Although the roof water drainage channel is small, it is one of the most likely places for water accumulation on the vehicle body. The corrosion resistance is the key factor.
Why does it tend to have problems?
Common rollers are prone to scratching the galvanized layer or coating during the forming process;
If the forming angle is too large, the protective layer will be thinned, and rust will occur after several years.
Equipment details:
Use coating rollers or ceramic spraying technology to reduce the risk of zinc layer being scratched;
The pass design should allow the sheet to gradually transition instead of "pressing it all at once";
Add online detection to confirm that the surface of the finished product has no obvious scratches.