Why is there a line under the head of a long m5 screw?

Mr. Wang bought a long m5 screw of the same specification from different screw manufacturers, but when he looked under the head of the screw, he found that there would be a line under the head of some screws. Why is this?

There is a line under the head of the general long m5 screw, this is the closing line. This is a molded clip and is formed naturally. The clamping line like this will not affect the assembly, its size is small, and it will not be above the rod of the screw, it will only appear below the head of the screw for a certain distance, and will not appear below. The presence of a die line also indicates that the screw was cold-upset molded once, rather than welded. The strength of the screw produced in this way will be more stable and will not break easily.

Of course, some customers will feel that the clamping line under the head of the long m5 screw will affect the assembly effect, will worry. If the customer is really worried, the screw manufacturer can also help to remove the closing line. However, if you want to remove the die line, then you need to add a process, the cost of screws will rise. Therefore, the need to remove the die line, according to their own actual to decide.