Smila aluminum foil, aluminum tape, strip, copper foil, copper tape, strip, sheets
Aluminum foil is one type of flat rolled aluminum. The thickness of aluminum foil is 5 to 150 micrometers (0.005 to 0.15 millimeters). Flat rolled aluminum with a thickness of more than 0.15 mm - these are already tapes, sheets and plates.
How aluminum foil is made
Aluminum foil is made in four main steps:
hot rolling of aluminum strip;
cold rolling of aluminum strip;
cold rolling foil;
cutting and rewinding foil into rolls for consumers.
Hot rolling of aluminum strip from slabs
The usual technology for the production of flat rolled aluminum - sheets, strips and foils - begins with the casting of molten aluminum into large rectangular aluminum ingots in the shape of a trapezoid - aluminum slabs - weighing from 10 to 25 tons and up to 10 m long. This takes place in special vertical semi-continuous casting machines actions.
Slabs are pre-annealed at a temperature of 350-450 ºС and then subjected to hot rolling into strips in rolling mills - single-stand or tandem - into strips with a thickness of 6 to 2.5 mm and wound into rolls at a temperature of about 300 ºС
Continuous casting and rolling of aluminum strip
More economical in terms of energy costs is the technology of direct continuous casting of molten aluminum into a strip with a thickness of 12 to 20 mm and continuous hot rolling on a tandem rolling mill. However, the application of this process is limited to a small number of aluminum alloys, which are not subject to the segregation of alloying elements during the rapid cooling that occurs during continuous casting. These alloys primarily include all grades of unalloyed aluminum.
The third - the most economical - method is the casting of a strip with a strip thickness of 6 to 3 mm at the exit directly from the aluminum melt between two rolls of two-roll casting units (Figure 2). The disadvantage of this method is rather low productivity.
This casting method is also only suitable for pure aluminum or low-alloy aluminum alloys.
All three of these methods of producing hot rolled aluminum strip have their own advantages and disadvantages in terms of strip material quality, productivity, energy consumption and labor requirements. Therefore, investment volumes and equipment maintenance costs are key factors in choosing the optimal solution for each specific manufacturer.
Cold rolling aluminum strip
After the end of the hot rolling step, the cold rolling step of the strip begins.
The process of cold rolling of aluminum strips can be carried out in various types of rolling mills. For small coils weighing up to 5 tons, single-stand reversing rolling mills are often used.
To work with coils weighing from 10 to 15 tons, non-reversible single rolling stands are usually used.
For large coils - over 25 tons - and for large production volumes, multi-stand tandem rolling mills are used
Although the rolling of the strips at this stage is called “cold rolling”, during each pass the strip is heated to about 100 °C. Therefore, it is required to apply a large amount of cooling water-oil emulsion to the rollers in order to maintain the thermal equilibrium of the process. After every three or four passes, the rolls are cooled to room temperature over several hours.
Work hardening of the material
During each pass through the rolling mill, the material of the aluminum strip is subjected to significant plastic deformation and therefore receives a strain hardening - work hardening, which is also called work hardening. The technological process of cold rolling includes one or two annealings to recrystallize the grain structure of the strip material. The degree of influence of cold rolling on the grain structure of the material depends on the chemical composition of the grade of aluminum or aluminum alloy used.
Rolling thin aluminum strip
The final rolling operation for almost all types of aluminum flat products is processing on non-reversing single-stand rolling mills. At this stage, a thin strip is obtained, which is used not only for further production of foil, but also, in particular, for the production of aluminum cans for drinks, including aluminum beer cans. This thin belt requires tight tolerances in thickness and flatness. In addition to beer cans, lithographic plates are also made from thin aluminum tape, which require an increased quality of its surface.
Rolling aluminum foil
The technology of rolling aluminum foil requires special precision in setting the gaps between the rolls and the parameters of the foil tension. All foil rolling mills are equipped with special tools to meet the stringent quality requirements.
On the last pass, the foil is rolled in two layers. To do this, on the penultimate pass, it is folded in half, and after the last pass, it is again strippedare laid and wound into two separate bays. That is why the finished foil has one side, the outer one during rolling, is shiny, and the other, the inner one, is matte.
Cutting and rewinding aluminum foil
The last step in foil production is cutting wide and large rolls of foil and rewinding them into rolls of various sizes and volumes - such as are needed by industrial processors or end users.
Alloys for aluminum foil
The main alloys for the production of aluminum foil are:
grades of technical aluminum: 1100, 1145, 1050, 1235;
low-alloy alloys of the Al-Mn series: 3003 and 3102;
Al-Si-Fe alloys with a high iron content: 8006, 8011, 8011A, 8111, 8079.
It seems that the only 7xxx series aluminum alloy that foil is made from is 7072. This alloy has a nominal zinc content of only 1.0% with a copper content of no more than 0.10%. This foil is used for the manufacture of automotive radiators. Alloy 7072 fins are mounted on a tube, such as Alloy 3003, which carries the coolant and provides it with cathodic protection against corrosion.
Iron in aluminum foil
Thin aluminum foil (6 µm) is the lightest "absolute barrier" for liquid packaging when mounted on a paper or plastic base. At the very beginning of the commercial use of the foil, it was made of pure primary aluminum Al 99.5 (1050), which came directly from the electrolysis of aluminum, as well as technical grade aluminum 1200 with a slightly higher iron content. 8xxx series high iron foil alloys have been introduced to improve foil strength in finished products.
