Aluminum foil is a kind of aluminum rolling material. Aluminum foil is mainly used for thin and thick products. Generally, aluminum products with thickness less than 0.2mm are called aluminum foil in the industry. Generally, the edge is longitudinally cut and supplied in whole roll. Aluminum foil is a soft metal film, which is not only waterproof, airtight, light blocking, abrasion resistant, fragrant, non-toxic and tasteless, but also easy to process beautiful patterns and lines in many colors due to its elegant silver luster.
According to the thickness division, aluminum foil can be divided into double zero foil, single zero foil and thick foil. Double zero foil refers to the foil with two zeros behind the decimal point when its thickness is in mm (i.e. thickness<0.01mm); Similarly, single zero foil is a kind of foil with a zero behind the decimal point (0.01mm ≤ thickness<0.1mm) when the unit of quantity is mm; Thick foil refers to aluminum foil with thickness between 0.1mm and 0.2mm.
Generally speaking, the double zero foil is mainly used in food packaging materials, tobacco packaging, electronic device optical foil, etc; Single zero foil is used for some food packaging materials, drug packaging design, electronic circuit signal shielding, air conditioning foil, etc; Thick foil is mainly used for air conditioning foil, utensil foil, architectural decoration design and industrial main purposes.
Production process flow
The aluminum foil processing process is an aluminum product with more production processes, the least thickness and the most difficulty in the aluminum product processing industry. At present, there are two common production and processing processes in the industry: (1) casting and hot rolling; (2) Double roll casting method.
Casting hot rolling method
First, the aluminum solution is built into flat ingots, and then after homogenization, hot rolling, cold rolling, intermediate annealing and other processes, the aluminum solution is cold rolled into plates with a thickness of about 0.4~1.0 mm as foil billets (melting → hot rolling → cold rolling → foil rolling).
In the casting and hot rolling method, the hot rolled billet first removes the defects such as oxide film and impurities on the casting surface through milling, and then promotes the casting metallographic structure to be more uniform through homogenization. Then, the hot rolling, cold rolling, intermediate annealing and other multi process processing processes are carried out. After many times of reaction and work hardening, the internal structure uniformity and grain size of the billet have been significantly improved, Therefore, the hot rolled billet is generally of good quality and suitable for high-quality double zero aluminum foil and aluminum foil products for production and processing. However, hot rolled blanks in low alloy plates have many problems, such as high earing rate, easy cracking, uneven concave and convex deformation areas, which hinder the improvement of the yield of high-quality aluminum foil.
Twin roll casting
Compared with the casting and hot rolling process, the casting and rolling process is relatively simple; Instead of going through various technological processes such as smelting casting, milling, homogenization and hot rolling, the aluminum solution is directly poured into two rotary casting rolls (continuous casting mold), and the two whole processes of condensation and hot rolling are completed simultaneously in the casting and rolling area within 2~3s to obtain plates with a thickness of 4~7mm. Similar to the hot rolled aluminum foil billet, the cast rolled plate also needs to go through a series of cold rolling and intermediate quenching processes, and finally cold-rolled into a 0.3~0.7mm thick plate as the aluminum foil billet.
The twin roll casting method is simple in equipment, low in total investment, and short in production and manufacturing cycle time, which eliminates the complicated processes of milling, homogenization, hot rolling and other multiple procedures in the production of hot rolled plates. Therefore, the cost of aluminum foil billet produced by casting method is greatly reduced; However, due to the different heat dissipation methods and heat treatment conditions in the process of twin roll casting, the internal structure of the cast rolled plate mainly has the following shrinkage, uneven mechanism, and rough crystal mechanism after quenching. Its quality management is difficult, so it is seldom used in high-quality aluminum foil products.
At this stage, the process of roll casting used for aluminum foil billet is becoming more and more mature. More enterprises widely use roll casting process to manufacture aluminum foil, and roll casting has become the main process of aluminum foil. Cast rolling occurred in the 1970s, and its technology is still not mature.
