ABYMC

T3sl4

I'm getting ready to offer induction heater kits and built units.

What good is induction heating? Non-contact heat, clean electrical power, high efficiency, unlimited temperature. The plasma in a fusion reactor -- millions of degrees hot -- is powered by induction. Applications include soldering, brazing, welding, heat treating, forging, melting and more.

Why would you want one? Almost the same reason you want a welder: it's easier. Instead of dicking around with a blinding hot forge or messy coals, you can stick your work into an induction coil, heat it up in a matter of seconds and keep on pounding. Instead of wasting real dollars burning fuel to reach iron and steel-melting temperatures, you can melt anything on demand, paying mere pennies in electrical costs. Specifically, you would want to use this thing for forging steel, melting iron and steel, and any specialty (or production) processes you might have, such as brazing, etc. If all you are doing is melting aluminum and bronze, this machine is not for you -- fire is better for aluminum and bronze.

What's it cost? It looks like a 10kW unit will run around $500 in parts alone. I am considering kits for around $1000, and assembled and tested units for $2000 (these prices are by no means final and I reserve the right to increase or decrease them!). Although fairly expensive for the average ABYMCer, consider that this size heater is comparable to a 300A inverter type welder. 10kW will heat up your work faster than a gas-fired forge, and is capable of melting about 10 pounds of steel in half an hour.

A smaller model, 1-2kW capacity and running from the 120V outlet, might be $100 in parts: a much easier entry into the technology, but also about as limited as a 120V welder box. Still, it's enough for small-scale work, including melting copper, silver and gold (perfect for jewelery!), and some forging work. (I haven't melted steel yet, but I presume you can melt a few ounces of the stuff.)

That's what's in it for you. What I need is: a few people to buy these kits and get me started. This is still on the prototype level, so I actually need two things, funding and feedback. I know a few people who have shown interest before; this time, I'm ready to get serious on the offer. Once the kinks are worked out, I can offer kits and units publically.

Tim
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Danny Uerling · Posted: Thu Jun 04, 2009 6:52 pm Post subject:

Hi Tim,

I might conceivably be interested in the smaller model. Just what would the capacity for this smaller model be? I'm also concerned to know if they are power factor corrected.

Thanks
Danny Uerling
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Burt Prelutsky

T3sl4 · Posted: Fri Jun 05, 2009 3:28 am Post subject:

2kW should be enough to melt a pound of copper, silver or gold, or a half pound of steel. (The rule of thumb is about 1kW per pound of steel, but there's a lot more heat loss on this small scale.) It should be great for light forging work, possibly up to 3/4" dia. bar (if you don't mind waiting).

I have not implemented power factor correction. Keep in mind there are two kinds of power factor, true PF and Displacement Power Factor. By the nature of the power supply circuit, it will have excellent DPF, with phase angle near zero. PF will be low, however, because current is only drawn on the peaks. This is typical of most inverter type electronics, including switching supplies, VFDs, etc.

Tim
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Danny Uerling · Posted: Fri Jun 12, 2009 8:42 pm Post subject:

Tim,

Okay, so the real question is: What will the power company say? Will they likely be concerned about the low "True PF". Also, how much trouble would it be for you to design a correction circuit? If it's not too complicated I suppose I could build it myself.

Thanks,
Danny Uerling
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So far as I’m concerned, contempt of Congress shouldn’t be a crime, it should be an obligation.

Burt Prelutsky

T3sl4 · Posted: Sat Jun 13, 2009 2:42 am Post subject:

Call them and ask if they care. I'd be surprised if you get a reply. It's a mere 15kVA or so, and not in any quantity. Plus, residential power is not metered for reactive power, only real power. I'm guessing I won't be selling many to commercial users.

PFC ranges from removing the filter capacitors (which puts ripple directly on the output, which will give a pleasing BUZZ to the work coil, and may annoy the control circuit) to using a proper PFC boost supply. I'd rather not do the latter, since it's practically another induction heater.

Tim
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Castlestone · Posted: Fri Jun 26, 2009 11:35 am Post subject:

Hi Tim, first time post here for me.
I've been reading everything I can get my hands on about induction furnaces for the past 3 years and while I did come across your stuff last year, this is the first time I came across this site.
I'm interested in electronics and metalcasting so I would be interested in a kit in the smaller size range. You have posted some great practical stuff on the controller and tank circuit so I was planning to model something after what you have done.
The more DIY the better for me and of particular interest would be the purchase of a PCB for the controller.
Wherever this goes, I'll be following with interest.

Mike