Traditional foil aluminum "alloys" - aluminum grades 1050 and 1200 contain iron and silicon, which are the main impurities for them in an amount of 0.1 to 0.4%. These technical aluminum grades have a relatively low level of strength properties compared to other non-hardenable aluminum alloys, such as those alloyed with magnesium and manganese. Only 0.05% of iron can dissolve in aluminum near the melting point, and much less in solid solution at room temperature. The influence of iron is based on the following [2]:
interaction with dislocations, which gives an increase in strength properties;
suppression of grain growth and creation of recrystallization centers.
Figure 6 shows the strengthening effect of iron on strength properties, as well as a significant increase in formability (relative elongation). Figure 7 shows the grain structure after final annealing of alloys with different iron content.
With an increase in the iron content, grain refinement occurs, which explains the favorable effect of iron on the ability of the foil to form. The high content of iron in the foil somewhat complicates its subsequent remelting - recycling. The increased content of iron in aluminum foil can cause iron contamination of other aluminum alloys in which its content is limited.
Foil as rolling is a kind of ordinary sheet, however, it should be understood as much thinner sheets, or strips of rolled metals or metal alloys, characterized by very small dimensions in thickness, from about 0.015 to 0.25 mm, depending on the purpose and the method of manufacture used .
In life, we often meet aluminum foil, which we irreplaceably use in everyday life. But, this is not the only existing type of foil, there is also technical aluminum, lead, copper. Each of them has found its own scope depending on the characteristics. For example, lead foil is more often used for tobacco packaging, appliance parts, technical aluminum foil for thermal or waterproofing. This article will focus on copper foil, its production methods and applications.
As a material, copper has been used by people since antiquity. It is found in nature in the form of nuggets, which does not make its extraction very difficult. The use of copper for industrial purposes is characterized by its high ductility, electrical conductivity, thermal conductivity, corrosion resistance, which makes it an indispensable material in the electrical industry. Copper is used to make refrigerator parts, electrical wires, and even works of art.
If we talk about industries in which copper foil is used, then we can notice their diversity. This includes instrumentation, the food industry, and the chemical industry. For example, foil is used to make circuits, heating films for aircraft, cables, antennas, and much more, since the characteristics of the metal make it possible to use the thinnest copper tape in many industries. Also, it is used in residential and industrial construction, without losing its qualities throughout the entire period of operation.
Due to the popularity of this metal, there are a huge number of companies leading it.childbirth. But, it should be noted that more often the manufacturer adds too many impurities, resulting in a low-quality product. Therefore, when buying copper products, it is necessary to familiarize yourself with the activities of the supplier, his work experience. One of the most popular copper suppliers is the MetPromStar company, which has been selling rolled copper, non-ferrous metals and stainless steel for more than 10 years, with regional offices throughout Russia.
Speaking of copper foil, it is necessary to touch on the method of its production. There are several types of copper foil. According to the type of production, it can be rolled and electrodeposited. Accordingly, they are created on different equipment, differ in manufacturing methods.
Electrodeposited happens:
1) standard,
2) with high ductility,
3) hot drawn,
4) annealed.
The first type is more often used under the base and is rarely used in its pure form, due to poor flexibility. The other three types differ in the heat treatment of the standard foil, changing its ductility.
Rolled foil is divided into:
1) rolled,
2) low-viscosity cold-rolled,
3) rolled annealed,
4) rolled at low temperature.
For example, with cold metal rolling, the metal is heated a little so that it is ductile, yielding to pressure, and then it rolls between two wolves to the desired thickness.
Due to the method used, the foil can have different strengths and prices.
Such external characteristics of copper foil as a red tint, glossy, shiny look have found a new scope for its application - interior design, for example, the creation of decorative stained-glass windows on transparent glass. According to this type of use, another type of foil is distinguished - self-adhesive copper foil. It is called self-adhesive, because it is not necessary to apply glue to its surface. But even to buy it, you must know what you are using it for, since it differs in thickness and operating conditions.
copper foil is the thinnest copper used in industry. However, do not rush to say that you have seen and know it, and also constantly use it. The fact is that food foil, so popular in the household, is most often made of aluminum or steel, but not copper. As far as copper foil is concerned, it can be produced in two ways - the result is either rolled or electrodeposited foil. In the second case, the material turns out to be grainy, so it cannot be used dynamically - such foil is used only for static purposes. As for katana, this foil is much more even, so its dynamic use does not threaten the appearance of cracks. Characteristics of copper foil Copper foil, as mentioned earlier, has all the same properties and characteristics as the previous material options, but differs in its incredibly thin thickness. If it seemed to you that the copper tape is very thin, then you were wrong - in fact, the foil is the thinnest one. With certain processing methods, it is possible to achieve an amazing thickness of only 18 micrometers, and in some cases the result is even more impressive. But how can such a thin material be used? Application of copper foil Naturally, due to its electrical conductivity and incredibly thin thickness, copper foil is very often used in electrical engineering. It can be found in various electronic boards, even the tiniest ones. It is also very common to see copper foil being used for cable shielding, a task far superior to any other material available at the same price point. As mentioned earlier, copper foil is not used in the food industry, as it has much more suitable aluminum and steel alternatives. You can also find copper foil in the construction industry - most often there it is used for thermal insulation. And of course, very often not only copper, but also any other foil is used in printing in order to produce embossing. Naturally, these are not all areas in which such a wonderful product as copper foil can be used. Many thousands of years ago, when there was a copper age on Earth, people did not know how to handle other metals, so they used a simple and common material - copper. For all its shortcomings, it was much better at making and using tools than the stone that was previously used.
