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Fluidized bed coating

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  • Fluidized bed coating

    Anybody have any exp, with fluidized beds. I am thinking of getting a small one. I have a small foundry and am casting aluminum. I need to develop a small production coating line. I only need one color. Do you guys feel I can produce CONSISTANT results if I do my part? Meaning proper part prep and preheat to avoid outgassing. I need to gang them up say 10 or so at a time preheat and dip then finish cure. I realize my coating thickness will be considerably thicker than e-stat but my products will need to be durable in a marine environment. Time saved using this method will thwart to added powder volume cost. any ideas or tips and cautions are greatly appreciated.

  • #2
    It all really depends on configuration of your part I suppose. I've done this process many times with great success. Make no mistake about it though..... if you pre-heat your part to powder cure temperature and there's a scrap the part or get busy with the sandblaster. There's some more advanced beds out on the market that have an actual electrostatic "push" to them but I don't think you mean those. If your casting mass is kept low and has no variable thick spots, I'd say you won't have too much of a problem with it. Of course, there will be an obvious learning curve in the beginning before you get a "feel" for what works. This is to be expected though. I also wouldn't worry about using excess powder to the point of it being overly costly either. Keep your dip-times quick and finish your cures as recommended by powder manufacturer and you'll do just fine. (for those curious...this process rivals electrostatic spray by using the excess powder on the part as opposed to the loss you have in the booth or filter of your vacuum as far as powder useage goes).

    So all in all...a viable way to coat something, albeit a specific purpose type of application. I don't think you'll have many problems though. But then again.... I don't see why you would have excessive outgassing from small cast parts either unless the quality of the case gives you obvious large holes. Maybe on of the coaters here can do a "test piece" for this gentleman (at a small cost, of course. They have to pay for the powder and oven time) to show him how it would look electrostatically applied versus going out and buying a fluid bed system? Could be a cost effective way to find out if you want to buy a gun or not..... any takers willing to help this gentleman out,hummmmm?......Russ


    • #3
      If you need a test piece coated electrostatically, let me know. I'd be more than willing to help out. Just drop me a pm or email at [email protected].


      • #4

        Thanks Non-Stick for the great info! I knew you would come through....
        The part is a basic rectangle 1" x 3/4" in section x 8" long with soft edges,the handle portion does not need coating as it will have a vina foam grip. I think the mass of the part will lend itself to this sort of process" It will stay hot enough long enough. I like the idea of e-stat but I just dont want to spent hours and hours in the booth. Time is where the money is. I agree on the learning curve"Good thing I have a furnace" Will I have a problem with moisture? I can see getting 40#'s of powder too damp to fluidixe real easy. Any ideas? Do you feel I could fabricate a fixture and e-stat say 10 at a time? I guess I'm asking "How much pull will the part have on the atomized powder" will it be able to sneak around corners a little? Sorry to hammer you with all the questions but I am a loss on this part of my product development!
        Thanks to Tom for the offer! If I was not in Alaska I would take you up on it! The Offer does not go un-appreciated!
        When I get some more made I may still take you up on it. I am revising my production tooling as we speak!


        • #5
          I don't really see where the huge time savings are going to take place on your substrate, truth be known. Electrostatic Application (e-stat) has it's time and place as well as fluidized bed coatings. I just happen to think you are going to be over engineering the wheel, if I may be so bold. As far as designing a rack.... the parts themselves can become thier own rack. Just for giggles.... let's set up an example with make believe "widgets", shall we?

          Widgets are 1 3/4" X 8" long box tubing (look familiar?)

          Now..... take and make a "hook" so that it looks like this "[". Make about 50 of them. Good.... now insert the top portion of the 90-degree angle into the open end of the widget. Do the same with the other side now. You now have a widget with two of these "[..........]" on either side.... With me so far? Good. Now....take another widget and hang on the free ends of those hooks. See how you just magically linked those together? One widget right on top of the other and now connected by a metal hook. Repeat this process linking widget to widget until you have maybe 8 or so of them together. Looks like a bunch of widgets chained together by hooks, right? You just made the widget the rack, my friend. Simple as that. Now you've just increased production time by 700%, therefore blowing the theory out of the water that fluidized beds would be faster in this example. ( I keep telling you people it's all in the prep! pay attention next time I speak,lol). To finish your "widget rack"...just take two more of those hooks and bend the top portion into something that resembles a coathanger type of curve (enough so that it will hang on a steel bar) for the top part. Now repeat the ENTIRE process as many times as need be to fill your oven chamber. This process will get you "volumetric efficiency". They will coat like a DREAM and depending on oven size.... you may be able to fit a few hundred widgets into the oven to be fired all at once. Coat them all, bake them all at once and you are now done. While your operator is waiting for the parts to bake and cure, he can be setting up for the next round or coating something else while the oven comes up to temperature. ( See how cost effective this is becoming now,hummmmm?). The whole process of an oven load of widgets in that manner should take you no longer than an hour or so. (the more you do things, the faster you will become at them). Again.... these widget numbers are just an example, as I do not know what oven size you have. Adjust accordingly.
          The fact of all that is...... you just made "e-stat" tons faster and operator friendly ( e-stat is a set it and forget it type of thing.... fluid beds need your FULL attention while in process). I still say that your very own "widget" application is best suited for a powder gun and I stand by that fact. Again.... send a test piece out via U.S. Postal or UPS to anybody willing to help you out ( be fair and pay these guys a bit for what they do, please. Also guys.... be fair and help him out for he's in the same boat you are, basically!) to see what you should expect. It's a real world example, I say.

          As far as coverages are concerned, yes. The powder will have a wrap around effect. This is where powder coatings excel. Electrostaic coatings (liquid AND powder) attract to any surface with a ground. It builds up in one area...then keeps wanting to find the path of least resistance. Therefore.... keeps moving to fresh metal.

          Also... Yes, moisture and humidity WILL be a problem in fluidized bed applications. You are exposing the surface area of the polymer to ambient air multiplied by thousands..... no, millions of times what you would normally be doing in an e-stat application. As anybody can attaest.... moisture is the biggest killer to any powder. It gets throw it away. Period. Reclaim is not an option at that point without sufficiently drying it out (which I have yet to see happen without $$$$ machinery involved).

          As for the questions and hammering me.... everybody can tell you from here, I love getting up on the soapbox for all to listen,lol. Keep em coming Good luck and take the advice for what it's worth with somebody who's coated "widgets" like yours before in that manner..... it works and is THE way to go. Hope that helps you...... Russ


          • #6

            Thanks non-stick You have me figured out I have allways been very good at re-inventing the wheel. As it turned out yesterday after I posted, one of my customers came in and has a e-stat set-up. One of those from "another company", He saw my widget and I gave it to him to coat out. He has some of that "allmost Chrome" We will see what happens. I actually had ideas of wrinkle red. but I want to see how durable the coating is. If it works out I may sub the work to him. If I give them to him a few hundred at a time it should be cost effective.Keep you posted!
            Thanks again Will


            • #7
              8 knots,
              i hope you asked your friend that has equipment from "other company", to buy powder he needs from caswell seeing you got so much help from his forum


              • #8
                Don't fret..... As we discussed my project I showed him all the good stuff Caswell has to offer! He was impressed with the site and did show interest in buying from them!


                • #9
                  bewdy mate, good on ya,
                  caswell needs all the orders we can put his way, to keep ahead of the competition, & make this the best site in the "hobby" finishing world.