The working principle of an injection molding machine is similar to that of a syringe. Under the push of a screw, plastic is injected into a closed mold cavity, and solidified and shaped in the closed mold cavity to obtain a product. This process mainly includes four stages, namely: filling, holding pressure, cooling, and demoulding, which is a complete and continuous process. Next, I will tell you the specific production process of the injection molding machine.

Fill

The first step in the injection molding process is filling. The filling speed directly affects the molding efficiency. It can be divided into high-speed filling and low-speed filling. Generally, the weld line strength in the high temperature zone is better. Under high temperature conditions, the polymer has better chain activity, the thermodynamic properties of the melt are basically the same, and the strength of the fusion zone increases. On the contrary, low-temperature welding strength is poor.

Keep pressure

In the pressure holding stage, continuous pressure is applied to the melt in order to increase the density of the plastic and try to avoid the shrinkage of the plastic. During the pressure holding process, the plastic flow rate is low, and the flow no longer plays a leading role. The pressure holding process is mainly affected by pressure factors. In the high pressure area, the plastic will be denser, while the low area will be loose, and the density distribution of each part will be different. In the process of holding pressure, the plastic has been filled in the mold cavity, and there is a tendency to open the mold under pressure. Therefore, when choosing an injection molding machine, try to choose a large clamping force to effectively ensure the pressure holding.

Cooling phase

In the entire molding cycle, the cooling time accounts for about 70%-80%, which directly affects the output of plastic products. The factors that affect the cooling of the product include the design of the plastic product, the mold material, the configuration of the cooling water pipe, and the nature of the cooling liquid. Pay attention to the rules of setting up the cooling system to ensure uniform and rapid cooling effect

Demoulding stage

This link is the last link of injection molding. At this time, the product is cold-solidified and the demoulding method is improper, which will cause the product to be deformed due to uneven force. Demoulding methods mainly include ejector pin demoulding and stripping plate demoulding. The specific choice of demoulding method depends on the structural characteristics of the product.