Multistage Injection Molding: Only for Better Injection Products!

1. What is multi-stage injection molding?

Modern injection moulding products have been widely used in various fields. The shapes of the products are very complex, and the properties of the polymers used vary greatly. Even for products of the same material, due to the different geometry of the runner system and various parts, different parts have requirements for the flow (speed, pressure) of the filling melt, otherwise the rheological properties of the melt in this part, the crystal orientation of polymers, and the apparent quality of products would be affected.

In an injection process, when the screw pushes the melt into the mold, it is required to realize the control of process parameters such as different injection speeds and different injection pressures at different positions. This injection process is called multi-stage injection molding.

The digital dial injection mold maker is relatively backward, with only one or two stages of injection, one stage of pressure retention, and one stage of melt glue control procedures. For some products with complex structures and high appearance quality requirements, it is difficult to set and control the injection speed and other process conditions, causing some appearance defects of plastic injection molding parts that cannot be improved by adjusting injection parameters.

In order to meet the need to improve the appearance quality of injection molded parts and overcome the above problems, injection molding machine manufacturers have developed and produced injection molding machines with multi-level injection, multi-level pressure holding, and multi-level melt functions. This is a skill breakthrough in the injection molding processing industry.

2. The benefits of multi-stage injection molding

The multi-level injection control program can reasonably set the multi-stage injection pressure, injection speed, holding pressure and melt mode according to the structure of the runner, the form of the gate and the structure of the injection molded part, which is beneficial to improve the plasticization effect and improve product quality, reduce defective rate and extend mold/machine life.

Control the oil pressure, screw position, and screw speed of the injection molding machine through multi-level programs, which can improve the appearance of molded parts, improve shrinkage, warpage and burrs, and reduce the uneven size of each injection molded part every time.