By varying the drill tip design, one can optimize the machining of different types of material.
A standard twist drill has a tip angle of between 115 degrees and 145 . By changing this angle, you can create optimal cutting and chip removal for different types of materials. For example, a flat angle  may be advantageous for drilling copper and a FORWARD angled drill bit may be advantageous for drilling thinner plates to minimize burr formation and deformation.
There are also special grinding applications where the drill bit part closest to the center line has a GREATER angle than the portion of the bit that is further out toward the drill edge.