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Mixed materials

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  • Mixed materials

    A quick question here.

    I have an aluminium part that I press fittings into post-anodising. I've been having problems pressing these fittings without damaging the finished side of the material. These fittings are stainless steel.

    Does anyone see any problem with putting these fittings on first and then anodising?

    I'm sure the answer will be 'no - don't do it' but surprise me!

  • #2

    Don't do it with exposed parts! Steel, even stainless, will dissolve.

    I have a similar problem, steel parts pressed onto aluminum, which I plan to mask w/ Caswells masking liquid, but I haven't yet tested it to see how well it works. I'm hoping to be able to do so w/in the next week or two.

    Seans Zinc Plating page


    • #3
      so the only way is to press then mask?

      hmmm...big problem here - I don't have any mask!

      I'll just keep trying to press them in afterwards I guess.

      Thanks though.

      EDIT: Okay - I'm trying to find a maskant (peelable) here in the UK. Speed demon isn't open so can't call them. I've seen stuff for PCB's - its latex based I think. Any thoughts on whether that would stand up?


      • #4
        I have had good luck using plain old rubber cement as a mask. It peels easily, and will stand up to the entire ano process.
        With parts that are pressed into a blind hole, I have had good luck using a rubber stopper or even a piece of dowel shaped with a pencil sharpener to use a a plug, then finish the exposed edges with the rubber cement.
        Be careful of the "strings" though!
        I do things.


        • #5
          What do you have the best results applying your mask with?


          • #6
            I have ordered some stuff for pcb's (only because if I ordered it when I did I would have it for tomorrow) that is water insoluable.

            After that I'll try to get a hold of some rubber cement and try that - thanks acid raid.

            I have been experimenting a bit more today and think that there is not alternative but to mask - finish - then anodise the parts Its a shame really as they where coming out perfect.


            • #7
              Okay - anyone looking for rubber cement here in the UK - GIVE UP!

              Apparently its illegal

              I did find some stuff though that I'm just testing now thats acrylic based so - you never know - I might have the answer soon enough - will keep you posted

              EDIT: I should have said 'keep your eyes PEELED' but that would have been tooo cheesy!


              • #8
                A bit of an update here - the stuff I found was acrylic based which worked okay in the sodium hydroxide and great in the rest of the process. Anyone in the UK looking for a peelable mask should use this stuff.

                Now the question stands - when do you put on the mask. I would preferr to put it on after the deoxidiser but I'm not sure - any thoughts? How long do you think you could leave a part after the deoxiding bath before it became problematic?

                I'm thinking of doing a good clean, deoxi, dry, mask, quick deoxi, and then anodise. Any thoughts?

                I need a mask drying time of about 30mins under heat.


                • #9
                  We run racks of parts through the cleaning, etching, and desmut once in a while, and then let then they sit for a while before being anodized. It doesn't cause us any problems that I am aware of. We do a quick final cleanning solution dip and rinse though, just before putting them in the anodizing tank.


                  • #10

                    Now the question stands - when do you put on the mask.
                    I've managed to get a test piece done. Check my web page:

                    The liquid mask works well, but it's a very thick consistency, & difficult to apply with accuracy onto small areas. I plan to thin it for another test.

                    Turns out that powder coat holds up fine through an anodize process, so my problem is solved. I will PC my steel areas first, then anodize.
                    Seans Zinc Plating page


                    • #11
                      Good info Seanc, thanks!


                      • #12
                        I have several parts that I used to press fit SS bearing into anodized aluminum parts. Now I just red loctite the bearing into the aluminum part instead of pressing. It is much easier to install the bearings now!!!

                        One catch: Loctite doesn't like SS or Anodized Aluminum so you have to mask of the area that the loctited part is mating with.