Drilling holes in steel is not a daily home repair activity, and metal drill bits are the most expensive. Normal bit can\'t wear steel so you need a heavy bit Do the work diligently. In the metal processing project, you can rely on two kinds of drill bits: titanium and cobalt. High titanium drill- Speed steel drill bit (HSS) It is coated with titanium oxide. They are very hard, corroded-resistant. They have a much longer life than ordinary hs drill bits and are conducive to cutting any metal, including metal plates. The titanium drill bit is harder than cobalt, but cannot be sharpened because it is coated. The cobalt drill is made of cobalt steel and can be sharpened. They also have high heat resistance, are very hard and wear-resistant. They are especially good for drilling through stainless steel, cast iron and titanium.