Superhard Drills
Revision as of 02:56, 24 December 2006 by 62.253.32.4 (talk)
Presented in order of increasing hardness:
HSS Standard drill bits are HSS.
Titanium Nitride or TiN. A gold coloured coating applied to HSS bits. (Not sure if this is the correct position for TiN coated drills on the list) Good for drilling aluminium, which sticks to HSS.
Cobalt drill bits. These can be used for drilling out broken HSS drill bits. They are also used for drilling stainless steel, but stainless is liable to blunt them.
C 1150 with short flutes and long shank.
D 200 twist drills look like ordinary HSS drills, but are hard enough for reliable service with stainless steel.
Solid tungsten carbide drill. Hard enough to drill through screw extractors.
Diamond drills are the hardest of all.