Inspection and correction of drawing die: The drawing die needs to be inspected and maintained regularly to reduce the occurrence of convexity and concavity and maintain a stable state. The usual practice is to check the adhesion scratch of the blank holder and the machining surface (fillet of female die and fillet of male die) with samples. Inspection and correction of shearing die: The reason for convexity and concavity after shearing process is that iron powder is produced during shearing, so iron powder must be observed before stamping to avoid convexity and concavity.

Appropriate manipulator speed: For semi-automatic drawing die production, when the drawing punch is in the lower die position and the manipulator speed is fast, burrs will fall on the upper part of the punch, causing convexity and concavity. In order to avoid this problem, we can do the discharging test of the parts before production, and set the manipulator speed and discharging angle reasonably so that it will not touch the parts and the lower die.

Check the cut-off surface: when cutting the coil, the wear and tear of the cutting die will produce a lot of tiny iron powder attached to the cutting edge, so it is necessary to check the double cut-off surface in the material area or stamping line before stamping production, and clean the sheet in time to remove burrs.

Inspection of sheet metal cleaning device: It is necessary to check and trim the cleaning and settling before stamping production, so that it may clean the sheet metal more effectively. It is also necessary to pay attention to the gap between rollers and the quality of cleaning oil. The detailed method is to paint a steel plate with red paint to make it clean and settle at the end. At present, check the cause and shape of the red paint being withdrawn. If the removal rate is not up to standard, it must be checked and trimmed and settled. When the cleaning oil is lacking, it must be cut in time.