Work noise is high. Cold stamping is an impact job, and each time it is stamped, it makes a noise. Shear shop is one of the most affected areas of noise pollution. 7, rush cutting speed, pressure is large, prone to personal accidents. Due to the long mold manufacturing cycle and high manufacturing costs, it is not economical to adopt cold stamping technology when the number of workpieces is not large. Only in mass production, the cost of die manufacturing has little impact on the cost of the workpiece, so the cold stamping process becomes an economical and reliable processing method. The type of iron core punch piece is different according to the shape of the iron core punch piece. The iron core punch piece is divided into a round punch piece, a fan-shaped punch piece, and a magnetic pole(shovel-shaped) punch piece. The round punch piece is usually used in the medium and small AC motor and DC electromechanical pivot center. The magnetic pole core of DC motor and synchronous motor is usually pressed by magnetic pole punch. The technical requirements of the iron core punch 1, the size of the bad degree to meet the requirements of the pattern. There are many sizes on the iron core punch, but it can be attributed to the internal size and the match size. Internal dimensions such as grooves, ventilation holes, marking slots, and various diameters on magnetic electrode punching sheets, etc., generally use the H10 accuracy level, and higher accuracy is unnecessary. The error caused by the irregular wall and hole wall after installation is much greater than the error of the punch itself. The size of the match, such as the outer circle of the iron center, the inner circle of the iron center, and the size of the shaft hole to be matched with other parts, the accuracy level is related to the processing process used. 2, the shape deviation must meet the requirements of the pattern. The coaxiality of the inner circle and the outer circle of the stator punch shall not be too poor. When the inner and outer rounds of the punch sheet are pressed at the same time, the coaxial degree is 0.04-0 .06 mm. When the inner and outer parts of the punch are divided into two parts, the coaxial degree can be appropriately relaxed. 3, the alveolar distribution should be uniform. The degree of slot must be accurate, and the difference between the maximum and the minimum tooth width should meet the requirements of the pattern. Otherwise, it will lead to magnetic imbalance. 4, punch thin and uniform, the surface is almost whole, punch cut and the burr on the small. The burr on the small and medium sized motor stator punch shall not be greater than 0.05 mm. The burr of the cast aluminum rotor punch should not be dry 0.1 mm. The insulating layer on the surface of the punch sheet should be thin and uniform, with good dielectric strength, oil resistance and moisture resistance.