1. Head look
The head looks varied. There are round mouth (semi-circular head), oblate head, round flange (with pad), oblate head flange (with pad), pan head, pan head flange (with pad), countersunk head, Semi countersunk head, cylinder head, curved cylinder head, speaker head, hexagon head, hexagon flange pan head, hexagon flange (with pad) first class.
2. Twisting method
The screwing method refers to the method of twisting the head of the screw when installing and fixing the screw. Basically, there are two methods: external screwing and internal screwing. Generally speaking, the allowable torque of external wrenching is more than that of other methods of internal wrenching (concave groove).
Outer wrench screw: Hexagon, hexagon flange, hexagon flange, hexagon flower type, etc.;
Internal wrench screw: slotted, cross grooved H type, cross grooved Z type, cross grooved F type, square groove, compound groove, internal spline shaft, internal hexagonal flower type, internal triangle, internal hexagon, internal 12 angles, Clutch groove, six-leaf groove, high torque cross groove, etc.
3. Thread type
There are many types of threads, such as self-tapping thread (wide thread), machine thread (general thread), dry wall screw thread, fiberboard screw thread, and some other unique threads. In addition, the thread can be divided into single index circle diameter (double-ended), double index circle diameter (multi-point), multi index circle diameter (double-ended) and multiple threads with multiple threads, etc.
4. End way
There are two key ways of tail end: cone end and friendship end. However, according to the application requirements, the screw part of the tail end can be used to produce grooves, grooves, cuts or parts similar to twist drills that have the function of drilling. In some specifications, the tapered end or flat end is the same, but there are also different ways such as round end.
