1.Considering the work efficiency of processing and assembly, the types of standard parts should be minimized in the same machinery or engineering.
2.From the perspective of economic considerations, commodity standard parts should be preferred.
3.According to the expected use requirements of the standard parts, the selected varieties are determined according to the type, mechanical properties, precision and thread.
Screw:
1 Machine screw: It is divided into many varieties depending on the head type and the groove type. The head type has a cylindrical head, a pan head, a countersunk head and a semi-recessed head, and the head is shaped into a slot (a word) and a cross slot. See GB65, GB67-69 and GB818-820.
2 set screw: The set screw uses its tail end to prevent mutual displacement between the workpieces and to transmit less torque. See GB71, GB73-75, GB77, GB78, etc.
3 Hexagon socket head cap screws: Hexagon socket head cap screws are suitable for applications where the installation space is small or the head of the screw needs to be buried. See GB70, GB6190, GB6191 and GB2672-674.
4 special purpose screws: such as positioning screws, see GB72, GB828, GB829; do not pull out the screws, see GB827-839, GB948, GB948 and eyebolts, see GB825.
