What is the function of Cartridge Heater in injection molding?

Cartridge heaters are an important part of the injection molding process. They are cylindrical heaters that get their name from their resemblance to a cartridge. In injection molding, cartridge heaters are used primarily for precise heating.

The injection molding process begins with the melting and heating of plastic pellets. These pellets are loaded into the hopper of the injection molding machine and are conveyed to the heating barrel by a heating system and a rotating screw. At this stage, the cartridge heaters installed around the mold are activated and begin to heat the mold and conduct heat to the interior of the mold.

As the plastic pellets are heated to their melting temperature in the heating barrel, they become a viscous melt ready to be injected into the mold. This process requires ensuring that the molten plastic has sufficient fluidity to fill all the details and gaps in the mold cavity, while also ensuring that the temperature is controlled properly to prevent the plastic from overheating or burning.

Once the molten plastic reaches the appropriate fluidity and temperature, the injection unit of the injection molding machine starts to work, injecting the molten plastic into the pre-designed mold cavity. During the injection process, the cartridge heaters continue to heat the mold, ensuring that the mold temperature remains constant and effectively transferring heat to the plastic material to keep it in a flowing state.

Once the plastic is filled, the injection molding machine stops injecting, and the molten plastic in the mold begins to cool and solidify inside the mold. At this stage, the heating function of the cartridge heaters is also paused, and the mold relies on its internal cooling system to lower the temperature, thereby solidifying the plastic.