Top force of injection mold demoulding

In injection molding, the conventional process is to open the mold, inject into the mold cavity after cooling and curing to have a certain strength of the molding product ejection, so as to take out the molding product.

When a molded product is released from a cavity, or pushed out and removed from a core, the surface temperature will be above room temperature because the cavity and core are usually made of steel and the molded product is made of thermoplastic resin. The surfaces of cavities and cores that are machined or polished to a state of surface roughness. And, in general, its hardness and strength are higher than thermoplastic resin molding products. From the physical point of view, it can be inferred that the friction resistance caused by the surface roughness of the cavity and core will greatly affect the release of the molding product from the cavity and core.

The rougher the surface roughness of cavity and core is, the higher the friction coefficient is. And according to the hardness of the resin and self lubricity, the degree of impact is also different. The relationship between the surface roughness of the cavity and core and the friction coefficient with the resin material should also be taken into account when considering the demoulding of the molded product.