The exterior of the communication cable needs to be wrapped with a layer of aluminum foil for protection and shielding. This kind of aluminum foil large rolls are usually made of 1145 grade industrial pure aluminum. After continuous casting and rolling, cold rolling, slitting and complete annealing, it is divided into small rolls according to the length required by the user and supplied to the cable foil compounding factory.
Cable aluminum foil is made by attaching a special plastic film (0.058mm thick) on the upper and lower surfaces of the 0.15-0.20mm thick aluminum foil. The surface quality of aluminum foil is the most important factor affecting the peel strength, and its main surface quality problems are oil spots, corrosion, peroxidation, etc.
Oil spots are the most common quality problems on the surface of aluminum foil. The main reason is that the rolling oil is mixed with machine oil or the rolling oil has a high kinematic viscosity. In addition, the angle of the air nozzle at the exit of the rolling mill is incorrect, or the air pressure is too small.
The solution is: a. prevent the oil from mixing into the rolling oil; b. control the kinematic viscosity of the rolling oil, and it should not exceed 2.34×10 m2/s; c. heat the rolling oil in cold weather; d. control the amount of additives within 5 % to 7%; e. Add two rows of air nozzles at the exit of the rolling mill, 2 nozzles in the upper row and 4 nozzles in the lower row, blowing from the middle to both sides; d. Manually wipe off the oil on the surface of the aluminum foil in the last rolling pass; f. When the aluminum foil is annealed, stay at 200°C for a period of time to allow the rolling oil to fully evaporate.
Many people confuse the corrosion and oxidation of aluminum foil. In fact, the two are completely different. Corrosion is the loss of electrons by aluminum atoms to form white powder, and the product has no protective effect on the substrate; oxidation is the synthesis of oxides by aluminum atoms and oxidation, and the product has a protective effect on the aluminum substrate. Aluminum will form a layer of oxide film about 1/500 micron in nature to protect itself. After the aluminum foil is corroded, the white ash formed on the surface will seriously reduce the peel strength of the plastic-coated foil. The corrosion of the aluminum foil is caused by water or lye.
Aluminum foil being wet by rain during transportation is a common cause of corrosion. Another neglected is caused by fog. When the aluminum foil jumbo roll s transported for a long distance at night at high temperature, one side of the aluminum coil is cooled quickly, and the other side is at high temperature.
The mist in the cooling place condenses on it and penetrates into the aluminum coil. After it is transported to the customer's warehouse, the high temperature side heats the low temperature side, causing the aluminum coil to corrode.
The solution is that the 1000 ft roll aluminum foil should be tightly packaged to prevent rain and aluminum coils in high temperature state should not be packaged and transported.
A layer of oxide film naturally formed on the surface of aluminum has a protective effect, but if it is cooled by strong wind at high temperature, it will inevitably cause peroxidation and surface discoloration.
Overoxidized aluminum foil also reduces the peel strength of the cable foil. The prevention method is that after the aluminum foil is annealed out of the furnace, it cannot be cooled by strong wind, and it is allowed to cool slowly. If you need aluminum foil roll for cable foil compounding, welcome to contact us directly.