Knowledge

Many problems might rise in the aluminium foil production process, among which are thickness difference, water marks and oil remains. Here we deal with the three.

The thickness difference of aluminum foil rolls is often encountered in the rolling process of aluminum foil production. 3% thickness difference may be easy to achieve in aluminum plate manufacturing, but it is very difficult in aluminum foil production. Because the thickness of aluminum foil is very thin, such as drug foil, i.e. medical aluminum foil, the thickness is usually 0.02mm-0.025mm, many fine conditions will have a serious impact on it. Such as temperature, oil film, oil and gas concentration, etc. The length of a roll of aluminum foil can reach tens of thousands of meters, the rolling time is long, and it is easy to cause the uneven thickness. The only way to adjust the thickness is the tension speed. Therefore, it is very difficult to control the thickness difference of aluminum foil within 3%, and the requirements for equipment and environment are very strict.

A water mark refers to the water drop on the aluminium foil food before rolling. After rolling, some white spots will be formed. If the water mark is slight, it will affect the appearance and brightness of the aluminum foil surface. If it is serious, it may cause the ribbon of the aluminum foil. The first section of water mark is caused by the water drop in the rolling mill on the surface of aluminum foil or the water drop in the oil is formed in the rolling process. It is necessary to control the water content in the oil and keep the rolling mill clean and sanitary to avoid the water mark of food aluminum foil.

Oil remains are often encountered in the rolling step of aluminum foil production process, which means that there are some extra oil in the aluminum foil food after rolling, that is, oil other than rolling oil film. This kind of oil is complex and dirty. It is usually dripped on the surface of the aluminum sheet by the oil at the roll neck or at the outlet of the rolling mill. Oil pollution has a great impact on the quality of aluminum foil. Some aluminum is used as packaging or decoration materials, and the surface must be smooth and bright. Oil pollution will also affect the thickness of the finished aluminum foil roll. In the annealing process, it is easy to form bubble like bulge, and the oil pollution is relatively dirty, which will form a lot of residues and affect the use of aluminum foil. Oil pollution is a very important index to evaluate the quality of aluminum foil.