Letter 18067

Uneven CED coating of Stainless Steel [Thailand] 

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Our coating parts are made of stainless steel with not complex shape. After CED coating some area have uneven film, it can see clearly that film thickness is so different. I have checked and have adjusted spray force of rinsing but no improvement. I would like to know why it occur and how to do. Another question how can I improve film adhesion of this substrate.

Thank you forward to your kind response.

John Stroker
- Thailand

Frankly, it is difficult to answer without being able to examine the problem. None the less, lets try. What do you mean my uneven - is the DFT very different. Have you verified that using a good DFT measuring instrument? Or do you have orange peel? Or does the film have a texture?

It is difficult to have variable film thickness especially to the extent that is is visible to naked eye. CED normally works +/- 2 microns.

Orange peel could be becuase of improper coating power supply. Check the output from the rectifier.

A texture - pig skin effect could come from incorrect P/B value.

Hope this points you in the correct direction!

Gurvin Singh Coatec India - Mohali, Punjab, India

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