Analysis of the cause of black spots on the surface of aluminum plates.

Aluminum plate is divided into pure aluminum plate, alloy aluminum plate, thin aluminum plate, medium thickness aluminum plate pattern aluminum plate. Used on construction of the aluminum plate including single aluminum plate, aluminum sheet and so on the many kinds of composite materials, generally refers to the single aluminum plate, often used in building decoration engineering, single aluminum sheet used in aluminum sheet curtain wall in recent years is relatively rare. The reasons for the black spots on the surface of aluminum plates are analyzed.

aluminum plates
aluminum plates

The first is the material of aluminum plate, aluminum plate manufacturer produces the upper cover is the LF21 aluminium sheet that is made of 0.5mm thick. The aluminum plate of this model has a variety of materials, similar shapes, and the same process parts, and the same time processing of similar shape parts did not have such failures. And it is not a fault of raw materials. It’s on the processing technology, cover silver plating process for roughly: outgoing parts machining pretreatment ─ ─ ─ ─ galvanized zinc leaching plating copper electroplating silver ─ ─ painting 823 ─ ─ dip coating into the Treasury.

In the process of plating on aluminum plate, it is possible that some production link of electroplating has changed, resulting in failure. However, the investigation found that, in the condition that the production conditions did not change, similar parts of the same period did not have such failure. Therefore, the factors that change the conditions of electroplating production are excluded. According to the previous production experience, the most common reason for the discoloration of silverware is the influence of sulfur element on the silver coating.

In the past, the silver-plated parts have not been packaged and sealed in a timely manner, and the silver coating has been yellowed in the electroplating factory. However, after the fault parts are plated with silver, they are packed in time and stored in dry containers. This is not affected by the air atmosphere of the plant. In the process of spray painting, the paint was found to be processed by the upper cover, and the whole batch of repair records appeared. The most important reason is that the gap is not blocked, allowing the paint to enter and adhere to the surface of the silver coating and cannot be removed. In order to prevent the occurrence of such faults, it is suggested to seal the gap with 3M adhesive tape to prevent the penetration of paint fog.

In this way, the root of the problem is found, and measures should be taken to prevent the recurrence of hidden trouble, so that the surface of the aluminum plate is bright and new, and the factory rate is greatly improved.