In the aluminum roofing sheet factory or the application process, sometimes there will be the above black spot situation, what is this situation? Let’s look at it. First of all, the aluminum roofing sheet materials, aluminum roofing sheet manufacturers produced by the aluminum roofing sheet cover is 0.5mm thick LF21 aluminum plate processing. This type of aluminum roofing sheet has many parts of the same material, similar shape and same process, but similar shape parts processed at the same time have no such failure. And it’s not the fault of a defective raw material. 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.

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