What Are Requirements for Aluminum Bottle Cap Material?

The alloys for aluminum sheet for caps include 1xxx series, 3xxx series, 5xxx series, 8011 aluminum alloy, etc. 1xxx series such as 1060 and 1070 are pure aluminum, with high aluminum content, relatively simple production process, affordable price, certain corrosion resistance and good processing performance, suitable for ordinary bottle caps with low strength requirements.

3xxx series, such as 3003 and 3105 aluminum alloys, have outstanding anti-rust properties due to the addition of manganese. Among them, 3105 aluminum alloy has good deep drawing processing performance, certain tensile strength and yield strength, low earing rate, easy processing, and is widely used in wine bottle caps and other fields.

Among 5xxx series, 5052 aluminum alloy is a typical one. After adding magnesium, it has medium strength, good corrosion resistance, weldability and cold working properties. After coating, the surface is bright and is often used for can lids and basic lids of functional beverages.

8011 aluminum alloy is often used for pharmaceutical packaging-grade bottle caps. The aluminum caps made of it are thin and easy to open. When selecting materials, it is necessary to accurately select the appropriate alloy material based on the specific use of the bottle cap, cost budget, performance requirements, etc.

Coating treatment requirements

Coating treatment is crucial for aluminum bottle caps. On the one hand, it can enhance the protective performance of the bottle caps. Coating on both sides of the coil substrate can improve the wear resistance of the bottle caps, making it less likely to be damaged by friction during production, transportation and use; at the same time, it greatly enhances the anti-rust ability, especially for some product packaging that needs to be stored for a long time or used in a humid environment, the anti-rust coating can effectively extend the service life of the bottle caps.

On the other hand, the coating helps to improve the aesthetics and printing adaptability of the bottle caps. The flat and smooth coating surface can make the subsequent printed patterns and texts clearer and more beautiful, and improve the overall image of the product. Moreover, for different application scenarios, such as food and beverage bottle caps, the coating must meet food-grade safety standards to ensure that there is no contamination of the contents.

Requirements for production process links

During the rolling process, the cold rolling process must strictly control parameters such as the number of rolling passes and the amount of reduction. For example, when producing certain bottle cap materials, multiple cold rolling passes may be required to gradually adjust the thickness of the plate to the specified size while ensuring the flatness and shape accuracy of the plate. In addition, the entire production process must ensure a clean environment to avoid the mixing of impurities, so as to avoid defects such as sand holes and pores on the surface of the bottle cap during subsequent processing.

Finished product performance requirements

The finished aluminum bottle cap material must have excellent properties in many aspects. In terms of mechanical properties, it must have appropriate strength and elongation. Insufficient strength will easily break during deep drawing; insufficient elongation will easily produce creases during processing. For example, bottle caps used for carbonated beverages must have sufficient strength to withstand internal pressure and prevent explosion.

In terms of dimensional accuracy, strict requirements are placed on dimensional deviations such as thickness and width. The general thickness is 0.20mm - 0.23mm, the width is 449mm - 796mm, and the thickness tolerance is controlled at ±0.1%. Accurate dimensions can ensure a good match between the bottle cap and the bottle mouth, achieving reliable sealing performance.

In terms of appearance quality, the aluminum sealing sheet surface must be flat, without rolling marks, scratches, stains and other defects, so as to ensure the subsequent printing effect and the aesthetics of the product. Moreover, for bottle caps with special requirements, such as bottle caps that are resistant to high-temperature boiling and sterilization, the material must be able to maintain stable performance under high temperature and high pressure environments without deformation, cracking and other problems.

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