What is the processing work before the aluminum is rolled

First of all, you may wish to use hot water to wash the aluminum coil. The hot water washing master should wash the degreaser remaining on the surface of the substrate to ensure that these residues can be dissolved in order to prevent these degreaser from forming secondary pollution to the substrate. The way of use is mostly the way of dipping and spraying. The hardness of the water used should not be very high, otherwise, the minerals in the water will generate ore spots on the surface of the substrate.


Secondly, the hot alkali degreasing because the pre-coated line speed is faster, so the degreasing agent used is usually a higher concentration, typical degreasing agent contains sodium hydroxide (NaOH), sodium carbonate (Na2Co3), water glass (Na2SiO3), phosphate and other components. The hot alkali degreasing process is usually handled in two steps to ensure that the surface of the aluminum coil substrate is washed clean, and is often washed by spray.


Again, it is passivated. Passivation treatment is to make passivation agent form conversion film on the surface of the substrate by means of pressure spray, dip coating or roll coating. Usually the method of pressurized spray is used, and the mud that occurs in the process of passivation liquid will often jam the spray hole, thus affecting the spray efficiency. Although the method of dipping solves this problem, the amount of passivation liquid is large. The above two methods need to clean the passivation liquid with water in the essential operation, and the problem of wastewater recovery and purification will occur. Roll coating is a good passivation construction method, which has the advantages of average coating, economic application, and no need for washing. Aluminum plate is usually selected chromate/oxide type treatment agent, which contains chromate, chromic acid, phosphoric acid and the catalyst fluoride and molybdate. This type of treatment agent must be added with phosphoric acid, otherwise it cannot be used to treat aluminum plates for food and beverages.