The production and processing process of pharmaceutical plastic bottle caps is similar to the requirements of the bottle body, except that the main raw material for the bottle body is blow molding grade, while the main raw material for the bottle cap is injection molding grade. The production process of pharmaceutical plastic bottle caps is injection molding.
The main process of this technology is:
Firstly, material addition. The material mixture is mainly transported to the injection molding machine hopper by pipelines. After the machine is opened, the material in the hopper enters the feeding barrel, completing the process of feeding the machine.
Secondly, plasticization is the process of heating the plastic material mixture that enters the feeding barrel into a flowable state with good plasticity. The requirement is that the plastic should reach the specified forming temperature before entering the mold cavity, and provide a sufficient amount of molten plastic within the specified time.
Thirdly, injection. The plasticized melt is injected into the mold under the pushing pressure of the screw (injection process). When the molten material enters the injection mold cavity, it needs to pass through the nozzle, main (branch) runner, and gate, and the resistance is high. The injection pressure loss is 30%-70%, so the process requires sufficient injection pressure to ensure complete filling. Then comes the molding stage, which includes four steps: mold release, compaction, backflow, and gate solidification. The plastic melt injected into the mold cavity is cooled and shaped into a plastic cap.
Fourthly, cooling and demolding. It mainly refers to the stage from the complete freezing of the plastic at the gate to the stage where the cap is released from the mold. Demolding can be achieved through strong demolding and rotary demolding.