|
Titanium and Zirconium nitride drill bits are somewhat like Teflon coated cookware. A coating is involved, that will not last forever. But, while it is intact, works better than the plain surface. Twist drills have evolved from forged finish to high-polished to black-oxide and now Titanium and Zirconium nitride finishes. The life expendancy claim is based on the chips being smoothly led away from the cutting edge reducing heat and not jamming in the hole, snapping off the bit. Standard grey Aluminum Oxide grinding wheels will sharpen the drills, and a new product called a Drill Doctor has a diamond impregnated wheel that will have no problem grinding the new coated bits. Using a cooling/lubricating fluid, combined with frequent backward clearing of your holes should do wonders for your twist drill's life. Intense heat can remove the "temper" from a drill's cutting edge, making it softer, leading to premature dulling, leading to pushing harder on the drill bit, heating the point more, leading to... Well, you can see where this is going.
| 
