The small movable circle under the bottle cap is called an anti-theft ring. It can be connected to the bottle cap because of the one-piece molding process. There are two main one-piece molding processes for making bottle caps. The compression molding bottle cap production process and the Injection bottle cap production process. Let Yigui take everyone to understand the manufacturing process of plastic bottle caps!
For injection molding bottle caps, the mixed materials are first put into the injection molding machine. The materials are heated to about 230 degrees Celsius in the machine to become a semi-plasticized state. They are then injected into the mold cavity through pressure and cooled to shape.
The cooling of the bottle cap shortens the counterclockwise rotation of the mold, and the bottle cap is pushed out under the action of the push plate, so that the bottle cap automatically falls off. The use of thread rotation to demould can ensure the complete formation of the entire thread, which can effectively avoid deformation and scratches of the bottle cap. After cutting the anti-theft ring and installing a sealing ring in the bottle cap, a complete bottle cap is produced.
Compression molding bottle caps is to put the mixed materials into a compression molding machine, heat the materials to about 170 degrees Celsius in the machine to become a semi-plasticized state, and extrude the materials quantitatively into the mold.
The upper and lower molds are closed and pressed into the shape of a bottle cap in the mold. The compression-molded bottle cap remains in the upper mold. The lower mold moves away. The cap passes through the rotating disk and is removed from the mold in a counterclockwise direction according to the internal thread. Take it off. After the bottle cap is compression molded, it is rotated on the machine, and a fixed blade is used to cut an anti-theft ring 3 mm away from the edge of the bottle cap, which consists of multiple points connecting the bottle cap. Finally, the sealing gasket and printed text are installed, and then disinfected and cleaned. A brand new bottle cap is completed.
The main differences between the two:
1. The injection mold is large in size and it is troublesome to replace a single mold cavity; each mold cavity in compression molding is relatively independent and can be replaced individually;
2. Compression-molded bottle caps have no traces of the material opening, resulting in a more beautiful appearance and better printing effect;
3. Injection molding fills all the mold cavities at one time, and compression molding extrudes one bottle cap material at a time. Compression molding extrusion pressure is very small, while injection molding requires relatively high pressure;
4. Injection molding bottle caps need to heat the material to a molten flow state, with a temperature of about 220 degrees; compression molding bottle caps only need to be heated to about 170 degrees, and the energy consumption of injection molding bottle caps is higher than that of compression molding bottle caps;
5. The compression molding processing temperature is low, the shrinkage is small, and the bottle cap size is more accurate.
Post time: Nov-30-2023