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Evidence of Improved Corrosion Resistance after Laser Marking

I am currently dealing in a project that's proposing laser marking on coated aluminum parts (electroplated, spray-painted and anodized). Measurements have shown that the coating (plated and spray-painted) has already stripped coating down to bare Alu. Despite of the fact that bared Al is exposed, in-house CASS test (3 cycles of 16 hrs each) has shown unexpected results that have left our production engineer puzzled. Though there's weak correlation between the test results and the corrosion resistance and durability, positive results have suggested some form of oxides laid being deposited on the laser-marked surface. Would appreciate if anyone can offer some comments, explanation or envidence to this findings.

Mark Leng
Product Engineer - Singapore
October 2, 2008

letter 50184 above has an instance where laser etching causes rusting on stainless steel. Now your seeing enhanced protective qualities on anodized aluminum. Sounds reasonable- the heat from the laser is oxidizing the surface, causing rust on stainless, and increased oxide build-up on aluminum. Too bad you can't laser the entire anodized surface....

George Brackett III
- Saco, Maine
October 8, 2008