PVD TiN and Drill Design
Even uncoated drills are surface engineered - they are steam tempered (“blued”) to grow an oxide which provides corrosion resistance, oil retention and low friction.
Under conditions of heat generation at the cutting edge, diffusion between chip and drill causes crater wear which leads to collapse of the cutting edge.
TiN eliminates this wear mode moving failure to the outer corner of the cutting edge where heat generation is highest
Modifications to the drill geometry, to increase the conduction of heat from this corner, results in a drill with a bowed edge (the ADX drill) with significantly longer lifetimes.