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Thread: Surface Tension of Aluminum

  1. #1
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    Surface Tension of Aluminum

    Hi Everyone,

    I have been trying to cast a typical eating fork, but can't seem to get the aluminum to flow beyond just past the neck of the fork where the prongs are located. I have tried casting from the handle side, the prongs side, and both. I tried putting a block of wood touching the prongs when I create the mold so there is a clear path to the prongs. None of these methods have worked to get the prongs to fill with aluminum. I was thinking it could be caused by either the surface tension of the liquid aluminum being greater than the available space of the prongs or perhaps there was air pressure - hence my trying to pour from both sides of the mold. Anyone have a solution?

  2. #2
    Senior Member HT1's Avatar
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    first, forks are not cast, but if you must rotate the mold so the tines are on the bottom, still questionable because you are up against the minimum casting thickness which is 1/4 for aluminum, so you may have to consider centrifugal casting like jewelers do

    V/r HT1

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    Mrasche, It's important to specify the metal being used and your method or approach. To better understand your issue. If it's pure Aluminum it doesn't have great flow characteristics.
    Quote Originally Posted by HT1 View Post
    so you may have to consider centrifugal casting like jewelers do V/r HT1
    Or even die casting. If your using a alloy with good castability look into the metal content. From scrap or otherwise. It may be free-flowing when sand casting but unwise to use as a utensil it may contain a high percentage of lead. Metals from Asian countries flood our market contaminating it and our bodies.

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    Moderator DavidF's Avatar
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    Going to need some pictures of what you are doing....
    Hmm casting a fork? Might just have to try that one.
    A calm sea does not make a skilled sailor...
    http://thehomefoundry.org

  5. #5
    I know that it can be done with a spoon, not sure about a fork tho but I agree with the others, you would need a good casting alloy to be able to pull it off. I really wouldnt mess with aluminum as eating utensils really, too many acids in food tend to react with the aluminum and dissolves it very easily. It also makes it into more or less a water soluble aluminum compound that is pretty nasty to the body most of the time.

    If I were to try it for a test of skill or something, you would need to overheat the metal a bit since thinner parts need to be hotter to flow, and to just flux the metal quite a bit with a 50/50 salt flux. Ive gotten A356 to flow down to 3/32" through a part through that method. Here's a link of someone doing it for skill and showing thier stuff for a spoon.
    http://www.foundry101.com/racert2.htm

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    At HT1: I think that addresses my question, what I am trying to cast is too small for the aluminum to flow through. Thanks

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    At AricMettle: I am using aluminum and a Petrobond molding of a stainless steel fork. The forks always seem to "disappear" at our house so I thought if I could make some spares, it might solve that issue. You are the first of two people to mention the potential dangers of using aluminum for utensils, so I guess it is not only a pain, but dangerous. Thanks for the advice.

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    At DavidF: if you get it to work, please let me know how you did it. I may not use it as a eating fork, but my pride wants to at least cast it :-)

    - - - Updated - - -

    At CAE2100: I'll take a look and see if it provides any insights. Thanks

  7. #7
    Senior Member HT1's Avatar
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    Quote Originally Posted by cae2100 View Post
    I know that it can be done with a spoon, not sure about a fork tho but I agree with the others, you would need a good casting alloy to be able to pull it off. I really wouldnt mess with aluminum as eating utensils really, too many acids in food tend to react with the aluminum and dissolves it very easily. It also makes it into more or less a water soluble aluminum compound that is pretty nasty to the body most of the time.

    If I were to try it for a test of skill or something, you would need to overheat the metal a bit since thinner parts need to be hotter to flow, and to just flux the metal quite a bit with a 50/50 salt flux. Ive gotten A356 to flow down to 3/32" through a part through that method. Here's a link of someone doing it for skill and showing thier stuff for a spoon.
    http://www.foundry101.com/racert2.htm
    when you do a saucer cup and spoon you always pour it upside down, and choose a meaty spoon, if it fails in the pour(coldshuts) it is almost always right at the end of the handle or at the top of the spoon bowl, those are the thinnest parts the bowl of the spoon is pretty likely to come out because of all the metal in the cup preheating the sand. the end of the spoon is the lowest point in the mold, and it is quite low if you do it right so lots of head pressure , though it has to be vented perfectly through the drag or you will have other issues.

    if you look closely at mine, it has a little loose sand on the spoon handle lowest point in the mold... loose sand goes here

    V/r HT1

    P.S. aluminum plays havoc with dairy products

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    Mrasche, Your welcome I'm a newbie to this myself so what ever questions someone has takes me on the same journey of research. Good luck with your projects. Thank you for adding further details.

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