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Titanium contact to aluminum

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  • Titanium contact to aluminum

    Question 1: Referring to the diagram, will this amount of contact be enough for a good-enough anodize?
    Note: there is no force pushing the Ti against Al

    We're doing thousands of small parts, and require a fast way connect them.

    Question 2: If the Al parts are pressed together firmly, will the current go through all of them, without anodizing between their contact points? (Keeping in mind, the contact between aluminum parts doesn't have to be anodized.)

    Question 3: Does Ti alloy matter when anodizing? Will a Titanium 6al-4v welding rod work?
    Attached Files
    Last edited by TeachME; 05-14-2020, 05:55 PM.

  • #2
    Answer 1: You need to give us more information. Is the AL and TI going into the bath together? How are you racking these?

    Answer 2A: This sounds a lot like barrel/basket anodizing where you put hundreds or thousands of parts in a basket or barrel and anodize the whole lot together. With this type of anodizing, you will always get parts that don't anodize and other that don't anodize well enough to pass quality inspections, but since there are so many in the basket, you can still get enough good parts to fill the order.

    Answer 2B: No anodizing will occur if the electrons (being ejected from the cathodes) can't get to the part. And it's not just getting to the part, but every surface of the part the requires anodizing. Therefore, if you anodize 2 flat parts that are touching on a flat face, the parts will not have any anodic coating on the touching faces. In order to anodize, the part faces must be in contact with the bath solution AND electrons must be able to get to the faces.

    Answer 3: Does TI alloy matter for what?

    To get better answers, you need to post a bit more information. The answer to a vague and general question will usually either be vague and general or it will include guessing. I personal don't like to guess so I end up giving vague and general answers which typically aren't helpful. Please include more details in what you are asking to get the best answers for your situation.
    Last edited by KevinB; 05-15-2020, 11:54 AM.
    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.

    Comment


    • #3
      Originally posted by KevinB View Post
      Answer 1: You need to give us more information. Is the AL and TI going into the bath ---
      Thanks Kevin,

      1. Yes, the Al and Ti are going in the bath together. Referring to the 2nd diagram, the aluminum parts (1 mm thick), will slide onto the Ti rod. The aluminum parts will be pressed together gently.
      However, they won't be pressing against the Ti rod.

      2b. In this case, we want the current passing through between the faces of Al that are touching. Essentially having one block of Aluminum/using the surface we don't need anodized, as a contact for current to pass through from part to part.
      Because of the part geometry and number of parts, our only option is to use the hole as a contact point. We're hoping if we press the Al together, the current will pass through all of the parts (acting as a conductor), and only one contact point will be required from the Ti rod.

      3. Does Ti alloy matter for quality/speed of anodizing. We're looking at Gr 5 rods used for welding, which have 90% Ti.

      Referring again to the first diagram, the question is how much contact between the aluminum parts and Ti, is required to properly anodize.
      Example: does the Al have to be pressing into the Ti?
      How much surface area of Ti must be in contact with Al?
      Attached Files
      Last edited by TeachME; 05-15-2020, 10:56 AM.

      Comment


      • #4
        Using the setup in your second picture you will only be anodizing the outside perimeter off each piece and only the exposed faces of the end pieces. If this is what you want, then we are now on the same page.

        Having the AL simply slid on to the TI will probably not be good enough. If the parts are loose on the TI rod, they will not have a good contact and will mostly likely either start to arc in the bath or simply fall off (although you could fix that by bending the rod upward). You need a good solid connection to your parts to have good repeatable results. Given what I think know about your situation, I would use a piece of threaded TI and put a nut on both sides of the parts and snug the connection up.

        The Gr 5 alloy (aka Ti6Al4V) is fine and commonly used for racking.

        I can't say how much contact is required, but it's not much and it depends on the surface area being processed (small parts need <1-2 mm^2 probably). The less contact area you have, the more resistance you have. The more resistance you have, the more heat you create, and if you don't have enough contact area you will get localized heating and eventual burning.
        Last edited by KevinB; 05-15-2020, 06:17 PM.
        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.

        Comment


        • #5
          Originally posted by KevinB View Post
          Using the setup in your second picture you will only be anodizing the outside perimeter off each piece and only the exposed faces of the end pieces. If this is what you want, then we are now on the same page.

          Having the AL simply slid on to the TI will probably not be good enough. If the parts are loose on the TI rod, they will not have a good contact and will mostly likely either start to arc in the bath or simply fall off( although you could fix that by best the rob upward). You need a good solid connection to your parts to have good repeatable results. Given what I think know about your situation, I would use a piece of threaded TI and put a nut on both sides of the parts and snug the connection up.

          The Gr 5 alloy (aka Ti6Al4V) is fine and commonly used for racking.

          I can't say how much contact is required, but it's not much and it depends on the surface area being processed (small parts need <1-2 mm^2 probably). The less contact area you have, the more resistance you have. The more resistance you have, the more heat you create, and if you don't have enough contact area, you will get localized heating and eventual burning.
          Thanks for the help and advice!

          Comment

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