XingAn. uses compression , transfer and injection molds. On our quotations, we may propose more than one type of mold. To clarify these different molding options, their advantages and disadvantages, we have put together three education/information web pages on molds. The following covers the most sophisticated type of mold, injection.
Figure 1 is an example of a basic vertical type three plate multi-cavity injection mold, however, you are not limited to three plates. The mold does not require heater elements or temperature controllers. The molding temperature is fully controlled by the injection press it is running in.
Molding Procedure: The press opens the mold. It remains in the press. Center plates are separated by the stripper bolts and hang from the top plate. (However, some core bars or plates may be designed to be removed to retrieve the finished molded parts.) When bonding to metal inserts, they are placed into the cavities at this time. The mold is closed by the press and the fully automated injection cycle begins. A large ram or screw forces preheated uncured rubber through the injection nozzle, through the mold's runner system, down through the "sprues" and into the cavities. The uncured rubber is then forced into the shape of the cavity in the mold. A slight excess of material flows out of the cavity, along the gates and vents. The mold remains closed until the rubber is cured, completing the cycle.