Machine Screws: Divided into many varieties due to head shape and groove shape. The head type has a cylindrical head, a pan head, a countersunk head and a semi-recessed head. The head groove shape is generally a slotted (slotted groove), a cross slot and a hexagonal slot. When the Phillips screw is screwed, the neutrality is good, the strength of the head is larger than that of the slot, and it is not easy to be bald. It is generally used in mass production. Hexagon socket head cap screws and hexagon socket type screws can apply a large tightening torque. The connection strength is high and the head can be buried in the body for a compact and smooth joint. See GB65, GB67~69 and GB818~820;
Set screw: The set screw is used for the relative position of the fixed part. The head has a type of slotted, hexagonal and square head. The square head can apply a large tightening torque, the top tightening force is large, and it is not easy to be bald, but the head size is large, it is inconvenient to be buried in the part, and it is unsafe, especially the moving part is not suitable for use. The inner hexagon with a slotted groove makes it easy to sink into the part.
The end of the set screw is usually the most commonly used, including the tapered end, the flat end and the cylindrical end. The tapered end is suitable for parts with low hardness; when using the tipless end screw, the hole is to be punched on the top surface of the part, and the cone is pressed on the side of the pit. The end of the flat end of the screw, the contact area is large, the top is not damaged after the surface of the part, used to tighten the hard surface or adjust the position frequently. The screw with the end of the cylinder end does not damage the surface of the part. It is often used to fix the parts mounted on the tube shaft (thin-walled part). The end of the cylinder end is inserted into the hole on the shaft. The round end is resistant to shearing and can transmit a large load. . See GB71, GB73-75, GB77-78, etc.;