Technique

Multi-step cold forging process in hexagon bolt forming- 4 stages

by extrution with small shaft for forming the big flat head. It takes time on this process and no matter about length of material.

is pre-forming the round head, and this stage takes shorter during pre-process. The cabibility of forming is small(The effective forming is not obviously). Within this stage, complete extruction on workpiece, is ready for next stage of forming the flat round head. The more pre-forming material is, the bigger head will be formed.

takes shortest working time and the baverrage/effective stress/forging force, the bigger diameter on head, the bigger forming power will be. Thus, the 3rd stage owns the shortest life compare to 1st and 2nd stage.

Some fasteners formed with wrong appearance or dimension due to not use enough stages. More multi-satges will better performed the products.