Introduction of the three plates opening sequence in plastic injection mold manufacturing

The three-plate mold has three parts - one between the runner plate and the cavity plate, the second between the runner plate and the top clamping plate, and the third between the cavity plate and the core plate.

First, when the core is pulled by the injection molding machine, due to the nylon lock between the core and the cavity plate, and no connection or restraint between the runner plate and the cavity plate (in most cases, the small tie bar is also equipped with a spring), the runner plate first separates from the cavity plate under the pulling force at this moment, and then the cavity plate moves backward together with the core plate to a preset distance before being blocked by the block of the small tie bar.

2. The cavity plate continues to move backward through the injection molding machine in order to make the small tie bar also move, which in turn drives the runner plate to move to the preset distance, thus unloading the gate and runner. After the preset distance is completed, the small tie bar and the cavity plate stop moving.

3. The injection molding machine continues to move backward to increase the pulling force to exceed the clamping force of the nylon lock in order to separate the cavity plate from the core plate at the preset distance before stopping.

4. The ejector plate drives the ejector system (ejector, sleeve and lifter, etc.) to start ejecting the finished product (automatically or by mechanical arm unloading) under the push of the ejector of the molding machine.

5. The core moves to the cavity under the push of the injection molding machine. If the top plate is not pulled back earlier, the return pin will first contact the cavity plate. Then, the ejector plate returns through the return pin under the reaction force.

6. Press the core plate against the cavity plate and runner plate until the mold is tightly closed. The nozzle on the injection molding machine is in close contact with the nozzle bushing on the mold, ready for the next molding cycle.

The above is the whole molding cycle of the three-plate mold. #Injection Molds