In modern society, many people aren’t so familiar with aluminum foil. Comparing with fashion clothes, intelligent electrical apparatus, and delicious food, the aluminum foil seem no presence. But if you are care about your life, you will find it everywhere. Like flexible duct in kitchen, aluminized paper in BBQ, drug packaging, and aluminum foil container.etc. Beside, there are other application that you couldn’t see, like shielding aluminum foil in cable, conductive material in refrigerator.
The aluminum foil is widely used as cable shielding material in electron industry. Due to the good shielding & insulation and mechanical property. Although it’s a ideal item,
many quality problems may exist in the production process.
What quality problems may exist? What result will it lead？
Firstly, the most common quality problem is pinhole.
The dimension and quantity of pinhole will affect moisture resistance, gas resistance and light shading of aluminum foil laminating mylar materials. In international regulation, the pinhole requirements are relatively high. the thickness is more than 0.020mm with no pinhole. The thickness is less than 0.020mm with 0.1mm pinhole. Its diameter is usually about 0.15mm. What factors may cause pinholes?
1）Raw material
Usually, alloy 1xxx series with temper O is suitable for cable aluminum foil, because of the percentage of Fe and Si. The Fe and Si is controlled in reasonable range by heat treatment. What’s more, purifying the non-metallic particles and impurities to improve the purity of metal. These measures could reduce the quantity of pinhole in production process.
2）Manufacturing technique and machine.
The reliability of manufacturing technique have influence on the pinhole. For example, the rolling speed and back pull controlling, the roughness in roller surface, filtration precision of rolling oil, and heat treatment. Then, the full set machine with high precision and good stability play an important role.
3）The environment in workshop
As we know, different environment in workshop could create different product quality. When the environment of the production workshop is untidy, the dust or impurity may exist in raw material, semi-finished product, machine that we couldn’t see by eye. Under this situation, if the dust or impurity adhere to the roller, it might damage the roller and cause the aluminum to produce cyclical pinholes and bubbles. So keeping the plant clean according to 6S standard is so important and effective for the factory.
In summary, the pinhole could decide the mechanical property. In case of the elongation cannot reach the requirement, it’s possible to break during the aluminum laminating PET film process. Besides, crack edges and burrs will be found in slitting.
Once this faulty product is used to twine the conductive under high speed, the risk of breaking and even the significant economic loss may happen. Therefore, manufacturer should pay attention to the controlling of pinholes quantity.
Secondly, the aluminum foil is easy to corrode.
General, people confuse the corrosion with oxidation of aluminum foil. In fact, they are completely different. Oxidation means aluminum foil is oxidized to oxide, and form a oxide layer for 1/500um to protect base material. Corrosion means the aluminum foil is corroded by water or lye, the surface become white gray, that reduce the peel strength seriously. This quality problem often occur in transportation. The main reason is the packaging is not enough tight.
If the corroded aluminum foil is laminated with PET film, not only the the peel strength is low, but also the aluminum foil may separate with PET film. As a result, this laminated material is used in cable, the shielding will be bad.
Thirdly, remaining oil, oil spot and sticking is the common quality issues.
The machine oil mix in the rolling oil, or the stickiness of rolling oil is so strong, or
The wind in outlet of mill is too small to blow the oil may lead to these quality issues.
Each process may produce oil should be noted.
If people could prevent the remaining oil, oil spot and sticking from staying the surface of aluminum foil, the tensile strength and elongation would be improved.
Finally, Bright spots, scratches, cracked edges, burrs and bumps.
To control above defect, improving the quality of raw material is first. No cracks, scratches, metal and non-metal pressing in surface of raw material. Proper heat treatment, accurate hot rolling temperature, reasonable structure is good for the surface quality. Then, choose high quality rolling oil and additives, maintain the best physical and chemical indicators, and ensure that the surface quality of the roll is uniform without damage. Finally, people should pay attention to prevent surface damage in the cutting, transportation, stacking, packaging process.
The problem mentioned above covers most quality problems of aluminum foil. And we can learn they mainly occur in four parts: raw materials, equipment, production process, and packaging & transportation. You can view it as a large project, every process and rule must be strictly observed and operated to ensure high quality. After aluminum laminating the PET film, this laminated material has better tensile strength, elongation and excellent shielding insulation. One hand, good elongation covers and protects the conductor in the cable from being exposed, preventing leakage of electromagnetic waves. On the other hand, it can also prevent external electromagnetic waves from interfering with the signal in the cable. Unimpeded signal transmission is essential to modern society and life. It enables the information to share rapidly and accelerates the process of global integration. In addition, it also penetrates into every aspect of people’s life and brings a lot of convenience. Because of this, the safety and stability of wire and cable need to be concerned for long-term, the same as quality of aluminum foil.
