What are the internal structures of injection molds?

Update:06-12-2019
Summary:

Although the structure of the mold may change from time […]

Although the structure of the mold may change from time to time due to the type and performance of the injection mold, the shape and structure of the plastic product, and the type of the injection molding machine, the basic structure is the same. The mold is mainly composed of a pouring system, a temperature adjustment system, a forming part and a structural part. Among them, the pouring system and the forming part are in direct contact with the plastic and change with the plastic and the product. They are very complicated and diverse parts in the mold, and require high processing accuracy . The injection mold is composed of a movable mold and a fixed mold. The dynamic mold is installed on the mobile template of the injection molding machine, and the fixed mold is installed on the fixed template of the injection molding machine. During the injection molding process, the dynamic mold and the fixed mold are closed to form a pouring system and a cavity. When the mold is opened, the dynamic mold and the fixed mold are separated to take out the plastic product. In order to reduce the heavy workload of mold design and manufacturing, most injection molds use standard mold bases.

It is the channel connecting the main channel and various cavities in a multi-slot mold. In order for the melt to fill the cavities at the same speed, the arrangement of the split grooves on the mold should be symmetrical and equidistant. The shape and size of the shunt section have an impact on the flow of the plastic melt, the release of the product, and the difficulty of mold making. If the flow is equal to the amount of material, the resistance of the flow channel with a circular cross section is small. However, because the specific surface of the cylindrical flow channel is small, which is not conducive to the cooling of the flow distribution channel, the flow distribution channel must be arranged on the two halves, which is laborious and difficult to align.

Therefore, it is often used for splitting in ladders or semi-circular sections, and is set in half of the mold and release lever. The runner surface must be polished to reduce flow resistance and provide faster filling rates. The size of the runner depends on the type of plastic, the size and thickness of the product. For most thermoplastics, the cross-section width of the shunt channel does not exceed 8m, the extra-large cross-section width can reach 10 × 12m, and the ultra-small 2≤3m. Under the premise of meeting the requirements, the injection mold processing should reduce the cross-sectional area as much as possible to increase the sub-flow and extend the cooling time.