Analysis of injection molding process of two-color plastic products

Injection molding of two-color or mixed-color plastic products is to mix the same raw materials into two different colors, plasticize the melt of two colors by two injection molding machines with the same structure and specifications, and then inject through the nozzle. in the mold. The formed plastic products are color-separated, mixed or irregular, and the appearance effect is not obtained by ordinary injection molding and surface modification.
The alternate plasticized melt of two injection molding machines of the same size is done by nozzle injection and controlled by a programmed control valve between the plasticizing cylinder and the nozzle. The structure of the two-color injection molding machine is such that during plasticizing injection, two plasticizing injection units can simultaneously inject two different colored melts at the same time, the same amount, the same pressure, and the same injection speed through the nozzles of the same rotating mandrel. As a result, injection molded articles with different pattern patterns can be produced in the molding molds. The two plastic injection units and the mold unit have the same specifications and the same structural form. The working method of this injection molding machine is as follows. After the two sets of plasticizing injection devices complete the first injection at the same time, the two sets of molding molds with the same structure rotate 180°C around the central axis, and then the two injection devices inject into the molding molds... By the action of injecting molten materials of different colors into the same molding mold in two steps, two-color injection molded products can be obtained.
The production process characteristics of injection molding two-color plastic products are as follows.
1. The two-color injection molding machine consists of two sets of plastic injection devices with the same structure and specifications. The nozzle should be of special structure according to the production method, or two sets of molding molds with the same structure that can be rotated and transposed. When plasticizing and injecting, it is required that the melt temperature, injection pressure, injection melt volume and other process parameters of the two sets of plasticizing and injecting devices are the same, and the fluctuation of process parameters of the two sets of devices should be minimized.
2. Compared with ordinary injection molding products, two-color injection molding plastic products should adopt higher values of melt temperature and injection pressure parameters during injection. The main reason is that the mold runner of two-color injection molding is relatively long, the structure is relatively complex, and the flow resistance of the injected melt is higher.
3. For two-color injection molded plastic products, raw materials with good thermal stability and low melt viscosity should be selected to avoid decomposition due to high melt temperature and long residence time in the runner. The plastics in many applications are polyolefin resins, polystyrene and ABS materials.
4. When injection molding two-color plastic products, in order to make the melt of two different colors melt well in the mold and ensure the molding quality of injection molded products, a higher melt temperature and a higher mold temperature, higher injection pressure and injection speed.