What Are The Components Of Injection Molding Tooling?

Views: 44     Author: Site Editor     Publish Time: 2021-05-10      Origin: Site

Injection molding tooling consists of two parts: a movable mold and a fixed mold. The movable 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 injection molding, the movable mold and the fixed mold are closed to form a pouring system and a cavity. When the mold is opened, the movable mold and the fixed mold are separated to take out the plastic products. In order to reduce the heavy workload of mold design and manufacturing, most of the injection molds use standard mold bases.

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plastic injection molding

Gating system

The gating system refers to the part of the runner before the plastic enters the cavity from the nozzle, including the main runner, cold material cavity, runner and gate, etc. The pouring system is also called the runner system. It is a set of feed channels that lead the plastic melt from the nozzle of the injection machine to the cavity. It is usually composed of a main runner, a runner, a gate and a cold material cavity. It is directly related to the molding quality and production efficiency of plastic products.

Main stream

The main runner is a passage in the mold that connects the nozzle of the injection molding machine to the runner or cavity. The top of the sprue is concave to connect with the nozzle. The diameter of the main runner inlet should be slightly larger than the nozzle diameter (0.8mm) to avoid overflow and prevent the two from being blocked due to inaccurate connection. The diameter of the inlet depends on the size of the product, generally 4-8mm. The diameter of the main runner should be expanded inward at an angle of 3° to 5° to facilitate the demolding of the runner.

Cold slug

The cold slug hole is a cavity at the end of the main runner to trap the cold slug generated between the two injections at the end of the nozzle to prevent blockage of the runner or gate. Once the cold material is mixed into the cavity, internal stress is likely to occur in the manufactured product. The diameter of the cold slug hole is about 8-10mm and the depth is 6mm. In order to facilitate demolding, the bottom is often borne by the demolding rod. The top of the stripping rod should be designed in a zigzag hook shape or set with a recessed groove, so that the sprue can be pulled out smoothly during demolding.


The runner is the channel connecting the main runner and each cavity in the multi-slot mold. In order to fill the cavities with the molten material at the same speed, the arrangement of the runners on the mold should be symmetrical and equidistant. The shape and size of the cross-section of the runner have an impact on the flow of the plastic melt, the demoulding of the product and the difficulty of mold manufacturing.


It is the channel connecting the main runner (or branch runner) and the cavity. The cross-sectional area of the channel can be equal to the main flow channel (or branch channel), but it is usually reduced. So it is the smallest cross-sectional area in the entire runner system.

Temperature control system

In order to meet the requirements of the injection process on the mold temperature, a temperature adjustment system is required to adjust the mold temperature. For injection molds for thermoplastics, a cooling system is mainly designed to cool the mold. The common method of injection molding tooling 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; the heating of the mold can not only use the cooling water channel hot water or steam, but also in the injection molding tooling Install electric heating elements inside and around.



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Guangdong, China 523710  
Email: mark.li@goodtech-mfg.com 


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