Cobalt Drill Bits for Difficult to Drill & Hard Materials

Cobalt drills are made from a special grade of high speed steel (HSS) with cobalt added to the standard HSS alloy. The cobalt gives the drills extra toughness and a little more hardness than ordinary high speed steel (HSS) drills and also increases their resistance to heat damage so that they keep their cutting edges sharp for longer. The extra toughness of cobalt drills also helps if you are machining abrasive materials like fibreglass. One main advantage in repetitive machining operations is that you save time on tool changes because the drills stay sharp longer. A better solution again where you're machining  abrasive materials is to use Diamohard Distegrator Drills - Carbide Drill. These solid carbide drills (see dedicated website page) will increase the length of time between tool changes many times more than cobalt drills because they are much harder. The disadvantage of Diamohard drills is that anything very hard is also brittle and is likely to snap in general use in very hard materials or things like stainless steel and wear plate. In material like this the toughness of cobalt drills helps because of their relative hardness yet toughness.

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Cobalt Jobber Length Drill Sets Inch & Metric

also

HSS Number & Letter Drill Sets

 

HSS Number Drill Sets #1 to 60

                                    #61 to 80

HSS Letter Drills A to Z

 

Metric Cobalt  1mm-13mm x 0.5mm increments

 

Inch Cobalt  1/16" - 1/2" x 1/64th increments