Countersinking is used to machine the end face of a hole into flat, cylindrical, conical, and other profiled surfaces. Countersinking is used when machining cylindrical countersunk holes, conical countersunk holes, and end face bosses on pre-machined holes.
A flat-bottomed countersink has one or more cutting teeth on its circumference and end face. A guide post is inserted into the pre-machined hole to control the coaxiality error between the countersinked hole and the original hole. The countersunk recess is machined downwards.
An inclined hole countersink has an automatic centering function. Generally, machining conical holes (countersunk recesses) from flat holes does not require a guide post; however, the drill bit must be perpendicular to the plane of the hole. Conical countersinks are available with various drill tip angles of 60°, 75°, 82°, 90°, 100°, 110°, and 120°. Different angles can be customized according to actual needs.
