Aluminum caps are often used in medical packaging. Once there is a problem with their quality, it will directly affect the stability of the drug. Therefore, to analyze the factors that affect the sealing quality of small-volume bottles, the key point is to analyze the matching quality of the aluminum cap and the bottle. Today we will come to analyze with you. There are two main factors affecting the quality of aluminum caps: one is the material of the aluminum cap and the wall thickness of the cap body; the other is the influence of the radial fit tolerance of the aluminum cap and the bottle mouth and the fit tolerance of the axial direction (height direction) on the sealing quality .

1. The influence of the quality of the aluminum material in the aluminum cover on the sealing quality

The aluminum cover of oral solution is made of industrial pure aluminum or rust-proof aluminum, which meets the requirements, and other brands of aluminum may also be used. Under normal circumstances, industrial pure aluminum has high plasticity, low hardness, and high delay rate. The aluminum cap produced by this aluminum material is easy to roll when sealing, so the lock of the seal is flat and smooth, and it is not easy to wrinkle. Good fit on the mouth. At the same time, the hardness HV value of the aluminum cover is standardized by all production plants, and too low or too high can not meet the requirements of good sealing.

In addition, the wall thickness of the aluminum cover also has a greater impact on the sealing quality and pass rate. The general aluminum cover wall thickness standard is 0.2mm, and the variation range is preferably 0.18-0.22mm. The actual wall thickness of the domestic aluminum cover is 0.14-0.26mm. When the thin aluminum cover (especially the larger diameter aluminum cover) is sealed, it is easy to wrinkle. In order to achieve a better sealing effect, the gap between the aluminum cap and the mouth of the bottle should be slightly smaller, and the height of the aluminum cap should be correspondingly shorter.

2. The effect of the cooperation between the aluminum cap and the bottle mouth on the sealing quality

The sealing quality is most likely to be affected by the fit between the aluminum cap and the bottle mouth, including the radial fit tolerance and the axial (height direction) tolerance of the aluminum cap and bottle mouth. In the radial fit tolerance group, there are two fit sizes of the inner diameter D1 of the aluminum cap and the outer diameter D2 of the bottle mouth, and the fit clearance is generally 0.3mm-0.4mm. When the gap is too small, the "wearing cap" will be incorrect and the "wearing cap" will not appear on the blanking process; when the gap is too large, it will be easy to fall off the cap, the shape of the lock is not round, and the sealing Not tight, easy to loose and other phenomena. In addition, for the aluminum cover with thicker wall thickness (0.2-0.26mm), a larger fit gap can be selected appropriately.