Twist Drill Bits for Metals
If you need to drill into metal, you can't typically expect to use a regular steel or carbon steel drill bit designed for cutting through wood. This is especially apparent when dealing with particularly hard materials and surfaces, such as steel. However, there is a good range of treated, coated and tipped twist drill bits for metal, all of which are manufactured to offer a more robust cutting tool for tackling those tougher metalworking jobs.
The most widely available include titanium twist drill bits and cobalt drill bits. Like regular high-speed steel (HSS) drill bits, these are expressly built for the purposes of drilling through metals. The key difference between titanium and cobalt drill bits is that the titanium versions are toughened with a titanium oxide (or titanium nitride, also known as TiN drill bits) coating, while cobalt steel twist drill bits are crafted entirely from solid cobalt steel.
Although the titanium versions are harder thanks to their oxide coating, this manufacturing process also means that drill bits of this type can’t be sharpened if they dull over time through use on sheet metals. Cobalt steel twist drill bits, on the other hand, can be sharpened as they are made from a solid piece. They are also very abrasive, and particularly good for drilling through hard materials such as titanium, cast iron and stainless steel.
Another good alternative to cobalt steel would be carbide and carbide-tipped twist drill bits, which allow for very high cutting speeds and offer extended tool life. However, with increased hardness, the trade-off is usually a more brittle product, so you will need to assess which is the best cutting tool for your level of experience, the materials you will be working on, and the longevity you are looking for when planning a purchase.