Precision injection molding will be affected by many related factors and environmental conditions, and the most basic are the four basic factors of plastic materials, injection molds, injection molding processes and injection molding equipment. In the early stage of designing plastic products, engineering plastics with corresponding performance requirements should be selected according to the application environment.
In addition, precision injection molding should be based on the selected plastic material, finished product dimensional accuracy, part weight, quality requirements and the expected mold structure to select the appropriate injection molding machine.
1) Mold design
Whether the mold design is reasonable will directly affect the quality of plastic products. Therefore, the mold designer must have a wealth of design and injection molding experience, and must consider the relationship between these influencing factors and the injection conditions and their appearance factors when performing precision injection molding.
2) Prevent the error of molding shrinkage rate
Since the shrinkage rate will change due to the injection pressure, for single-cavity molds, the cavity pressure in the cavity should be as consistent as possible. As for the multi-cavity mold, the cavity pressure between the cavities should be very small. In the case of a single cavity with multiple gates or multiple cavities with multiple gates, the injection must be injected with the same injection pressure to make the cavity pressure consistent. For this reason, it is necessary to ensure that the gate position is balanced before precision injection can be carried out.
In order to make the cavity pressure consistent in the cavity, it is best to keep the pressure at the gate entrance consistent. The pressure balance at the gate is related to the flow resistance in the runner. Therefore, before the gate pressure reaches equilibrium, the runners should be balanced.