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Thread: Is an induction furnace really that difficult and expensive ?

  1. #1

    Is an induction furnace really that difficult and expensive ?

    I have seen induction furnaces on several Youtube videos and what strikes is its very quick and low-energy cost operation. High temperatures (even platinum) can be acquired easily.

    E.g I see on the channel luckygen01 a self made induction furnace melting steel.

    But I also see a very complicated setup with oscilloscope, lots of electronics.

    On ebay I find rather affordable 1kW units for low voltage. A DC power supply can be a DC welder which yields 100A.

    Are such units useful for melting small amounts (200ml = 1.4kg) of cast iron ?

  2. #2
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    I suppose a low tech (electronics free) induction melter could be built with some kind of motor-generator set to generate the high frequency. Would be less efficient and louder than a electronics driven machine.

    https://en.wikipedia.org/wiki/Frequency_changer

  3. #3
    Not at all actually, you can make it very basic.
    2 1KW zvs drivers from ebay and you place the above eachother, make a crucible that fits the coils.
    Then use a welding piwer supply or make 2 individual 45V 20A DC power supplies with a microwave over tranformer with diodes.

    Totalling 50 bucks I think, I am really considering this.
    Heating controll can be done easily with a 2 dollar ebay voltage regulator.

  4. #4
    Senior Member Robert's Avatar
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    Those drivers are very interesting. I would love to see someone do this!
    RObert
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    Senior Member Wolfcreek-Steve's Avatar
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    Having worked for a company that built machines around the induction heating principle, (Foil sealing, bolt heat treating, glue curing, etc) There is a lot to getting it set up so it is efficient. I'd be more interested in a carbon arc furnace that could work off of a stick welder as a power supply.
    What is that squeaking noise?

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    Tim who used to post here did a home build induction furnace and even started offering kits, don't know if it was successful (I fell out with him over some comments so didn't keep track of what he was doing) May be worth a search.

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    Senior Member cjcaster's Avatar
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    At one time I had a link to a site that sold induction machines used to melt metal.
    The cost of the smaller units was relatively cheap (relatively being a relative word), perhaps in the $6,500.00 range if I remember correctly.

    The smaller units would operate on 240 volt, 1-phase, but the amount of iron that they would melt was relatively small, perhaps 10 lbs.

    The larger units that would melt about 100 lbs of iron were in the $12,000.00 range, which would have been ok (steep but ok), but........they required 480 volt, 3-phase, which is not good if you only have residential service.

    There was a guy on here I think who had a 3-phase induction melter, and he ran it off a 3-phase generator.
    I don't have the link.

    A generator would probably be cheaper since the utility company will hit you with a demand fee; so if you use the melter once per year, you will pay a monthly demand fee for the peak demand that you set.

    The copper coil of an induction melter is water cooled, and the good units have a chiller and a closed loop system so you don't have to waste water.

    You don't need as much kW with an induction melter since the efficiency is in the 50-70% range, compared to an oil-fired furnace efficiency of 7-15%.

    Here is a small one, perhaps for jewely production.
    https://www.aliexpress.com/item/ZVS-...Fci2wAodccQCFA

    I think the ones I was looking at were like these:
    http://www.ebay.com/itm/like/1123167...&ul_noapp=true

    I reached the conclusion that an oil burner is a poor man's induction melter.

  8. #8
    Senior Member Robert's Avatar
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    "A generator would probably be cheaper since the utility company will hit you with a demand fee; so if you use the melter once per year, you will pay a monthly demand fee for the peak demand that you set.
    "
    Where do you live that you are saying this? The OP was talking about a couple of 1kW units. Not a 60 kW unit! My AC units draw about 12kW at startup. I guess the power consumption would depend on how much iron you wanted to melt.

    Robert
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  9. #9
    There's a bit of a difference between a 120/240V 200 amp single phase residential service and a 480V 400A three phase service and a big difference in how utilities bill them. A resi service has a (relatively) simple meter that measures your kW usage during a billing cycle. Three phase services typically measure peak demand in 15 minute intervals and the utility bills you based on that. What I believe Caster is saying is, based on demand metering, using a large induction furnace could get to be a fairly expensive proposition.

    The other side of this to consider is if you were buy a three phase furnace, you'd still have to convince the electric utility company to run a three phase service to your house so you could run it. Then you'd have to wire a panel for three phase, etc. This all gets expensive in a hurry. Ergo, if you aren't seriously going into the business of running an iron foundry, you're probably a lot better off burning oil than you are an electric means if you want to melt a larger amount of iron.
    "Success is 99% determination"

  10. #10
    Senior Member Robert's Avatar
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    Thanks Jason!
    R
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