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anodize film thickness

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  • anodize film thickness

    According to Caswell, I should be getting 1 mil thickness on my parts. I am doing everything as suggested in instructions and with talking to tech support. I still only get a few thousandths thickness at best. My parts soak up dye very fast, and if left in dye too long, they will become too dark. my first paying job had to be redone because blue4A was left in for all of 2 minutes, and they were almost black when they came out. Some of that dye also came off in the nickel acetate sealer cycle.

    According to tech support, my anodize film is not thick enough, and it should take some time - like up to 15 minutes for dye to soak in.

    What could be the issue here?

  • #2
    What are your process parameters?
    Time in the ano bath?
    Process Area?
    H2SO4 concentration?
    Ano bath temperature?
    Dye pH?
    Dye temperature?

    It should take 15-20 minutes to dye properly.
    With out knowing more, I'd say your pore's are too big and you are getting a massive amount of dye in the pore causing darker colors, but it simply washes out in the sealer. Just a guess though.

    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 LIKE the post
    I'm not an Amateur Metal Finisher. I've just been around the industry for a dozen years or so helping and consulting when and where I can.


    • #3
      I'm not retyping the whole process, but you can find it here:

      My problem ended up being a bad batch of red dye, but the process is detailed very well.


      • #4
        The only thing I did not see covered in my thread I listed are the actual parts I am working on. The parts I am doing are around 6 sq. in. I do two at once so say 12 sq. in. Using the 720 rule calculator, that puts me at .5 amps for 120 min with a peak voltage of 15. It stays right around these settings throughout the process. This is a current density of 6 amp/ft.

        Ano bath temp is about 65-70F. The concentration is set to whatever Caswell recommends, which I can't recall at the moment.

        The dye PH has been checked for each color, and is correct, and heated to about 120-130F.


        • #5
          please give us a call at 315-946-1213 xt116 and maybe we can help talk you thru this
          Jason Vanderbroek
          315 946 1213 x116


          • #6
            1 mil film thickness is 2 thousands. 1 mill on either side is 2 thousands increase.... So it's sounds like you are getting plenty of thickness.
            It can be difficult to get a full mil thickness using the LCD method. At the 68-72 temp range you start to run into dissolution around the .8 .9 mil area..
            You shouldn't need to dye anything for 15 minutes.. Most of my colors get dyed for 1-3 minutes with a few at 5 minutes....
            With your colors going almost black it sounds like you may be anodizing 7 series aluminum.. You need to make some adjustments for 7 series to get good colors.
            Get a heater to bring your bath up to 68 when you start a run. 65 starts the pores off too small then as temp increases the pores get larger and causes crowding/damage to the structure which can cause dying problems and fall out in sealer.