What Type of Bit to Use for Cobalt Drilling?

What is Cobalt

• Cobalt is an element that is only found in nature in combination with other metals. It is derived through reductive smelting, where the other metals are separated from it. Once reduced it makes a hard, lustrous silver-gray metal. Most cobalt comes from byproducts of mining heavy ores, such as copper and nickel. Parts with cobalt coatings are often buffed to a blue black finish, which lends its name to the paint color, cobalt.

Standard Bits

• House hold grade drill bits are typically worthless for drilling through anything harder than lightweight steel. Those that are coated with titanium and cobalt may have some effect on thin cobalt surfaces. In general, if you have more than one hole to drill through a very hard surface you will save yourself a lot of time and frustration, as well as potential damage to the surface by avoiding bargain drill bits sold at discount stores.

Premium Bits

• Premium bits have at least a high speed steel core, that should be capable of piercing light to medium weight cobalt, although they will require sharpening immediately afterwards. On the scale of hardness, cobalt ranks just under titanium, so a premium grade titanium coated high speed steel bit is the minimun for cobalt drilling. For the most efficient drilling of cobalt, a diamond coated bit is best, since it is the hardest substance known.

Cutting Oil

• If you are making several holes in cobalt, cutting oil can help tremendously. It helps to reduce friction and can keep the bit sharp longer. A household machine oil, such as that used on sewing machines, or household aerosol lubricants will work well. Start your hole to mark the surface and prevent the bit from "walking". Apply a small amount of cutting oil to the bit and continue drilling. For large holes, or deep holes, apply a small amount of oil into the hole after the surface is penetrated.