You can drill holes in a many ways. Still drilling with a drill bit is most known. Drilling bit comes in many sizes, materials, etc. Drilling usually is performed with a power drill which cuts the material by drill bit rotation. Holes in wood, plastic and other mild materials can be made with any bit, but stainless steel, glass, and so on require specially designed drilling bits. Forstener bits, large diameter core bits and so on should be used with a best drill press. But most of them can be used with a hand power drills.
Conical point with a flat surface and linear chisel are used to improve cutting process, removing chips, and reducing thrust. In automated drilling machines are used multi-faceted drill points. Compared to usual bits, they require only a half of the thrust, and generate more then twice less heat.
The general purpose drill points are usually 118°. They work well for cutting into copper, aluminum, and mild steel, whereas the 135° drill point is good for stainless steel, hardened steel and another tough materials. A 135° bit is flatter, therefore more of its cutting lips start to perform the full metal cutting action.
Coatings help prevent rust, lessen friction and wear. ZiN - Zirconium nitride film adds the strength, decreases friction and improve heat removal. TiN (titanium) coating is adds corrosion resistance and helps to remove heat from the cutting edge. Titanium has a high heat limit and an excellent fatigue limit, similar to steel, but somewhat less on both counts.
Any master working with a sheet metal, boxes or thin mild metal has a Step drill bit (Unibit). Unibits work fast and make relatively clean holes. Unibits come with as one single drill bit that have progressively sized grooves and ridges. So you just need one tool for a variety of jobs. The one thing that you should avoid using step drill bits on is wood because they are known to split the wood.
