How aluminum foil is produced. Aluminum foil was first replaced by tin foil in 1910, when the first aluminum foil rolling mill was opened by Dr. Lauber to package chocolate in Switzerland.
To better understand how aluminum foil is produced. We have to start with its raw material, aluminum ingots.
Aluminum ingots are the raw material for the production of aluminum foil and sheets and all other aluminum parts, including car cylinders, etc. Production of aluminum ingots starts with the method of extracting alumina from bauxite mineral soil. The molten alumina is then decomposed in the presence of heat using the electrolysis phenomenon. In one of the electrodes, molten aluminum with a purity of more than 99.5% is extracted and molded. The product obtained is the same as aluminum ingots.
Convert sheet to foil:
It is produced in one of the following two methods: 6 mm thick aluminum sheet:
1- Strip casting: The passage of aluminum melt over ceramic plates between two rollers with a diameter of more than 80 cm shines. Cooling of the melt when passing under high pressure two rollers and turning it into a sheet with a thickness of 6 mm
2- Hot rolling: conversion of molten from ingots to aluminum slabs in different dimensions. For example, dimensions 3 meters – 30 cm – 120 cm. And heating slabs up to 500 degrees and using hot rolling. By sequencing in the rolling operation, it reaches a thickness of 30 cm to 6 mm and is rolled as an aluminum coil.
After obtaining the 6 mm aluminum sheet, the rolls obtained by cold rolling operation now reach a thickness of 0.5 mm. Then, using aluminum foil rolling machines, this thickness is reduced to less than 0.2 mm. From this thickness down is called foil product.
In such a way that by performing different steps of rolling aluminum sheet is obtained. Then, with the sequence of rolling process and heat treatment, the thickness is reduced and leads to the product of aluminum foil.
To maintain a constant thickness in the production of aluminum foil, beta radiation is transmitted through the foil to a sensor on the other side. If the intensity is too high, the rollers are adjusted. Increase the thickness. If the intensity is too low and the foil is too thick. The rollers apply more pressure, causing the foil to become thinner.
For thicknesses below 0.025 mm, the two layers are usually stacked on top for the final rolling. They are separated after rolling. Which produces foil with a light side and a matte side. The two sides are in contact with each other. The two outer sides become shiny. This is done to reduce rupture, increase production and control thickness.
Some lubrication is required during the rolling process. Otherwise, the foil surface will be damaged. These lubricants are sprayed on the foil surface before passing through the rolling rolls.
Aluminum foil hardens during the cold rolling process and is heat treated for most purposes. The foil rolls are heated until they reach a soft degree. Which may be up to 340 degrees Celsius for 10 hours. During this heating, the lubricating oils are burned and the surface dries.
