Aluminum caps are often used in medical packaging. Once the quality of the product is problematic, it will directly affect the stability of the drug. Therefore, it is necessary to analyze the factors affecting the quality of the sealing of the small-capacity bottle. The key point is to analyze the quality of the sealing of the aluminum cap and the bottle mouth.
There are two main factors affecting the quality of the aluminum cover: one is the aluminum cover material and the wall thickness of the cover; the other is the radial fit tolerance of the aluminum cover and the bottle mouth and the axial (height direction) tolerance to the seal quality. .
1. The effect of the quality of aluminum in aluminum cover on the quality of sealing
The aluminum cover of the oral liquid preparation material is made of industrial pure aluminum or rust-proof aluminum, and other grades of aluminum may also be used. Under normal circumstances, industrial pure aluminum has high plasticity, low hardness and large retardation rate. The aluminum cover produced by this aluminum material is easy to roll when sealing, so the sealing mouth of the sealing is smooth and smooth, not easy to wrinkle, and covered in the bottle. The fit on the mouth is good. At the same time, the hardness of the aluminum cover HV value is standard in all production plants, too low and too high can not meet the requirements of good sealing.
In addition, the wall thickness of the aluminum cover also has a great influence on the sealing quality and the pass rate. Generally, the wall thickness of the aluminum cover is 0.2 mm, and the variation range is preferably 0.18-0.22 mm. The actual wall thickness of the domestic aluminum cover is 0.14-0.26 mm, and the thin aluminum cover (especially the aluminum cover with a large diameter) is easy to wrinkle when it is sealed. In order to achieve a better sealing effect, the clearance between the aluminum cover and the bottle mouth should be slightly smaller, and the height of the aluminum cover should be correspondingly shorter.
2. The effect of the cooperation between the aluminum cover and the bottle mouth on the quality of the seal
The most susceptible to seal quality is the fit of the aluminum cap to the finish, including the radial fit tolerance of the aluminum cap to the finish and the axial (height orientation) fit tolerance. In the radial fit tolerance group, including the aluminum cover inner diameter D1 and the outer diameter D2 of the bottle mouth, the matching width is generally 0.3mm--0.4mm. When the gap is too small, the white cover process will appear that the "wearing" is not correct and the "wearing" is not on; when the gap is too large, the cover is easy to appear in the rolling process, the shape of the lock is not round, and the sealing is closed. Not strict, easy to loose and so on. In addition, for a thick aluminum cover (0.2--0.26 mm), a larger matching gap can be appropriately selected.
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