How to make foil?
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Foil is a very thin sheet made of any metal or metal alloy. The thickness of the foil, as a rule, does not exceed 0.2 cm, therefore it is comparable with the thickness of the paper sheet. Often, the foil is made from tin and its alloys (such foil is called “Staniel”), iron (the second name of the thick iron foil is “tin”) and gold (thinly rolled gold is called “tinsel”). The most common material used for the production of foil is aluminum. It is thin aluminum sheets in everyday life and it is called simply foil. How to make aluminum foil, read in this article.
Aluminum foil production technology
- Aluminum is smelted from aluminum ore (bauxite or alunite) at a metallurgical plant.
- The finished aluminum is poured into special forms and immersed in water for a quick cooling.
- The resulting large aluminum ingots (the length of the blanks is over 4 meters, and they weigh more than seven tons) are removed from the molds and transferred by crane to the rolling mill.
- An aluminum ingot is first prepared for rolling.To do this, the disc is placed on a special platform and, under the control of a computer, is cut off from all sides. With each side of the ingot, a three-millimeter upper layer is cut off with special equipment. As a result of this operation, all irregularities and pollution are removed from the workpiece and it takes the form of a regular parallelepiped with mirror-smooth sides.
- Next, the workpiece is heated to a temperature of 550 ° C and begin to roll it between the rollers. In order to prevent aluminum from sticking to the rollers, their surface is constantly wetted with a water-oil emulsion.
- The workpiece is passed through the rolls many times, with each pass, the thickness of the workpiece decreases. When it reaches a thickness of one centimeter, and this happens, as a rule, after sixteen times hire, the future foil is cooled and wound into a large roll.
- Then this roll is moved to the cold rolling mill, where the thickness of the workpiece is adjusted to 200 microns by cold pressing. If you want to get a thick aluminum foil, then the workpiece is passed through the rolls several times and the cold rolling process is stopped.
- If you need a thinner foil (such that we usually use for domestic purposes), the foil is passed through the rolls at least four more times.And the last time the foil becomes quite thin, so in order for it not to tear when passing through the rolls, the two foil strips are folded and passed through the rolls at the same time. It is because of this that the kitchen foil has two different sides - matte and glossy. The matte side is the side of the tape that was inside the workpiece, and the glossy side was outside, it was she who was in contact with the surface of the shaft and polished about it to a mirror finish.
- At the end of the production, irregular edges are cut off the foil sheets, the foil is cut into strips of the desired width, pieces of the required length are cut from strips, wound them onto cardboard tubes and the finished foil rolls are wrapped in film or cardboard boxes.