September 2 2018
There are many ways to drill a hole in something. Still drilling with a drill bit is most known. Manufacturers offer many types, shapes, materials, sizes of drill bits. Drilling usually is done with a powered drill which cuts the material by drill bit rotation. You can drill soft materials with most any drilling bit, but hard materials require specially designed tools. Some drilling bits are dangerous to use with handheld drills and require a drilling press. Others are easy enough to use with hand or even hand-powered drills.
Drill bit coatings are intended to lessen friction, wear, and prevent rust. Zirconium nitride coating adds the strength and improve precision drilling because it decreases friction significantly. Titanium coating is strong, adds corrosion resistance. Titanium also is heat-resistant and has an excellent fatigue limit.
The material of the drill bit is important aspect of the tool selection (best drill press). Not all bits will work on all applications. Low carbon steel is soft and dulls quick when drilling hard metals, but they cut wood great. High carbon steels require less sharpening, and hold their effectiveness longer. They can cut both woods and metals. HSS is a type of carbon steel with more complex alloys and it can withstand higher temperatures. High speed drilling causes heating and temperatures can raise dramatically, but high speed steel can undergo it. Tungsten carbide alloys are tough, but brittle and more expensive. Carbide bits are used to drill concrete and tough steel.
Most of the drill bits have 118° drill points. They are typically used for cutting into soft metals such as aluminum, whereas the 135° variant is best suited for hardened materials, such as stainless steel. A 135° drill is flatter than 118°, which means that more of its cutting lips engage with the material surface sooner to begin the full metal cutting action.
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.
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. With the tool you need one tool for a variety of jobs instead of many twist drills with various diameters. The one thing that you should avoid using step drill bits on is wood because they are known to split the wood.