SMC mold Shear edge design

The cutting edge of the mold is the part where the upper and lower molds bite each other, and generally requires flame quenching. During the SMC molding process, the product edges are sandwiched between the cut edges. The raw edge is a useless part of the product, from this point, the gap of the mold cutting edge can be larger. However, if the cutting edge is too large, it is easy to cause material running and pressure relief. This can be solved by adjusting the height of the cutting edge, that is, there are two factors that need to be designed and adjusted when designing the cutting, the gap of the cutting edge and the cutting The height of the side. Shearing edge is one of the most important factors in mold design. Whether the size of the shearing edge is appropriate directly affects whether the product can be molded and whether there are defects during product molding, so it should be strictly required and controlled.

Cutting edge parameter selection table

Mold size parameters




Cutting edge height/MM




Shear edge fit clearance/MM




In our design, if the product can be used as a straight cut edge or a horizontal cut edge, we use straight cut edges as much as possible. It has two advantages: A product will not touch the appearance of the product when trimming the cutting edge. B reduces the projected area of the product, the pressure requirements of the press will not increase.