Iron core punching is one of the important parts of motor manufacturing. Punching manufacturing workload is the largest, the most stringent technical requirements, the highest requirements for the mold, is an important factor affecting economic benefits, so we must pay attention to the study of iron core punching manufacturing process and related mold structure issues.

In order to facilitate the study of the structure and technology of the iron core, according to the shape of the chip is divided into circular chip, sector chip and magnetic pole chip. There are a variety of sizes on the chip, which can be classified as "internal size" and "matching size". Internal dimensions such as slot size, ventilation hole, marking slot and magnetic pole punching hole size, etc., generally use H10, higher accuracy level is not necessary, because after stamping, the error caused by inside and out is far greater than the error of the punching film itself. The "fit size" of the inner circle, the outer circle and the shaft hole matched with other parts, and the choice of accuracy level is related to the processing technology used. The precision of stator punching inside and outside diameter of small and medium-sized asynchronous motor is related to its loading mode. The inner diameter is generally H8, and the precision of the outer diameter is related to the process plan to ensure the coaxial degree of the stator. The outer diameter of the internally pressed stator punching is generally H7 and the inner diameter is H8.

Stator punching is generally controlled within 0.05mm. For multiple punching individual parts (length of about 30mm) control within 0.12mm, but should be deburring treatment, treatment should be within 0.08mm. Stator punching is generally controlled within 0.05mm. For multiple punching individual parts (length of about 30mm) control within 0.12mm, but should be deburring treatment, treatment should be within 0.08mm. For the stamping after painting, the burr shall not be greater than 0.05mm.

After punching, there will be different degrees of warping, the warping value of the single slot punching is larger, especially the rotor punching of the closed slot, after single slot punching, the warping is more serious, the punching outer diameter is less than 230mm is not allowed to exceed 2mm, 230mm is not allowed to exceed 3mm. The coaxiality of the inner circle or shaft hole and the outer circle is generally controlled within 0.04 ~ 0.06mm when the inner and outer circle is punched once, and the coaxiality should be appropriately relaxed when the inner and outer circle is punched twice. The uneven tooth distribution (or size teeth), that is, the difference between the maximum and minimum tooth width, should comply with the provisions of the drawings and relevant process documents. Some factories stipulate that the difference between the flow size teeth does not exceed 0.12mm, and the difference between the fixed size teeth does not exceed 0.2mm. The center line of the groove should pass through the center of the circle, there should be no obvious skew phenomenon, and the axial holes (or outer diameters) of the positive and negative two pieces should be aligned when checking, and the distance between the two teeth should not be greater than 0.8mm after the end of the groove root is aligned. The insulation layer on the surface of the punching sheet should be thin and uniform, and have sufficient dielectric, oil resistance, moisture resistance and adhesion properties.