Metal finishing Q&As since 1989

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Autophoretic painting

 

What is the difference in the performance parameters of the autophoretic painting on chassis frame - 1. if painting is done on the various parts individually and then assemble them. 2. if painting is done on the assembled chassis directly?

Sachin Gupta
- Jamshedpur, Jharkhand, India

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Dear Sir,

As the supplier of autophoretic coatings in Europe I suspect the issue you wish to address is the possibility of "bleed out" from overlapping joints and welds. Naturally this is a problem for all dip processes.The best solution is to engineer the problem out, by providing good drainage holes and if possible opening up the gaps between overlaps (raising the areas around spot welds typically). If this is not possible then the issue you may suffer could be entrapment of cleaner on the basis of first (solution) in, last out (usually in the oven). (A) low bake schedule (~100C) helps minimize this. The other counter measure is to dip in water first to fill the capillaries with water rather than alkali.

On some occasions dirty reaction rinse solutions can also lead to brown staining. If so change the post ACC rinse and reaction rinse solutions. I hope you find these ideas helpful.

Andy Thomas
- Milton Keynes, Berks, UK