The size of plastic caps is a multidimensional integrated system, not just a single diameter or height. It usually consists of the following key dimensions and features, which together ensure a perfect match and functional implementation between the bottle cap and the bottle mouth.
Core components of plastic cover size
1. Diameter Dimensions
This is the most important size group, which determines the basis for the fit between the bottle cap and the bottle mouth.
Outer diameter (OD): The diameter of the outermost edge of a bottle cap. This mainly affects the appearance, touch, and label design.
Thread Diameter/Pitch Diameter:
This refers to the diameter of the circle where the internal threads of the bottle cap are located.
This is the most critical cooperation size, which must match the diameter of the external thread of the bottle mouth perfectly in order to smoothly tighten and open.
Usually measured in millimeters (mm), such as 28mm, 33mm, 48mm, etc.
Plug Diameter/Inner Seal Diameter:
If the bottle cap has an inner stopper (a cylindrical structure that extends into the bottle mouth), this size refers to the outer diameter of the inner stopper.
It must fit tightly with the inner diameter of the bottle mouth, which is the primary barrier to achieve leak prevention and sealing.
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