The design of the injection mold is closely related to the variety, performance, shape, structure of the plastic and the type of the injection machine. The products produced by different equipment and materials are ever-changing.
In general, the injection mold is composed of three parts: the gating system, the molded part and the structural part. Among them, the pouring system and molded parts are structures that are in direct contact with plastics, which will change with the changes of plastics and products. They are relatively complex and changeable parts in the mold, and the processing requirements are relatively high.
Dynamic and fixed molds
The movable mold of the injection mold is installed on the movable 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 movable mold and the fixed mold are closed together to form a gating system and a cavity. When the film is opened, the movable mold and the fixed mold will be separated, which is convenient for related personnel to take out the injection molded product.
Gating system
The pouring system is also called the runner system, which is directly related to the molding quality and production efficiency of plastic products. The gating system includes the main runner, cold slug, runner and gate, etc. It refers to the part of the runner before the plastic enters the cavity from the nozzle. It can guide the plastic melt from the injection molding machine nozzle to the mold cavity. In the channel.
Main stream
The main runner is a section of the channel connecting the nozzle of the injection molding machine and the runner or cavity in the mold. The top of the structure is concave, which is convenient for connecting with the nozzle. According to the size of the product, the nozzle diameter is generally 4-8 mm. In order to avoid flashing or blocking due to inaccurate connection, the inlet diameter of the main runner should be larger than the nozzle diameter. In addition, the diameter of the main runner should be enlarged 3°-5° inward to avoid demolding of the runner.
Cold feed hole
The cold slug hole is a cavity set at the end of the main runner to trap the cold slug produced by the two injections at the end of the nozzle to prevent clogging of the runner or gate. The diameter of the cold slug hole is about 8-10 mm and the depth is 6 mm. It is worth mentioning that when the cold material enters the cavity, the product is prone to internal stress.