Head shape      is the bearing surface formated by the increased Self Tapping Screws into the part of one end of the shape. ANSI / ASME B18.6.4 provides for Self Tapping Screws 13 standard head shapes. According to thread forming and thread cutting on the Self Tapping Screws, the 5 shapes in the 13 kinds - Flat Countersunk, Oval Countersunk, Pan, Hex and Hex washer Head is the most important, these five first-type Self Tapping Screws accounted for almost above 90%, When you are using Self Tapping Screws, you should first consider the five head shapes.

The other five types of Self Tapping Screws concave bearing surface for the Flat Undercut, Flat Trim, Oval Undercut, Oval Trim and post hill Fillister is a relatively minor head type, However, Truss, Round and 100 degrees flat countersunk for the new design did not take into consideration, this is because that the function of the first type can be replaced by others, pan head can be replaced by mushroom head and head, 82 degree flat countersunk head can be replaced 100 degree flat countersunk. thread rolling head Self Tapping Screws with the same type of selection, the main consideration for the use of flat-topped, flat dome, pan head, hex head and hex washer head five. drilling screws with flat , flat dome, pan head, hex washer head, and the most common reason for not using hex head actual cause of the drilling process, the need to exert pressure on the tightening tool to support the drilling tools.

So using the cross flat-topped, flat dome, pan head, or hex washer head. Although the American National Standards only provides 13 standard head shapes, but other commercial uses on the first type and are still in use, such as dry wall screw head used by speakers, pizza head and the other designed for use by the special head type, manufacturer Keyi other materials manufacturing. bearing surface of the basic concept - a support or end pieces of the part positioning, often working through the bearing surface to the Self Tapping Screws. There are two basic types of bearing surface, flat type of bearing surface (a vertical rod with the end pieces) and the conical bearing surface (formed with the shank end pieces of angle) in most cases, the former acting on the end pieces to carry the load force and the service, which continues Flat bearing surface in addition the same function, but also for positioning. with conical bearing surface of the junction pieces are usually buried within the meaning of the first type. the first type of different applications, depending on the initial function of bearing surface and the torque transmission capacity of the head