1. The inner surface of draft water is not smooth, cracked or metallized.
The transition part of the hammer head has corner edges and wear tools.
3. The residual iron oxide scale of cold-drawn seamless steel tube blank has not been pickled.
4. When lubricants are used, the phosphating and saponification processes cannot be operated properly.
5. Internal and external moulds have been seriously damaged or worn out.
6. Uneven intermediate annealing and insufficient deformation