90° HSS Industrial Quality Countersink
The five flute rose pattern design has been a principle countersink design for over 100 years. The odd number of flutes reduces chatter on steel, brass and aluminium. Also used for plastic and wood application.
A common use is to allow the head of a countersunk bolt or screw, when placed in the hole, to sit flush with or below the surface of the surrounding material. A countersink may also be used to remove the burr left from a drilling or tapping operation thereby improving the finish of the product and removing any hazardous sharp edges.
Regardless of the name given to the cutter, the surface being generated may be a conical chamfer (plunging applications) or a beveled corner for the intersection of two planes (traversing applications).
A countersink is a conical hole cut into a manufactured object. The same term is used for the cutter used to cut such a hole.