What are the causes of unilateral burrs in metal stamping parts?

The reasons for the occurrence of unilateral burrs in metal stamping parts are mainly in the following aspects:
1). Die assembly error. If the punch and the fixing plate are not perpendicular or loose due to wear, or the positioning pin is loose, it cannot be guaranteed that the male and female molds have the correct fixing position.

2) Poor guidance accuracy. The gap between the mold guides is too large and the upper and lower mold center lines do not coincide, which affects the uniformity of the stamping gap.

3). Installation error. When the unguided mold is installed, the position of the upper and lower molds is not accurate, resulting in uneven gaps. The surface of the template or the bottom plate on the mold is not clean, or the screw of the upper mold is not properly tightened, which will cause the working part to tilt.

4) Deformation when the mold is working. For example, the punching hole of the mattress board is too large, the template under the die is too thin, and the rigidity of the die is not enough. In the stamping, the gap is affected by the deformation of the die.

5). The gap between the guide rails of the punch is too large, the parallelism between the bottom surface of the slider and the work surface is not good, or the sliding direction of the slider is not perpendicular to the work surface.

6). When the maximum resistance of the workpiece during stamping exceeds 80% of the nominal pressure of the punch, it is easy for the open punch to deform the "C" shaped bed, so that the center lines of the upper and lower dies do not coincide.

7). The flatness of the sheet is poor. During the metal stamping process, the punch with a smaller diameter is inclined.

8) Due to improper material selection, forging and heat treatment process of the die, the concave die deforms during heat treatment or wire EDM, which affects the uniformity of the die gap.

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