The head of the hexagonal socket bolt is eccentric or skewed, which may cause serious problems. For example, from the appearance of the product, it is not aesthetically pleasing overall. Another issue is the eccentricity, which can easily cause the production tool to break easily. The most serious problem can also lead to a series of problems such as broken heads of hexagonal bolts.

Hexagon bolts are classified according to the hardness, tensile strength, yield strength, etc. of the screw wire, which is the grade of the hexagon bolt and what grade the hexagon bolt is. Different grades of hexagonal bolts are required for different product materials, and all hexagonal bolts have the following grades: