks and regular round collet chucks. Must be used and operated at proper RPMs for maximum efficiency FOR METALWORKING - Particularly successful in cutting through hard metals such as stainless steel and cast iron, although they can be used for softer materials, too. Not for hardened steel / high carbon steel. Try to adjust the RPM when it fails to penetrate. DOWNLOADABLE USER GUIDE - We've summed up some tips of drilling metals, including a RPM chart for several common metals, based on our reviews and some articles on the internet.