The so-called two-color injection molding refers to the molding method of injecting two different colors of plastic into the same mold. It can make the plastic part appear two different colors, and can make the plastic part present regular pattern or irregular moire pattern, in order to improve the practicability and beauty of the plastic part.

The principle of double mixed color injection molding has two barrels, each barrel has the same structure and use as the ordinary injection molding barrel. Each barrel has its own passageways connected with the nozzle, and the opening and closing valve 2,4 is also installed in the nozzle passageway. When the melt is plasticized in the barrel, the order of melt entering and discharging into the nozzle and the ratio of melt discharging are controlled by the opening and closing valves 2 and 4, and then the melt is injected into the mold cavity from the nozzle. All kinds of plastic products with different mixing effects can be obtained.