Sorry folks, I lost my mind. What I was talking about was surface treatment not case hardening.
"Black Oxide surface treatmant-improves chip flow and increases abrasion resistance by increasing the ability of the drill to retain lubricants. Also provides additional tempering and stress relief to the drill."
"Titanium Nitride coating- Acts as a wear-resistant, heat resistant barrier for long tool life. Surface Hardness is twice that of high speed steel or tungsten carbide. Coating improves tool life by two to eight times, and reduces cutting forces and temperature by 25%. Drills can be run at substantially higher speeds and feed rates. Cuts closer to size and holds size longer. Drills can be reground, and in many cases still outperform an uncoated drill by a factor of two or more."
There is also a Bright Finish but it's just polished, if you are good and had the time you can do it yourself.
Cobalt- very good bits but expensive.
Carbide-special needs only, expensive.
About 95% of the time I use the TiN coated bits I feel they offer the best overall value. Sometimes for hard materials the expensive bits are needed. I always use new (unsharpened) drills, end mills for jobs (that's jobs that pay) to get good clean holes.
I used to check out goverment surplus from time to time and I always remember seeing these 4' cubic cribs full of used drills (we're talking thousands and thousands of drills) and always wondered what in the world would anybody do with all them bits.
So, if you ever want to give them sharpeners a tryout check gov. surplus.
[This message has been edited by clocker (edited 10 May 1999).]
[This message has been edited by clocker (edited 10 May 1999).]
