The irregular small holes visible to the light on the surface of the aluminum foil are called pinholes. As the thickness decreases, the number of pinholes increases, which is one of the main defects of foil materials.

The dust in the billet, on the roll, in the rolling oil, and even in the air reaches a size of about 6 μm and enters the roll gap, which will cause pinholes. Therefore, it is impossible for 65m aluminum foil to have no pinholes. It can only be evaluated by how much and the size.

With the improvement of the installed capacity of aluminum foil equipment, the conditions of aluminum foil rolling are improved, especially the effective filtration of dust prevention and rolling oil and the setting of quick roll changing system, so that the number and size of pinholes in the aluminum box are increasingly dependent on The metallurgical quality and machining defects of the billet.

Since the pinhole is often the shedding of the blank defect, it is difficult to find the corresponding relationship with the original defect. It is generally believed that pinholes are mainly related to gas content, inclusions, compounds and component segregation.

Taking effective aluminum liquid purification, filtration, and grain refinement can help reduce pinholes.

Improving the hardening properties of the material, such as alloying, can also help reduce pinholes. The pinholes of 6μm aluminum foil rolled by high-quality aluminum pin blanks can be less than 100/m². In the aluminum foil rolling process, there are many other factors that cause pinholes, which can be catastrophic. Thousands of pinholes per square meter are not uncommon. Strengthen the filtration of rolling oil.

Short-term replacement of rolls and dust-proof measures are necessary conditions to reduce pinholes in aluminum foil; using large rolling force and small tension rolling will also help reduce pinholes.