The aluminum sheet manufacturing process is a complex and delicate process involving multiple links. The whole manufacturing process including aspects of raw material preparation, smelting and casting, rolling processing, surface treatment, etc.

1. Raw material preparation
- Raw material selection: Mainly use aluminum ingots (purity is usually above 99%), add alloy elements (such as copper, magnesium, silicon, zinc, etc.) according to different uses to obtain the required mechanical properties and functional characteristics (such as 6061 aluminum sheet adds magnesium and silicon, suitable for construction and mechanical parts).
- Waste recycling: In order to reduce costs and protect the environment, waste aluminum sheets, aluminum products and other waste materials will be sorted and cleaned, and recycled through smelting, but the impurity content must be strictly controlled.

2. Smelting and casting
- Smelting process
Furnace heating: Put the aluminum ingots and alloy elements into a reverberatory furnace or electric furnace for heating, and the temperature is controlled at 700-800℃ to completely melt the raw materials.
Degassing and slag removal: Add refining agents (such as hexachloroethane and nitrogen) to remove hydrogen and oxide inclusions in the melt, and further purify the melt by standing or filtering (using ceramic filter plates) to avoid defects such as pores and cracks in subsequent processing.
- Casting process
Ingot preparation:
Continuous casting: The melt is cooled and solidified through a crystallizer to form a long strip of ingots, which is suitable for the production of large-size aluminum sheet billets with high efficiency and uniform structure.
Semi-continuous casting: The melt is injected into the mold and cooled while casting to form a cylindrical or rectangular ingot with high dimensional accuracy, which is often used in high-end aluminum sheet production.
Ingot processing: After the ingot is cooled, it is sawed and milled (to remove surface oxide scale and defects), and cut into suitable lengths and thicknesses according to subsequent rolling requirements.

3. Rolling processing
- Hot rolling
Heating the billet: Heat the ingot to 400-550℃ (adjust the temperature according to the alloy type) to give it good plasticity.
Rough rolling and finishing rolling: Multiple passes of rolling are performed on the hot rolling mill to gradually reduce the thickness (such as rolling from a 100mm thick ingot to a 10-20mm slab), while improving the metal's organizational structure and mechanical properties. During the hot rolling process, the rolling speed, reduction and cooling rate need to be controlled to avoid cracking or uneven performance of the aluminium sheet.
- Cold rolling
Room temperature rolling: After the hot-rolled slab is annealed (to eliminate internal stress and soften the structure), it is cold rolled at room temperature to further reduce the thickness (it can be rolled to foil below 0.1mm) and improve the surface accuracy and hardness of the plate (such as 5052 aluminum sheet can obtain higher strength through cold rolling).
Intermediate annealing: If there are many cold rolling passes, intermediate annealing is required during the rolling process to prevent the aluminum sheet from becoming brittle due to work hardening.
- Finishing treatment
Stretch and straighten: The wavy and sickle bend defects of the plate are eliminated by the stretch and straighten machine to improve the straightness.
Shearing and slitting: According to the size requirements, the plate is cut into rectangular sheets with a shearing machine, or cut into narrow strips with a slitting machine (for the production of aluminum strips and aluminum foil).
Surface cleaning: Remove oil and oxides on the surface of the plate by alkaline washing, acid washing or electrolytic cleaning to ensure the adhesion of subsequent surface treatment.

4. Heat treatment
- Annealing: Heat the aluminum sheet to a certain temperature (such as 200-400℃), keep it warm and slowly cool it to eliminate work hardening and restore plasticity. It is suitable for plates that require subsequent forming processing (such as aluminum sheets for cans).
- Solution treatment and aging:
Solution treatment: Heat the alloy aluminum sheet to a high temperature (such as 6063 aluminum alloy to 510-530℃) to fully dissolve the alloy elements in the aluminum matrix, and then quickly water cool it to obtain a supersaturated solid solution. At this time, the plate has low strength but good plasticity.
Aging treatment: The plate after solid solution is kept at room temperature (natural aging) or heated (artificial aging, such as 170-200℃) for a period of time to precipitate the strengthening phase, which significantly improves the strength and hardness of the plate (such as 7075 aluminum sheet is suitable for aerospace structural parts after aging).

