Structural Classification of Plastic Injection Moulds

Structural Classification of Plastic Injection Moulds

According to the different structures and product requirements of plastic products, the structures of injection molds are also different. Common injection mold structures include single parting injection mold, multi parting injection mold, inclined guide pillar side core pulling injection mold, inclined pin inner core pulling injection mold, and warm runner injection mold.

1、 Injection mould with single parting surface;

The single parting injection mold is also called two plate injection mold, which is commonly used in the injection mold with large water inlet. This kind of mold has simple structure and strong practicability for plastic parts forming, so it is widely used. The defect of this kind of mold is that the gate is large, and a process to remove the gate is often added, and the gate trace will be left on the surface of the product. Therefore, it is suitable for injection molding products with low requirements on product appearance.

2、 Multi parting injection mold;

The multi parting injection mold has two or more parting surfaces, in which double parting surface Z is common. The double parting surface injection mold is often called the three plate mold. Because this mold is often used for the products of point gate injection, it is also called the fine nozzle mold. Double parting surface injection mold is widely used, mainly for single cavity or multi cavity mold with point gate, mold with lateral parting organization set at one side of the fixed mold, and mold with special structural requirements of plastic parts parting in sequence.

The purpose of the first parting is to pull out the aggregate of the runner, and the second parting is to break the feed inlet to separate the aggregate of the runner from the plastic parts, so that the ejected plastic parts do not need to remove the aggregate of the runner.

3、 Injection mould with side core pulling of inclined guide pillar;

When the side wall of the plastic part has the characteristics of through holes, recesses, bosses, etc., the molded parts must be made into laterally movable parts. The entire organization that drives the lateral movement of the core is called lateral core pulling organization or lateral core pulling organization. There are many kinds of lateral core pulling organizations, including inclined guide pillar lateral core pulling, hydraulic core pulling and pneumatic core pulling, among which Z is commonly inclined guide pillar lateral core pulling organization, as shown in Figure 3.25. When opening the mold, the inclined guide pillar first drives the slider to move outward. When the side core is completely out of the product, the ejection organization starts to act to eject the product.

4、 Injection mould with inclined pin inner core pulling;

When there is undercut inside the product, it is required to use the inclined pin to form these undercut positions. This kind of mold with the inclined pin is collectively referred to as the internal core pulling injection mold with the inclined pin. This kind of mold structure is relatively messy, and the diagonal pin organization needs to be added to the mold. When opening the mold, first turn over the front and rear molds, and then the ejection organization of the injection molding machine pushes the top plate of the mold to move toward the demoulding direction. At this moment, the oblique pin gradually comes out of the product's undercut position, and after it is completely released, ejects the product through the ejection organization on the mold.

5、 Warm runner injection mold;

With the development of rapid and automatic injection molding process, warm runner injection mold is gradually being promoted and applied. It is different from the general injection mold in that the plastic in the pouring system will not solidify during injection molding and will not demould with the plastic parts, so this mold is also called runner free mold. The advantages of this injection mold are as follows:

① Basically, the waste free processing is realized, which not only saves raw materials, but also saves the cold material removal process.

② Reducing the pressure loss of the feeding system and making full use of the injection pressure are conducive to ensuring the quality of the plastic parts.

The warm runner injection mold is easy to distinguish. Generally, the mold with the above picture, cable and mold junction box belongs to the warm runner mold.

Therefore, the warm runner injection mold has a disorderly structure, high cost and strict requirements for mold temperature control, which is suitable for mass production.