The functional structure of the plastic mold system is mainly composed of six systems: the pouring system, the temperature control system, the molding part system, the exhaust system, the guide system, and the ejection system. Among them, the pouring system and the molding part are the parts that directly contact the plastic and change with the plastic and the products. They are the most complex parts in the plastic mold, which change the most and require the highest processing smoothness and accuracy.

1. Gating system:

The gating system refers to the part of the flow channel before the plastic enters the mold cavity from the nozzle, including the main flow channel, the cold material cavity, the shunt channel and the gate.

2. Formed parts system:

The molding part system refers to the combination of various parts constituting the shape of the product, including the movable mold, the fixed mold, the cavity (female mold), the core (male mold), and the molding rod. The core forms the inner surface of the product, and the cavity (die) forms the outer surface shape of the product. After clamping, the core and cavity form the cavity of the mold. According to the process and manufacturing requirements, sometimes the core and female die are composed of several pieces, and sometimes they are made as a whole. Only the parts that are easy to be damaged and difficult to be processed are used with inserts.

3. Temperature control system:

The temperature control system is to meet the requirements of the injection process on the mold temperature, and needs a temperature control system to adjust the mold temperature. For the injection mold for thermoplastic, the cooling system is mainly designed to cool the mold (or heat the mold). The common method of mold cooling is to open a cooling water channel in the mold, and use the circulating cooling water to take away the heat of the mold; In addition to using cooling water to heat hot water or hot oil, electric heating elements can also be installed inside and around the mold.

4. Exhaust system:

The exhaust system is set up to exclude the air in the medium-sized cavity and the gas generated by the melting of the plastic from the mold during the injection molding process. When the exhaust is not smooth, the product surface will form gas marks (gas lines), scorching and other defects; The exhaust system of the plastic mold is usually a slot shaped air outlet opened in the mold to discharge the air of the original cavity and the gas brought by the molten material.

When the melt is injected into the mold cavity, the air originally stored in the mold cavity and the gas brought in by the melt must be discharged to the outside of the mold through the exhaust port at the end of the material flow, otherwise, the product will have pores, poor connection, insufficient filling of the mold, or even the accumulated air will be compressed to generate high temperature and burn the product. In general, the vent hole can be set at the end of the melt flow in the mold cavity or on the parting surface of the mold.

The latter is to open a shallow groove with a depth of 0.03-0.2mm and a width of 1.5-6mm on one side of the female mold. During injection, there will not be a lot of molten material oozing out of the exhaust hole, because the molten material will be cooled and solidified at this place to block the channel. The opening position of the exhaust port shall not face the operator, so as to prevent accidental spraying of molten material and injury. In addition, the fitting clearance between the ejector rod and the ejector hole, and the fitting clearance between the ejector block and the stripper plate and the core can also be used for exhaust.

5. Guidance system:

The guide system is set up to ensure that the movable mold and the fixed mold can be accurately aligned during mold clamping, and guide parts must be set in the mold. In the injection mold, four groups of guide posts and guide sleeves are usually used to form the guide parts. Sometimes, the inner and outer conical surfaces that coincide with each other are set on the movable mold and the fixed mold to assist in positioning.

6. Ejection system:

The ejector system generally consists of ejector pin, front and rear ejector pin plates, ejector pin guide rods, ejector pin return springs, and locking screws of ejector pin plates. After the products are molded and cooled in the mold, the front and rear molds of the mold will be separated and opened, and the plastic products and their condensates in the flow channel will be pushed out or pulled out of the mold cavity and the flow channel position by the ejector pin of the injection molding machine, so as to carry out the next injection molding work cycle.