1. Insufficient blank holder force and improper blanking surface will cause the problem of "inner looseness and outer tightness";
2. Too much lubricant, too many brushing times, or incorrect brushing position;
3. The trial mold blank is too soft and the material strength is low. If the blank size is too small, it will not be compacted;
4. The positioning of the blank is unstable, resulting in local pressing and improper surface shape of the pressing material, resulting in uneven material;
5. The hardware punching direction is incorrect.
