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When producing injection molds, there are often many factors that can affect the quality of the product. In summary, there are mainly four points:

1) Plastic materials

The complexity of plastic material properties determines the complexity of injection molding processes. The performance of plastic materials varies greatly due to different varieties, grades, manufacturers, and even batches. Different performance parameters may lead to completely different forming results.

2) Injection temperature

The melt flows into the cooled cavity and dissipates heat due to heat conduction. At the same time, due to shear action, heat is generated, which may be more or less dissipated than heat conduction, depending on the injection molding conditions. The viscosity of the melt decreases with increasing temperature. In this way, the higher the injection temperature, the lower the viscosity of the melt, and the lower the required filling pressure. At the same time, the injection temperature is also limited by the thermal degradation temperature and decomposition temperature.

3) Mold temperature

The lower the mold temperature, the faster the heat dissipation due to thermal conduction, the lower the temperature of the melt, and the poorer the fluidity. This phenomenon is particularly evident when using a lower injection rate.

4) Injection time

The impact of injection time on the injection molding process is manifested in three aspects:

(1) By shortening the injection time, the shear strain rate in the melt will also increase, and the injection pressure required to fill the mold cavity will also need to be increased.

(2) By shortening the injection time, the shear strain rate in the melt increases. Due to the shear thinning characteristics of plastic melts, the viscosity of the melt decreases, and the injection pressure required to fill the mold cavity also needs to be reduced.

(3) Shortening the injection time increases the shear strain rate in the melt, resulting in greater shear heating and less heat loss due to thermal conduction. Therefore, the higher the temperature of the melt, the lower the viscosity, and the lower the injection pressure required to fill the mold cavity. The combined effect of the above three conditions results in a "U" shaped curve of the injection pressure required to fill the cavity. That is to say, there is an injection time at which the required injection pressure is minimal.