A diamond bit is a drill bit made with industrial diamonds. Diamond is one of the hardest known materials on Earth, and can be harnessed in a bit to ensure that the bit successfully penetrates very hard materials. This type of drill bit is used in a wide variety of settings, from a jeweler's bench to an oilfield. Many manufacturers of bits also produce diamond bits, and can produce custom bits by request for specific jobs.
A typical drill bit works by biting into the surface being drilled with a sharpened tip. Once the drill gets a foothold, the biting edge of the bit pulls it through the surface to create a hole. With materials like glass, tile, stone, metal, and ceramic, the material is too hard and too slick for a conventional bit. Instead, the bit will generate friction as it spins against the surface, heating the surface and potentially causing it to crack. In addition, the bit can fail as a result of metal fatigue caused by the strain and friction.
In a diamond bit, diamonds embedded into the bit provide the “bite” the bit needs to drill. The diamonds may be attached to the surface or integrated into the bit using a sintering process. Sintered bits are sometimes preferred because as diamonds and bit material are worn away, new diamonds are exposed. This prolongs the life of the bit and eliminates the need to change bits during drilling when really hard materials are being worked or when the hole is extremely deep.
In a diamond core bit, the bit consists of a hollow tube, with diamonds along one end. The diamonds may also rise up into the tube. This type of bit is preferred for large holes, and may include a stabilizer, an anchor in the middle of the bit which helps to hold it in place. Blunt tip diamond bits, used for small holes, have a tip which is covered in diamonds so that the bit can penetrate.
Lubrication such as oil or water is sometimes needed with a diamond bit, especially when it is used on hard materials. The lubrication reduces friction, lowering the risk of breaking the bit or the material it is drilling. Especially when diamonds themselves are being drilled, as in the process of preparing a diamond for use in jewelry, lubricant is critical.
Various types of bits are available for specific applications. When using a diamond bit, operators must be careful to use the speed and pressure most appropriate for the application. Bit manufacturers often issue charts with recommended diamond bit types and sizes, along with pressure and speed recommendations.