Besides titanium and cobalt, drill bit choices also include steel, high-speed steel, black oxide and carbide-tipped. Drill bits vary with respect to how long they stay sharp and the type of application for which they are used. Both of these factors are determined by the materials used to make the bits.
Materials and Coatings
Cobalt bits are made of cobalt steel which makes them hard enough to bore through tough metals such as stainless steel. Cobalt steel also makes these bits dissipate heat rapidly which is a prime consideration when cutting metal. Titanium bits are coated in a titanium ceramic material over a high-speed steel. The coating makes them hard, long lasting bits, and the titanium makes them dissipate heat rapidly as well. Titanium is suitable for wood, plastic and most metals, although cobalt is a better choice for stainless.
Both titanium and cobalt drill bits hold their sharpness for a long time. However, titanium bits cannot be sharpened unless you grind off their coating in the process. The shank of a sharpened titanium bit will retain its coating but the point will be steel only. Cobalt bits take a sharpening many times since they are made of cobalt steel throughout the bit. As a result, cobalt bits remain sharper longer than titanium bits. While it maintains its original strength through many sharpenings, cobalt is a more brittle material, which can cause breakage sooner than titanium bits.