Carbide drills are made from a carbon steel shank and on the tip there is a coating of very durable carbide. Although there are differences between them, carbide tipped drills can be used for metal as well as concrete and stone. When the drilling operation is taking place, a great deal of heat is generated from the friction between the material and the carbide; it is the carbide that stops the tip of the drill from burning. It is suggested that when the drilling operation is happening that the rotational speed of the drill be kept quite low so the heat buildup is minimized. With proper use and the use of cooling fluid, carbide drills can last for a considerable number of operations before it needs to be replaced in the drilling machine.
A carbide tipped drill is the absolute choice when the material to be drilled into is concrete, it can drill repeatedly without dulling or drilling an elongated hole. Although a carbon steel bit without the benefit of a carbide tip can be used, the resulting hole usually is not round; it becomes egg shape as the drill is hunting for the softest route. A carbide tipped bit will go straight through even though it may hit harder stones as it drills.
Although the common term is simply “carbide,” the material is actually tungsten carbide. When this material is produced it is a fine powder which is then compressed under tremendous pressure to form the shape. While tungsten carbide is very strong, it is also very brittle and it takes little to break it. To overcome this problem in drills, the material is mixed with cobalt which turns liquid at a lower temperature than the tungsten carbide. The liquid cobalt actually penetrates the carbide and the resulting material is much stronger.
Carbide drills are normally used when the results demand high precision and tolerances. In many cases a conventional carbon steel bit will actually begin to soften and melt from the heat, this not only destroys the bit but often ruins the work piece as well. When the work piece needs to be exposed to high temperatures before the operation, this is called heat treating and a carbide bit can tolerate the heat of the drilling process through extremely hard base material.
For a wide range of carbide drills that are designed to provide a precision cut in a high temperature environment, turn to Drills n Supplies.
