How to Control Aluminum Foil Quality

1235 and 8011 aluminum foil roll are two popular choices with wide applications in battery, bottle sealing, food packaging, hair beauty, food container and pharmaceutical packaging. How to control their quality? It should start from the melt quality.

The melt quality can generally be measured by two indicators: the inclusion content in the solid structure and the hydrogen content in the liquid melt. When smelting aluminum and aluminum alloys, it is inevitable that the melt is polluted by hydrogen and inclusions. Their content in the aluminum melt is an important indicator to measure the quality of the melt.

Aluminum and its alloys show the characteristics of easy oxidation and gas absorption during the smelting process, which makes it easy to form gases and inclusions in the molten aluminum, resulting in a series of defects such as air channels, pinholes, and inclusions in the final product, resulting in the break of processing during rolling.

The non-metallic inclusions in molten aluminum are mainly metal oxide inclusions, part of which comes from the furnace charge, and most of them are formed by the reaction of aluminum and oxygen during the melting and casting process, among which the melting temperature, melting conditions, slag content in the furnace, the quality of the charge, the way of the converter, and the masonry conditions of the furnace all have an impact on the amount of inclusions in the melt. Aluminum reacts with O2, N2, CO2, CO, etc. in the furnace gas to form alumina impurities.

Charges include aluminum ingots, master alloys, additives, and scrap at various levels. Among them, the alumina content in the aluminum ingot fluctuates in the range of 0.2×10-4%~2×10-4%. Others such as slag and waste have a large amount of oxidized inclusions, especially waste contaminated by oil and soil, which greatly increases the content of hydrogen and inclusions in the melt. Therefore, the purity of the charge itself is low, and the composition of the charge must be strictly controlled to produce high-quality 1235 aluminum foil.

The aluminum ingots put into production must be stored in a dry and clean environment, and it is strictly forbidden to join the production of wet ingots. The proportion of waste should be strictly controlled and must be less than 20%. Oily waste, tertiary waste and sorted out aluminum-containing slag cannot be added to the furnace for producing 1235 aluminum foil blanks. The order of feeding should be in accordance with the order in which the waste is added first and then the aluminum ingots are added to prevent the burning of the waste from causing oxidation inclusions.

In actual production, regular heat cleaning must be carried out, and the heat cleaning of the smelting furnace and holding furnace must be maintained at least once a week. Use specific tools to clean the slag on the surface of the furnace group and remove it from the furnace body. Moreover, the furnace group must be thoroughly cooled once a year to completely remove the slag accumulation in the furnace group and create a good environment for smelting production.