In recent years, Dingsheng New Material has developed the "green manufacturing technology of casting rolling cold rolling short process" and successfully applied it to high-end brands such as double zero foil and driving force battery foil. This method realizes independent innovation in the industrial chain from the aspects of composition improvement, smelting process, continuous casting rolling process, cold rolling/foil rolling process improvement and performance test, and quality precision control technology. Casting rolling method is used to replace hot rolling method to produce aluminum foil/metal sheet for power lithium battery, which reduces the production cost of aluminum foil/metal sheet manufacturing enterprises for power lithium battery, It has improved the competitiveness and promoted the rapid development of China's rechargeable battery aluminum processing industry to a certain extent.
After being made into aluminum foil blanks, the aluminum foil blanks are rolled into aluminum foils of different thicknesses through a series of rough rolling, intermediate rolling and fine rolling, and then quenched for finished products. Generally speaking, thick foil only needs rough rolling, single zero foil needs rough rolling and vertical rolling, and double zero foil and other aluminum foil with high precision requirements need rough rolling, intermediate rolling and fine rolling.
As far as aluminum rolling enterprises are concerned, hot rolling routes are more frequently used. According to China Nonferrous Metals Report, by the end of 2018, China had more than 800 twin roll casting production lines with an annual production capacity of more than 8 million tons; There are more than 200 casting and hot rolling production lines, with a production capacity of about 20 million tons per year. By 2020, China's twin roll continuous casting and rolling strip production will exceed 8 million tons, and the casting and hot rolling strip production will exceed 42 million tons per year.
The selection of production process of rechargeable battery aluminum foil will also be different. Cast rolling is popular, such as Dingsheng New Material, Tianshan Aluminum, Wanshun New Material, etc; Some are hot-rolled, such as Huafeng Aluminum, Yongjie New Material, etc; In addition, the newly established production capacity of Zhongyuan New Material Co., Ltd. and Shenhuo Co., Ltd. has only been put into the foil rolling stage.
Statistical analysis of projects in the current construction of aluminum plate, strip and foil
Name of the company's project Time of production Capacity Total investment in commodities New production line arrangement Tianshan Aluminum's annual production capacity of 300000 ton rechargeable battery aluminum foil blank production line 2023 300000 ton rechargeable battery aluminum foil blank 800 million RMB casting rolling cold rolling foil rolling annual production of 200000 ton rechargeable battery aluminum foil fine rolling and splitting production line 200000 ton rechargeable battery aluminum foil fine rolling Carbon coated 2 billion yuan annual output 20000 ton rechargeable battery aluminum foil technology transformation 20000 ton rechargeable battery aluminum foil 100 million yuan Xinjiang Tianzhan New Material Ultra High Purity Aluminum Phase I and R&D Center Project 100000 ton ultra-high purity aluminum 500 million yuan annual output 50000 ton driving force battery electrode aluminum alloy profile foil new project December 2022 50000 ton driving force battery electrode Aluminium alloy profile foil with an annual output of 610 million yuan cast rolling cold rolling foil rolling 800000 tons of rechargeable battery and various blank new projects 2025 800000 tons of battery foil and various blank 3 billion yuan Mingtai Aluminum's annual output of 700000 tons of emerald green new aluminum alloy profile new projects 2022 March 700000 tons of power lithium battery material, rechargeable battery aluminum foil blank, 4.473 billion yuan (14) Hot continuous rolling aluminum plastic film blank, automobile plate blank, storage tank stock Mingsheng new materials such as tank cover materials in June 2021 500000 ton super hard 3C raw materials 200 million yuan Cold rolled Changlu Co., Ltd. 30000 ton power lithium battery special aluminum foil new project by the end of 2023 30000 ton power lithium battery aluminum foil 350 million foil rolling 100000 ton reconstituted aluminum plate, strip and foil new project by 2023 100000 ton reconstituted aluminum plate, strip and foil 220 million cast rolled Wanshun new material annual output 72000 ton high precision