Aluminum foil is a kind of aluminum rolled material. Aluminum foil is mainly about thickness. In the industry, aluminum products with a thickness less than 0.2mm are usually called aluminum foil. The edges are usually cut vertically and delivered in rolls. Aluminum foil is a soft metal film. It not only has the advantages of moisture-proof, air-tight, light-shielding, abrasion resistance, fragrance retention, non-toxic and tasteless, but also because of its elegant silver-white luster, it is easy to process beautiful patterns and colors of various colors. pattern.
According to thickness, aluminum foil can be divided into double zero foil, single zero foil and thick foil. Double-zero foil refers to a foil that has two zeros after the decimal point when its thickness is measured in mm (i.e. thickness <0.01mm); similarly, single-zero foil refers to a foil that has one zero after the decimal point when its thickness is measured in mm. Foil (0.01mm≤thickness<0.1mm); thick foil refers to aluminum foil with a thickness between 0.1mm and 0.2mm.
Generally speaking, double zero foil is mainly used for food packaging, cigarette packaging, electronic optical foil, etc.; single zero foil is used for some food packaging, pharmaceutical packaging, electronic circuit signal shielding, air conditioning foil, etc.; thick foil is mainly used for air conditioning foil, Container foil, architectural decoration and industrial uses.
Production Process
The aluminum foil processing process is the aluminum product with the most processing steps, the smallest thickness, and the most difficulty in the aluminum processing industry. At present, there are two commonly used processing technology routes in the industry: (1) Ingot hot rolling method; (2) Double-roller casting and rolling method.
Ingot hot rolling method
First, the aluminum melt is cast into a flat ingot, and then after homogenization, hot rolling, cold rolling, intermediate annealing and other processes, it is continued to be cold rolled into a plate with a thickness of about 0.4~1.0 mm as a foil blank (casting → hot rolling) Billet→cold rolling→foil rolling).
In the ingot hot rolling method, the hot-rolled billet is first milled to remove defects such as the oxide layer and impurities on the surface of the ingot, and then the microstructure of the ingot is made more uniform through homogenization, and then hot rolling, cold rolling and intermediate After multiple processes such as annealing and recrystallization, the internal structural uniformity and grain size of the billet have been significantly improved. Therefore, hot-rolled billets are usually of better quality and are suitable for high-quality double-zero aluminum foil and deep processing. Aluminum foil products. However, hot-rolled blanks have problems such as high ear yield, easy cracking, and uneven deformation areas during the deep drawing process, which restricts the improvement of the yield of high-quality aluminum foil.
Two-roll casting method
Compared with the ingot hot-rolling method, the process flow of producing aluminum foil blanks by the cast-rolling method is relatively simple; there is no need to go through complex process steps such as ingot melting, milling, homogenization and hot rolling, but the aluminum melt is poured directly. Enter two rotating casting rollers (crystallizer), and complete the solidification and hot rolling processes simultaneously in the casting and rolling area within 2 to 3 seconds to obtain a plate with a thickness of 4 to 7 mm. Similar to hot-rolled aluminum foil billets, cast-rolled plates also need to go through a series of cold rolling and intermediate annealing processes, and are finally rolled into 0.3~0.7mm thick plates as aluminum foil billets.
