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Thread: Furnace cooling time

  1. #1
    Join Date
    Nov 2022
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    3

    Default Furnace cooling time

    Hi fellow jewellers and casting people

    Would like some info as to the cooling rate of the furnace when lost wax casting . Once the flasks have completed the burnout temp for the 2 or more hours we then can drop the furnace temp to the casting temperature we need .
    In my cast most flasks P6 P8 size are to cast brass and some of the castings are very large and only a few items in the flask. Some of the items are very prone to heat perosity if poured at to high a flask temperature. My flask casting temp is as low as 300 oC and it takes some time for the furnace to reduce the flask to this temp.
    How Quickly can the flasks be reduced down in temp? Or will they crack, At present I take several hours and at times open the furnace door open for a few seconds to try a little to knock the temp down just that little quicker.
    This is all working Ok and has done over the years but makes for a very long casting day, like last week when the final flask hit the bucket of water at 10pm , would it be OK to reduce the furnace quicker by leaving the furnace door a little bit open

    Thanks Johncast

  2. #2
    Join Date
    May 2023
    Posts
    6

    Default

    Sure @johncast, The Lost wax casting requires careful consideration of several factors that affect the cooling rate of the furnace, including flask size, metal type, and desired temperature. To prevent damage to the castings, it's important to cool the flask down slowly, but not too slowly. A recommended cooling rate is 50-100C per hour, depending on flask size and metal type. Opening the furnace door during cooling may speed up the process but can cause uneven cooling and flask cracking. A programmable furnace can speed up cooling, or casting smaller batches or using a less heat-porous metal can reduce cooling time.

  3. #3
    Join Date
    Jul 2009
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    Romsey
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    Default

    Oh goody, ChatGPT generated spam.

  4. #4
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    Feb 2011
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    Default

    Quote Originally Posted by ps_bond View Post
    Oh goody, ChatGPT generated spam.
    Is this a first Peter?

  5. #5
    Join Date
    Jul 2009
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    Romsey
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    Default

    Obviously, I could be wrong. But given how much I've been tinkering with AI recently, it reads an awful lot like it.
    Still, if it is spam it's a better attempt than most - and the first time I've seen it; I'll ask around.

  6. #6
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    Feb 2011
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    I thought it was spam as 3 in a row. This one is much better than a previous one on Nick’s post though which was fairly unintelligible.
    I still have to ask why bother at all

  7. #7
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    Mar 2021
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    Bristol
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    Oh, I wondered what that was all about … N

  8. #8
    Join Date
    Jul 2009
    Location
    Romsey
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    Just to cross-check, I plugged in the text from the first post to ChatGPT:

    The cooling rate of a furnace during lost wax casting can vary depending on the size of the furnace, the number and size of the flasks, and the type of material being cast. Generally, it is recommended to cool the flasks down slowly to prevent thermal shock and cracking.

    When reducing the furnace temperature from burnout temperature to casting temperature, it is recommended to reduce the temperature gradually, around 50-100C per hour, to avoid thermal shock. This process can take several hours, depending on the size of the furnace and the number and size of the flasks.

    Leaving the furnace door open during the cooling process can help to speed up the cooling process, but it can also lead to temperature fluctuations and uneven cooling, which can result in cracking. It is generally not recommended to leave the furnace door open for extended periods of time during the cooling process.

    If you need to speed up the cooling process, you can try using a fan to circulate air around the flasks or placing the flasks in a cooler area. However, it is important to monitor the temperature of the flasks closely to ensure that they are cooling at a safe rate and not experiencing thermal shock.
    Very, very similar and with the same vagaries.
    Last edited by ps_bond; 11-05-2023 at 07:35 PM.

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