Metal finishing Q&As since 1989

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Too much TDS in our stage 1 cleaning

September 22, 2009

Hi my name is Linda, I am a quality manager in a wood window manufacturing co. We operate a 3 stage emersion pretreatment system in our Powder Coating line. ( Clean and phosphate, DI Rinse and Seal Rinse). I have been having a problem with excess TDS in the Stage 1 tank. we are only running about 2500 to 3000 parts through the tanks per week. I am having to change out the tank about every six to eight weeks. The metal we are using is 6063 T5 aluminum. Since we are a small manufacturing Co this is becoming costly. I would appreciate any advice you can give me

Thanks,
Linda Martin

Linda Martin
Quality Assurance - Ste. Genevieve, Missouri

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My first question would be, where is the sludge(TDS?) coming from? Maybe your phos concentration is to high and the excess is settling on the bottom of the tank(It should be about 2%). Don't forget that the tank is pulling double duty, but the chemicals should last 6 months at the rate you are using them. I used to scrape bottom of my tank with a shovel on the weekend when the pumps were off and the water was cold.

Sheldon Taylor
supply chain electronics
Wake Forest, North Carolina
September 24, 2009