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Thread: Lost wax casting question

  1. #1
    Join Date
    Oct 2020
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    2

    Default Lost wax casting question

    Hello all.
    First post here, so please be kind.

    I was talking to someone recently about lost wax casting and they asked what temperature is needed to melt brass and silver. I said between 900 and 1000 Celsius.
    They then asked why a torch is used when a kiln can get that hot?
    So question is, with a lost wax, could the metal be placed in the sprue, the whole thing put in a kiln so the metal melts and drips into the cavity?

    Don't know the answer so just asking.

    Thanks.

    S

  2. #2
    Join Date
    Dec 2014
    Location
    South Australia
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    Default

    No lost wax casting requires more than gravity to invest the metal, and the mold would get hot, this is what I understand some more au fait with the process may correct me
    Last edited by china; 12-10-2020 at 03:54 PM.

  3. #3
    Join Date
    Mar 2011
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    Manchester UK
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    As China said above you need to heat the flask in a burnout cycle so maybe 200 deg c then upto 720 deg c then drop to casting temp maybe 550 deg c then while its hot use vacuum or centrifugal force to get the density of the metal in the mould. You can gravity cast but don't get the reliability and fill of forced casting. If you get the investment too hot ie. Hot enough to melt silver it will break down the investment and you will get a poor cast. One of the problems with casting resin is the resin burns out at a higher temp than wax and that.s getting upto the breakdown temp. You can use an Elecromelt to melt the metal instead of a torch

  4. #4
    Join Date
    Oct 2020
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    Default

    Thanks for the replies.
    Sand casting works by gravity though, why not this way?

  5. #5
    Join Date
    Mar 2011
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    Manchester UK
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    sand casting does not really give the detail required for jewellery casting. There is a system called delph casting that is gravity casting but its limited

  6. #6
    Join Date
    Jul 2009
    Location
    Romsey
    Posts
    4,952

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    The other issue with Delft clay is that you use massive pouring sprues, so you're reliant on a large mass of metal to provide the force to fill the mould.
    Steam casting allows for melting the metal in situ, but you'll still need to burnout the mould as a separate operation.

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