Bolts are used for fastening in machinery, construction, and electrical industries. One end is a hexagon head for wrench fastening, and the other end is a thread. The length of the thread varies according to the use of different threads. It is divided into full thread and half thread.
Bolts are generally divided into two types: GB30 bolts and GB21 bolts. The difference is that the hexagonal head of GB30 is larger than that of GB21. The materials are all made of: Q235. The grade is 4.8, the hardness is weak, and it is used for parts with low hardness requirements and infrequent activities, so-called ordinary bolts. The most typical use: fixing and fastening in machinery industry and construction industry.
M=the diameter of the thread L=the length of the screw. For example, M24×70 means that the diameter of the bolt is 24mm and the length of the screw is 70mm (excluding the hexagonal head)
National standard bolts are the most commonly used type of fasteners and can be used in all walks of life, such as the fixing of air conditioners and the fixing of various machinery, including machinery, electrical appliances, electronic products, and construction industries. .