What are the components of injection molding?

An injection mold is a tool for producing plastic products. It gives plastic products their complete structure and precise dimensions. Injection molding is a processing method used for the mass production of certain complex-shaped parts.

Specifically, the heat-melted plastic is injected into the mold cavity at high pressure by an injection molding machine, and after cooling and curing, the molded product is obtained.

The injection molding tool consists of two main parts, which include:

Moving mold: The moving mold is mounted on the moving template of the injection molding machine

Fixed mold: The fixed mold is mounted on a fixed template of the injection molding machine.

During injection molding, the moving mold and the fixed mold are closed to form the pouring system and the cavity. Thereafter, the moving mold and the fixed mold get separated to remove the plastic product.

Plastic mold structures are divided by function and which include:

Pouring systems:

This is the part of the runner before the plastic enters the cavity from the injection nozzle and includes the main flow channel, the cold cavity, the manifold, and the gate. The pouring system and molded parts are in direct contact with the plastic and vary with the plastic and the product. They are the most complex and varied parts of the mold, requiring the highest degree of finish and precision.

Molded parts system

It is a combination of various parts that make up the shape of the product, including the dynamic mold, the fixed mold and the cavity (concave mold), the core (convex mold), the forming rod, and other components.

The core forms the inner surface of the product and the cavity (concave mold) forms the outer surface of the product. After the mold is closed, the core and cavity form the cavity of the mold.

According to the process and manufacturing requirements, sometimes the core and concave mold are combined by several blocks, or sometimes they are made into a whole and only difficult-to-process parts use inserts.

Temperature regulation system

To meet the mold temperature requirements of the injection process, a temperature regulation system is required to regulate the temperature of the mold. In the case of thermoplastic injection molds, the cooling system is designed to cool the mold (the mold can also be heated).

The common method of cooling the mold is to open a cooling water channel in the mold using the circulating cooling water to take away the heat from the mold. The mold can be heated by using hot water or hot oil in addition to the cooling water. However, the process can also be done by installing electric heating elements in and around the mold.

Exhaust system

To carry out the injection molding process in the cavity of the air,  plastic melting is generated by the gas out of the mold and set up. A plastic mold exhaust system is usually a slot in the mold to open the air outlet to discharge the original cavity air and melt into the gas.

Guidance system

To ensure that the moving and fixed molds are accurately aligned and set up when the mold is closed, guiding elements must be provided in the mold. In injection molds, four sets of guide pillars and guide bushings are usually used to form the guiding parts. Sometimes it is necessary to set up the inner and outer tapered surfaces on the moving and fixed molds respectively to assist in the positioning.

Ejector system

It generally includes: ejector pin, front, and rear ejector plate, ejector pin guide bar, ejector pin reset spring, ejector plate locking screw, and other parts. When the product is molded and cooled in the mold, the front, and rear molds are separated and opened. Additionally, the plastic product and its condensed material in the runner are pushed out or pulled out of the mold cavity and runner position by the pushing mechanism – the ejector pin in the injection molding machine, to carry out the next injection molding work cycle.

All in all, design experience is particularly important to design molds that are simple to process, easy to assemble, have a long life, are affordable, and form a good product. ZHXTOYS has over 30 years of injection molding experience since its establishment in 1989 and has a total of 70 of its injection molding machines.

We currently work closely with companies all over the world. If you have any ideas, please contact us immediately and we can introduce you to a whole set of processes for the development of our molds and give you an online quote for your injection molds!

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