In the process of plastic injection molding, there are many factors that affect the quality of products
1. Plastic materials
The complexity of injection molding process is determined by the complexity of plastic material properties. The properties of plastic materials vary greatly due to different varieties, brands, manufacturers and even batches. Different performance parameters may lead to completely different molding results.
2. plastic Injection temperature
The melt flows into the cooling cavity and loses heat due to heat conduction. At the same time, the heat generated by shear action may be more or less than that lost by heat conduction, which mainly depends on the injection conditions. The viscosity of the melt decreases with increasing temperature. In this way, the higher the injection temperature is, the lower the viscosity of the melt is, and the smaller the filling pressure is. At the same time, the injection temperature is also limited by thermal degradation temperature and decomposition temperature.
3. Processing temperature of plastic injection molding
The lower the processing temperature of plastic injection molding, the faster the speed of heat loss due to heat conduction, the lower the melt temperature and the worse the fluidity. This phenomenon is especially obvious when the injection rate is low.
4. Injection time
The influence of injection time on plastic injection molding process is shown in three aspects
(1) When the injection time is shortened, the shear strain rate in the melt will increase, and the injection pressure needed to fill the cavity will also increase
(2) Because of the shear thinning property of the plastic melt, the viscosity of the melt decreases, and the injection pressure needed to fill the cavity also decreases
(3) When the injection time is shortened, the shear strain rate in the melt increases, the shear heat is greater, and the heat lost due to heat conduction is less. Therefore, the higher the temperature of the melt, the lower the viscosity, and the lower the injection pressure needed to fill the cavity