How Does an Injection Molding Machine Work?

Jun. 02, 2021

Injection Molding Machine is a complex machine that injects molten material into a mold through a reciprocating screw system to create a solid part. This machine is made up of many components; it consists mainly of a hopper, a barrel containing a reciprocating screw, a temperature control device, a clamping device and the injection mold itself.

The process begins with the creation of a mold. The mold is created by the mold maker according to the specifications given to them by the designer or engineer through a model generated by a 3D computer. The mold is carefully constructed so that the two halves of the mold - the cavity and the core - are separated along a dividing line. This allows the part to be easily ejected from the injection molding machine as it cools. If the mold is not designed correctly, the part may get stuck in the mold, leading to possible damage.

Injection Molding Machine

Injection Molding Machine

Before the Injection Molding Processbegins, the machine specifications and components must be carefully set. The temperature and pressure will be programmed according to the size and shape of the mold and the material of the part. Once the machine is set up, the cycle will begin and the machine will be ready to work its magic unattended.

Injection molding process:

The raw material and color are fed into the machine's barrel through a hopper. In the barrel, the raw materials are subjected to pressure and temperature until they are melted and malleable. A reciprocating screw inside the barrel will turn to inject the now-molten plastic into the injection mold at a set and controlled temperature, pressure and speed with precision. Once the mold is filled with molten plastic, the injection process will be shut down.

The part is then allowed to cool until it is ready to be removed from the mold. This may take some time, depending on the material, wall thickness, overall size and shape of the part being made. After cooling, the mold will automatically open.

The mold has an ejector mechanism which ejects the part in preparation for a new cycle. If a portion of the finished part is still clamped in the mold at this point, the mold will reopen until the part is fully ejected. As the part leaves the machine, the hopper will release more raw material and color into the barrel and a new cycle will begin. The autonomy of the injection molding machine means that once programmed, it can be left unattended and can run continuously throughout the day and night.

The basic concept of a plastic molding machine has been around for more than seventy years. Since then, the original idea - injecting molten plastic into a mold - has evolved tremendously into an efficient, elegant and versatile tool for making everyday items.

If you would like to learn more about Plastic Injection Molds and the process behind them, please feel free to contact us

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