5. Surface treatment
- Anodizing
Principle: The aluminum sheet is used as an anode and placed in an electrolyte such as sulfuric acid and chromic acid. A porous oxide film (usually 5-20μm thick) is formed on the surface through electrolytic reaction to improve corrosion resistance and wear resistance. At the same time, it can be dyed to obtain different colors (such as anodizing treatment is commonly used for aluminum sheets used in construction).
Sealing treatment: After oxidation, hot water or nickel salt solution is used to seal the pores of the oxide film to prevent pollutants from penetrating and enhance corrosion resistance.
- Coating treatment
Powder spraying: The powder coating is evenly sprayed on the surface of the aluminium sheet, and the powder is melted and solidified by high-temperature baking (180-220℃) to form a hard coating with rich colors and good weather resistance. It is suitable for building curtain walls and interior decoration.
Fluorocarbon spraying: Spraying with fluorocarbon coatings (such as PVDF) has excellent UV resistance, weather resistance and chemical corrosion resistance, and is often used in outdoor high-end architectural aluminum sheets.
- Electroplating and chemical plating
Electroplastic nickel, chromium, zinc and other metals on the surface of aluminium sheets, or forming an alloy layer through chemical plating to improve wear resistance, conductivity or aesthetics (such as nickel-plated aluminum sheets for electronic equipment housings).
- Other treatments
Wire drawing: Forming a filamentous texture on the surface of the aluminum sheet through mechanical friction to increase the aesthetics (such as furniture, electronic product sheets).
Polishing: Mechanical polishing or electrolytic polishing is used to make the surface of the aluminum sheet achieve a mirror effect, which is used in decorative occasions.

6. Quality inspection
- Dimension inspection: Use calipers and micrometers to measure the thickness, width and length of the plate to ensure that it meets the tolerance requirements.
- Surface quality inspection: Visually or with the help of instruments to detect whether the surface has scratches, bubbles, color difference, oxidation spots and other defects.
- Mechanical properties test: tensile strength, yield strength and elongation are measured by tensile test, and hardness (such as HB, HV) is tested by hardness tester to ensure that the performance of the plate meets the standard.
- Chemical composition analysis: The content of alloy elements is analyzed by spectrometer to prevent the composition deviation from affecting the performance.
- Nondestructive testing: Ultrasonic flaw detection and X-ray detection are performed on aluminum sheets for important purposes (such as aviation aluminum plates) to check for internal defects.

7. Finished product packaging and storage
- Packaging: Wrap the aluminum sheet with moisture-proof paper and plastic film to avoid moisture and scratches during transportation. For large-sized plates, wooden frames are required to fix them.
- Storage: Store in a dry and ventilated warehouse to avoid contact with corrosive substances such as acids and alkalis to prevent surface oxidation.

Typical application scenarios of aluminium sheet:
- Construction field: curtain wall sheets, ceilings, door and window frames (anodized or painted 3003, 6063 aluminum sheets).
- Transportation: automobile body sheets, high-speed rail carriage sheets (lightweight 5052, 6061 aluminum sheets), aircraft skins (high-strength 2024, 7075 aluminum sheets).
- Electronic equipment: mobile phone housings, heat sinks (high thermal conductivity 1060 pure aluminum sheets or 5052 aluminum sheets).
- Packaging: aluminum foil (used for food packaging and pharmaceutical packaging, made of cold-rolled foil).
- Mechanical manufacturing: molds, structural parts (requires high-strength 6061-T6, 7075-T6 aluminum sheets).

Process optimization and development trends
- Lightweight and high strength: Develop higher strength and lower density aluminum sheets (such as aluminum-lithium alloy sheets for aerospace) by optimizing alloy composition and rolling process.
- Green manufacturing: Promote environmentally friendly surface treatment processes (such as chromium-free passivation, water-based paint spraying) to reduce pollutant emissions.
- Intelligent production: Introduce automated rolling equipment and online detection systems to improve production accuracy and efficiency (such as AI visual detection of surface defects).
- Ultra-thin and high-precision: Cold rolling technology is developing towards thinner specifications (such as aluminum foil below 0.01mm) and higher dimensional accuracy to meet the needs of high-end fields such as electronics and optics.

Through the above manufacturing processes, aluminum sheets can be processed into products of various specifications and performances, which are widely used in multiple industries. The precision and technical level of its manufacturing process directly affect the quality and application range of the product.