Countersinking and countersinking are technological operations for machining holes. Despite the similarity of names, these operations differ in their purpose and applied technological tool.
Countersinking and countersinking are different holemaking operations. Countersinking is designed to improve the surface quality of holes made by drilling, casting, or forming. Unlike countersinking, countersinking produces recesses in the holes for countersunk fasteners. Countersinks are used for countersinking operations, and tapered and cylindrical countersinks are used for countersinking.
Purpose and features of countersinking
The purpose of countersinking is to improve the accuracy and roughness of the holes. This operation refers to the stage of semi-finishing and is located in the technological process between drilling and reaming. In addition to improving the quality of the surface made by drilling, countersinking is also used to process holes obtained as a result of casting and forming. The tool for countersinking operations is a countersink, which looks like a drill.
Due to the greater number of cutting edges in comparison with a drill, an increased surface finish is achieved with the help of a countersink. The presence of 3-4 cutting edges provides a smooth distribution of forces in the contact zone of the tool and the workpiece. Also, the countersink differs from the drill in the original geometry of the cutting part, which is due to the need to process already existing holes without removing material in the longitudinal direction.
Purpose and features of countersinking
Countersinking is intended to obtain on the ends of the holes of the slots for the countersunk placement of the heads of fasteners. These recesses, which can have a cylindrical or conical shape, are machined, respectively, with conical or cylindrical countersinks.
The geometry of the cylindrical countersink resembles a countersink, and the working part of the conical countersink has serrated cutting edges instead of spiral cutting edges. In the design of a cylindrical countersink, a guide belt must be provided. Tapered countersinks are also used for deburring sharp edges and chamfering.
Equipment
Countersinking and countersinking operations are performed on the same technological equipment as drilling. Such equipment can be a drilling machine or a universal machining center. There is also the possibility of countersinking and countersinking using a lathe. It is not recommended to perform these operations with a hand-held tool due to the impossibility of ensuring the required accuracy of its positioning.