electronic devices Alumina industrialization project 40000 ton high precision electronic device aluminum foil 1.42 billion yuan foil rolling in August 2020 32000 ton high precision electronic device aluminum foil rolling in August 2023 130000 ton high precision aluminum plate and strip new project 130000 ton rechargeable battery aluminum foil blank 80000 ton in May 2023 Double zero aluminum foil 1.2 billion yuan, cast rolling cold rolled billet, plate roll 50000 tons, annual output 100000 tons, driving force and power battery foil new project 100000 tons, rechargeable battery aluminum foil 2.08 billion yuan, foil rolling 50000 tons, annual output 50000 tons, new energy technology, carbon coated foil new project 25000 tons, carbon coated foil 520 million yuan, paper making Sizing 25000 ton carbon coated foil Dongyang Guangguang's annual output of 100000 ton low-carbon environment-friendly high-grade rechargeable battery aluminum foil new project 202.35 million ton low-carbon environment-friendly high-grade rechargeable battery aluminum foil 2.71 billion yuan 202.55 million ton Zhongyuan new material annual output of 50000 ton battery foil new project 2024 25000 ton battery foil 350 million yuan foil rolling 25000 ton battery foil 350 million yuan Nanshan Aluminum has excellent performance High grade aluminum foil production line project October 2021 21000 ton performance excellent aluminum foil 450 million yuan foil gift lightweight aluminum strip production line technical transformation project 2021 100000 ton lightweight aluminum strip 1.56 billion yuan cold rolled lightweight aluminum alloy plate production line project 2024 200000 ton lightweight aluminum strip 2 billion yuan cold rolled Xinjiang Zhonghe performance excellent high-purity aluminum green manufacturing new project 2024 23000 tons of high-purity aluminum of 380 million yuan per year, loose shrinkage method, low-carbon emission reduction, green economy, and new aluminum based materials industrialization project 35000 tons of aluminum alloy profiles of 80 million yuan per year in 2023, emerald green high-purity high-precision electronic devices new materials project 16000 tons of high-performance electronic devices aluminum foil of 410 million yuan per year, foil rolling, 15 million square meters per year, high-performance high pressure foil forming new project June 1, 2020 , 5 million ㎡ chemical foil 625 million yuan annual output 15000 tons of three-layer high-purity aluminum purification and various processing plant projects 15000 tons of high-purity aluminum 490 million yuan annual output 3000 tons of high-strength and high toughness aluminum alloy profile large cross-section cast earth brick new project in 2023 3000 tons of high-strength and high toughness aluminum alloy profile large cross-section cast billet 160 million yuan annual output 500 tons of ultra-high purity aluminum base sputtering target billet New project: 500 tons of ultra-high purity aluminum based anti radiation target blank of 70 million yuan in 2023 Huafeng Aluminum's annual output of 150000 tons of high-grade aluminum plate, strip and foil for new energy vehicles New project: 150000 tons of high-grade aluminum plate, strip and foil of 1.98 billion yuan in 2025 Hot rolling and cold rolling of 200000 tons of aluminum plate, strip and foil New project: 200000 tons of aluminum plate, strip and foil of 1.99 billion yuan in 2021 Melting, hot rolling and cold rolling of Shenhuo Co., Ltd. Shenlong Baoding high-grade double zero aluminum New foil project July 2020 55000 ton double zero aluminum foil commodity 100000 ton RMB 3325 million foil rolling in the second half of 2023 50000 ton single zero aluminum foil commodity 5000 ton Li Dao new material power lithium battery collector fluid raw material new project By the end of 2023 battery grade aluminum foil 1 billion RMB carbon coated aluminum foil and continuous composite aluminum profile new project of aluminum profile deep processing industrial park December 2022 60000 The annual output of tonnage aluminum profile is 380 million yuan, and the annual output of Yongjie new material is 45000 tons, and the financing progress of high-precision aluminum plate, strip and foil technology transformation of 45000 tons of lithium ion battery aluminum foil is 740 million yuan, and the annual output of 100000 tons of lithium ion battery high-precision aluminum plate and strip technology transformation of 100000 tons of lithium ion battery high-precision aluminum plate and strip is 550 million yuan, and hot rolling
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