Lost Foam Dip Coating Rig – The Big Dipper

Discussion in 'Lost foam casting' started by Al2O3, Jun 9, 2019.

  1. Tony

    Tony Copper

    We do not use the lost foam method as we are mass production and it would be much to slow of a process for our scale (in my plant alone we melt about 80 ton of iron per hour). I personally find it fascinating though and can see so many possibilities with investment casting that are not feasible with green sand casting.
    Keep up the good work.

    Tony
     
  2. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Like most casting processes, it has its place. Before I started down the lost foam path, I watched a lot of videos. When I saw what was be accomplished in commercial settings with the process, I thought all of the processes (with the possible exception of molding expanded polystyrene foam patterns) could be made practical for a home/hobby foundry and small quantity and one-off production. After I started experimenting with machining extruded polystyrene, that was the last element. So I figured why not learn and lift what I could from commercial practice? It seems a great deal more investment has been made in the method elsewhere in the world. There were a handful of videos and companies that were the most useful sources of process information but this one had more info and adoptable process details than any other and you might find it interesting to see the process on a commercial scale. They of course make process equipment for the industry. There may be US based companies too but I couldn't find them.

    The YouTube video is 38minute summary of their process flow.


    http://www.ruioulfc.com/high-technology/

    ....and EU LF council

    https://lostfoamcouncil.de/the-advantages.html

    Best,
    Kelly
     
    Anders Lundholm likes this.
  3. Melterskelter

    Melterskelter Gold Banner Member

    Interesting that at 1:17 I see a variant of Brunhilda’s Bra! There is nothing new under the Sun!

    Denis
     
  4. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Yes indeed Denis. I think in addition to an aiming device it's also a metering device of sorts, or at least a buffer that insures a minimum feed rate. Essentially just a pouring cup with orifice but interesting that there is a gap. It picks up again at about the 29 minute mark. They talk about the "beat" of the pour being slow-fast-slow.....which is what I refer to as the lost foam pause. I think that is caused by initially, the metal contact rapidly evaporates foam. Then once the metal starts advancing through the pattern it is separated from the foam by liquid and gaseous phase foam which insulates the pattern from the metal front until the gas heats up and an it starts advancing more rapidly......it's hard to get use to.

    Best,
    Kelly
     
  5. Sorry, I jump in here i have googel "slurry" typ Poly cap and run ower this so i feel it´s importment to use "slurry" but hard to fins company in Sweden
     

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  6. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Poly Cap 600 is a trade name owned by the parent company REFCOTEC. They have a location near me so I use it.

    If you are casting aluminum and non-ferrous alloys, non-setting drywall joint compound works well if you thin it with water. Not sure what it's called in Finland but it is the material used to fill/finish the joints (on top the tape) on gypsum board home construction materials. It can be thinned to a brushable or thinner to dipping consistency. Here is a thread where I discuss dipping.

    http://forums.thehomefoundry.org/index.php?threads/dip-coating-polystyrene-foam.573/

    It is very inexpensive and can be purchased here in the US at all the home improvement stores. If you only cast occasionally and have patterns with accessible surfaces, applying with a brush is very practical. If you have patterns with difficult to reach features or casting more frequently, dipping is fast.

    In all cases they are air dried. Warm air up to 40c dries the coating much faster. I placed the patterns under a box sitting on top a heating vent in my house during the winter.

    Best,
    Kelly
     
  7. Al2O3

    Al2O3 Administrator Staff Member Banner Member

    Here's a Video discussing lost foam refractory coating materials and application methods.



    Best,
    Kelly
     

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