Characteristics of bottle cap injection molds.

1. Extremely high production efficiency and automation level
Multi cavity design: Bottle cap molds commonly use high cavity designs, including 32 cavity, 48 cavity, 64 cavity, 96 cavity, and even 144 cavity or more. This is the key to achieving low-cost, large-scale production.

Hot runner system: A needle valve hot runner system must be used. Its advantages include:

Reduce waste (anhydrous raw materials) and save raw materials.

Ensure balanced filling and consistent pressure in each cavity, and ensure uniform quality of each bottle cap.

Cooperate with robotic arms to achieve fully automatic cyclic production.

Rapid opening and closing of molds and ejection: The mold has a very short operating cycle, usually only 3-8 seconds per cycle, requiring stable, reliable, and minimal wear of the mold.

2. Extremely high requirements for product accuracy and consistency
Sealing: The size of the inner gasket (anti-theft ring, inner plug) and the thread of the bottle cap must be extremely precise to ensure perfect sealing with the bottle mouth (sealing, carbon dioxide barrier, etc.). This requires the machining accuracy of mold-related parts to reach the micrometer level.

Dimensional stability: In millions or even billions of productions, the weight, size, and wall thickness of each bottle cap must be highly consistent, which places strict requirements on mold steel, cooling systems, and processing accuracy.

3. Unique mold structure and action
Thread demolding mechanism: This is the core of the bottle cap mold. There are mainly two ways:

Strong thread stripping: suitable for flexible materials such as HDPE. The mold is designed with inclined or convex wheel-type anti-rotation ribs, which use the elasticity of plastic to force the bottle cap to be "unscrewed" from the threaded core when pushed out. The structure is relatively simple, and the cycle is fast.

Rotating thread removal: suitable for materials with strong rigidity, such as PET and PP. By using an oil cylinder/hydraulic motor+gear rack/worm wheel drive, the threaded core is rotated to smoothly unscrew the bottle cap. The structure is complex, but the product thread quality is good, and there is no deformation.

Bottle cap anti-theft ring forming mechanism: The anti-theft ring (commonly known as the "safety ring") below the bottle cap is connected to the bottle cap body through a series of very small bridge points. Precision sliders or slanted tops need to be designed on the mold to form these bridge points, and the bridge points should be accurately cut during mold opening, so that the anti-theft ring remains at the bottle mouth and the bottle cap is pushed out.