Aluminum foil is made from an aluminum alloy containing 92% to 99% aluminum. Available in a variety of thicknesses, widths and strengths. Widely used in the manufacture of insulation for the construction industry, fins for air conditioners, electrical coils for transformers, capacitors for radios and televisions, insulation for storage tanks, decorative products as well as foil containers and various packaging applications. The popularity of aluminum foil in so many applications is due to several key advantages, one of the important ones being the availability of raw materials for its manufacture. Aluminum foil is inexpensive, durable, non-toxic, and oil-resistant. In addition, it resists chemical attack and provides excellent electrical and non-magnetic shielding.
Once the foil stock is made, it must be reduced in thickness to make the foil. This is done in a rolling mill where the material passes multiple times through metal rolls called work rolls. As the aluminum sheets pass through the rolls, they are extruded thinner and extruded through the gap between the rolls. The work rolls are paired with heavier rolls called backup rolls, which apply pressure to help keep the work rolls stable. This helps keep product dimensions within tolerance. The work and backup rolls rotate in opposite directions. Lubricants are added to facilitate the rolling process. During this rolling process, aluminum must sometimes be annealed (heat treated) to maintain its machinability.
The reduction of aluminum foil is controlled by adjusting the rotation speed of the roller and the viscosity, quantity and temperature of the rolling lubricant. The roll gap determines the thickness and length of the foil leaving the rolling mill. This gap can be adjusted by raising or lowering the upper work roll. Rolling on the foil yields two natural finishes, bright and matte. When the foil comes into contact with the work roll surface, a shiny finish is produced. To produce a matte finish, two sheets must be wrapped together and rolled at the same time; when this is done, the sides that touch each other end up with a matte finish. Other methods of mechanical finishing, usually produced during converting operations, can be used to produce certain patterns.
As the foil passes through the rollers, it is trimmed and cut with circular or razor-like knives mounted on roller mills. Trimming refers to the edges of the foil, while slitting involves cutting the foil into pieces. These steps are used to produce narrower crimp widths, to trim the edges of coated or laminated materials, and to produce rectangular pieces. For certain fabrication and converting operations, webs broken during rolling must be rejoined or spliced. Common types of splices used to join flat foil or back foil webs include ultrasonic, heat seal tape, pressure seal tape and electric welding. Ultrasonic joints use solid state welding in overlapping metals.
In many applications, industrial aluminum foil is used in combination with other materials. It can be coated with a variety of materials such as polymers and resins for decorative, protective or heat sealing purposes. It can be laminated to paper, cardboard and plastic film. It can also be cut, formed into any shape, printed, embossed, cut into strips, sheeted, etched and anodized. Once the aluminum foil is in its final state, it is packaged accordingly and shipped to the customer.
In addition to the process control of parameters such as temperature and time, the finished industrial aluminum foil must meet certain requirements. For example, it has been found that different conversion processes and end uses require different degrees of foil surface drying to achieve satisfactory performance. Wettability tests are used to determine dryness.
Other important properties are thickness and tensile strength. Thickness is determined by weighing a sample and measuring its area, then dividing the weight by the product of the area times the density of the alloy. Tension testing of foils must be carefully controlled, as test results can be affected by rough edges, small imperfections, and other variables. Place the specimen in the grips and apply pull or tension until the specimen breaks. Measure the force or strength required to break a sample.
Aluminum foil seal bags are popular in medical and retail food applications. The popularity of aluminum foil, especially for flexible packaging, will continue to grow. Aluminum foil packaging is widely used in takeaway packaging boxes, baked food packaging and other fields. The popularity of microwave ovens has led to the emergence of various forms of aluminum-based semi-rigid containers that are designed specifically for these ovens.
Lichenalu is a trusted and experienced bulk aluminum foil manufacturer with a proven track record of providing high-quality products to customers worldwide. Whether you're looking for aluminum foil for packaging, insulation, or cooking, Lichenalu has the expertise and capabilities to meet your needs. Don't hesitate to make enquiries today and learn how Lichenalu can help you with your aluminum foil requirements.
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