How does shrinkage of injection molded products relate to plastic injection molds?
Release Time：
2018-05-28
Source：
1. Injection plastic mold structure affects the shrinkage of injection molded products The form of injection plastic mold gate has influence on the shrinkage of injection molded products. When using small gates, the shrinkage of plastic parts increases because the gates are cured before the end of holding pressure. The cooling loop structure of injection plastic mold is the key of injection mold design. If the cooling loop is not designed properly, the shrinkage difference will occur due to the temperature imbalance around the plastic part, which will lead to oversize or deformation of the product. And in thin-walled parts, the influence of mold temperature on shrinkage rate is more significant. 2. Injection plastic mold parting surface and gate affect the shrinkage of injection molded products Plastic injection mold parting surface, gate pattern and size will directly affect the direction of plastic material flow, density distribution, holding pressure and shrinkage effect and molding time. The use of straight gates and large section gates can reduce shrinkage, but in the case of large anisotropy, straight gates and large section gates shrink along the direction of molten plastic flow and shrink more along the vertical flow direction; on the contrary, when the gate thickness is small, the gate part of the injection plastic mold will solidify in advance, and the plastic in the cavity cannot replenish the molten plastic in time after shrinking, which will make the shrinkage of the product bigger. Point gate cooling and curing speed is faster, when the conditions of injection molding parts allow, you can set multi-point gate on the injection plastic mold, this can effectively increase the holding time, increase the pressure of the mold cavity, reduce the shrinkage rate of the product.
1. Injection plastic mold structure affects the shrinkage of injection molded products
The form of injection plastic mold gate has influence on the shrinkage of injection molded products. When using small gates, the shrinkage of plastic parts increases because the gates are cured before the end of holding pressure. The cooling loop structure of injection plastic mold is the key of injection mold design. If the cooling loop is not designed properly, the shrinkage difference will occur due to the temperature imbalance around the plastic part, which will lead to oversize or deformation of the product. And in thin-walled parts, the influence of mold temperature on shrinkage rate is more significant.
2. Injection plastic mold parting surface and gate affect the shrinkage of injection molded products
Plastic injection mold parting surface, gate pattern and size will directly affect the direction of plastic material flow, density distribution, holding pressure and shrinkage effect and molding time.
The use of straight gates and large section gates can reduce shrinkage, but in the case of large anisotropy, straight gates and large section gates shrink along the direction of molten plastic flow and shrink more along the vertical flow direction; on the contrary, when the gate thickness is small, the gate part of the injection plastic mold will solidify in advance, and the plastic in the cavity cannot replenish the molten plastic in time after shrinking, which will make the shrinkage of the product bigger.
Point gate cooling and curing speed is faster, when the conditions of injection molding parts allow, you can set multi-point gate on the injection plastic mold, this can effectively increase the holding time, increase the pressure of the mold cavity, reduce the shrinkage rate of the product.
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