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parts getting eat up. please help!

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  • parts getting eat up. please help!

    Ok guys I'm having some issues. It don't happen every time but every once awhile my parts come out eat up. Sometimes it will be just small pits and other times half or most of the part will be gone. Any help would be appreciated.

    Would not enough agitation be the problem or could my acid ratio to distill water be wrong.

    What is best way to check my acid tank for mixture?

  • #2
    For starters, what format are you running LCD or 12 ASF?
    What is the starting and finishing tank temp?
    Do you have any agitation at all at the moment?
    What Alloy?

    Best way to test your tank is through titration using 1N NaOH (Sodium Hydroxide) and a pH meter.

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    • #3
      All pertinent questions by gardinhackle. The short answer is that your parts are burning. All of the things gh mentions can and do come into play when parts burn. They all need to be addressed. Another thing that should be considered is the part geometry. Small thin parts will burn easier than thick heavy parts, so if your parts are thin, you need to compensate.

      You mentioned small pits. Pitting can also be caused by high chloride content. What kind of water did you use to mix your acid bath? Tap water usually has chlorides to some extent or another.
      Process control doesn't give you good quality, it gives you consistent quality.
      Good quality comes from consistently doing the right things.

      Process control systems for anodizers
      If a post helps you out spread the love and LIKE the post
      _____________________________________________
      Last edited by kevinB: Now. Reason: superfluous typo's

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      • #4
        I'm using the LCD method and I use the flaming paper bag formula to get my settings. I use the pre setting for 6asf. I have plenty of agitation and use air. Can to much or not enough acid be a problem?

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        • #5
          Burning is a result of too much power on the parts. One calculation for power is (Voltage^2/resistance). As the resistance drops (or conductivity increases), the power increases. Therefore a bath that is too conductive will tend to burn parts. When you make up the bath and begin to add acid, the bath's conductivity will begin to rise. Once you reach 30%v/v of acid in the bath, the conductivity peaks. The addition of more acid will then begin to reduce the conductivity. I have seen baths run at peak conductivity without burning, so acid concentration is not likely your (only) problem.

          Do you have any copper around the tank that can have acid splash on it the run back into the tank? Like copper bus bars maybe? Only a little copper in a tank will significantly increase the conductivity and can cause major burning issues.
          Process control doesn't give you good quality, it gives you consistent quality.
          Good quality comes from consistently doing the right things.

          Process control systems for anodizers
          If a post helps you out spread the love and LIKE the post
          _____________________________________________
          Last edited by kevinB: Now. Reason: superfluous typo's

          Comment

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