Induction Heater Plans

[lazersteve]

The max temperature remains to be seen.

Steve

 

[Platdigger]

I don't believe there is really a limit to the temperature that can be obtained with this process.
That is, until you reach a point were you don't have sufficient power to overcome the heat losses, the stuff you are melting vaporizes, or you reach the limit of your container.
I mean, you can melt just about any metal with one of these.
Randy

 

[Harold_V]

I don't believe there is really a limit to the temperature that can be obtained with this process. Randy

Typically, you're limited by the refractory and handling equipment.

Harold

 

[peter i]

We have a couple of induktion furnaces at the department of chemistry (used for growing crystals). They will melt a tungsten rod when asked to :wink:

At high temperatures, heat is lost rapidly by radiation, and the moment you lose the same amount of heat as you pour in, the temperature will reach a steady state.

(And a very nice coil!)

 

[Gotrek]

Wow what a great job I can't wai to see it in action.

 

[Froggy]

Where are you at on this steve?

 

[lazersteve]

Frog,

I have secured all the parts for the unit, but I haven't finished the assembly phase. After assembly will be set up and testing.

A friend of mine had the opportunity to test some Platinum in several induction heaters and did not have good results. He tried melting 150+ grams in a variety of manufactured induction heaters from low frequency types to higher frequency types (3kW-15kW). He was only able to achieve slight surface melting.

It's worth noting he did not have access to any refractory materials to prevent the convection of heat away from the test material. It may be that the refractory is a requirement for melting. I'm sure it would help.

Since his tests, I decided to buy a hydrogen torch to complete my Pt DVD. I'm finalizing the edits on my Pt DVD and should have it completed soon.

Yesterday I found some more information on dissolving Pt that should be useful on cats if the information I have found proves to be true. Considering the source of the material, I'm certain of it's accuracy, but skeptical on the proper conditions listed in the manual.

Steve

 

[Froggy]

I was chatting with the gal at http://www.inductiontech.com/page12.shtml and she coulndt express enough how important the power supply was,, for pt etc. it needs to be 10,000 cycles...40kw? Wonder what kind of crucible your friend was using? I have been invited up to North Texas Refinery to try out cat material in a commercial induction heater made by the company above, the guy who owns the place said I had free access to his equipment,lab, and his staff!! He has been thinking of doing something with converters and would be more than willing to help me, obviously he wants me to help him.. I also contacted a company in Cali.---Kinburski bros.-- about melting cats in induction furnaces, no one was there except the sec. and the lab guy, what luck, the lab guy rattled on with all kinds of useful info, they do use induction heaters for recovery of metals in Cats, said it was simple and that the flux has to be really soupy. I will be travelling to N.T Refinery this week and will take pics, wish me luck. Frog

 

[Harold_V]

I was chatting with the gal at http://www.inductiontech.com/page12.shtml and she coulndt express enough how important the power supply was,, for pt etc. it needs to be 10,000 cycles...40kw?

You need to talk to someone else.

As an induction furnace owner, assuming you intend to melt metals, I know that the frequency and power are related to the size of the charge in question, and nothing else. If you are heating metallic substances, it makes no difference if they be platinum or iron. It's the size of the charge that dictates frequency. If you desire to melt a half ounce of platinum, the frequency must by much higher than for melting 50 pounds. Power is a function of speed, although you must have enough power to yield the desired results. Greater power simply shortens the time to melting.

Non metallic substances can be heated equally as well, although higher frequencies are required. Think microwave oven.

Harold

 

[Palladium]

If you are heating metallic substances, it makes no difference if they be platinum or iron. It's the size of the charge that dictates frequency. If you desire to melt a half ounce of platinum, the frequency must by much higher than for melting 50 pounds. Power is a function of speed, although you must have enough power to yield the desired results. Greater power simply shortens the time to melting. Harold

Not only is it the size of the charge, It's also the density of the material involved. Frequencies will penetrate different metals at different depths because of the frequency.

 

[Palladium]

A friend of mine had the opportunity to test some Platinum in several induction heaters and did not have good results. He tried melting 150+ grams in a variety of manufactured induction heaters from low frequency types to higher frequency types (3kW-15kW). He was only able to achieve slight surface melting. Steve

Huummmm. Should have worked. Check this out steve. Note the numbers. :wink: http://www.scienceinafrica.co.za/2003/november/toaster.htm

 

[Froggy]

So Harold your saying the old cliche' "size matters"? I didnt go into details about our conversation but, She said the same things you are saying..... The nice thing thing that came out of our conversation was the redirection she sent me. ie... why bother trying to build one or buy one when you can use someone elses for testing or production (at the capacity I want to do). Like I said earlier, this week I will be with a few lab techs. at this refinery and they can help out, I'm just bringing my limited knoweledge about cats to the table... Actually, looking at my notes it was a guy in Fla. that said 10,000 cycle for pgm's , then he went on a tirade about alot of stuff, after listening to him I thanked him and went about my way(Marvin-Republic metals )....

 

[Harold_V]

Not only is it the size of the charge, It's also the density of the material involved. Frequencies will penetrate different metals at different depths because of the frequency.

That's correct. If you start with chips (waste material from machining processes), an induction furnace may not be able to melt them directly without starting with a larger mass of material. Higher frequency can avoid the problem, but may be too high for heating a given volume once it is molten. As the volume of melted material changes, so to do the characteristics of the furnace. Older furnaces, such as the one I own (motor generator type), have a series of water cooled capacitors that can be constantly switched to compensate for power factor. It changes as solids are liquefied.

The latest generation of induction furnaces (solid state) compensate by other means.

Harold

 

[Harold_V]

why bother trying to build one or buy one when you can use someone elses for testing or production (at the capacity I want to do).

At the risk of offending, I can't imagine anyone without a considerable background in electronics and some serious machine tools at their disposal being able to build an induction furnace of any size that would be useful for anything besides lab work.

The power involved is immense (mine requires a 400 amp service, three phase, and it's a small furnace in the scheme of things), as are the components. One is not likely to build anything that serves a purpose of processing cats in volume. Even then, the same problems must be overcome. Dissolving (or melting) the constituents of catalytic converters will present problems for the lining of an induction furnace. That is not to be taken lightly. If your lining fails, you short the coil----and destroy the furnace power supply. Induction furnaces are expensive, and have the potential to be dangerous. They should be respected.

Harold

edit: added missing word

 

[Froggy]

No offence, I plainly lay my ignorance out for all to see in this field, thats why I am going to a company that has 3 induction furnaces and a full lab with techs.... I wish I had spent months on this proccess rather than the chemical methods, but I still enjoyed all the information i have picked up....

 

[jimwig]

hey there lz.....

you left out one thing on your list ---- make it work.........

this is what i have come up with so far......

http://www.dansworkshop.com/Induction%20Heating.shtml
http://www.richieburnett.co.uk/indheat.html
http://www.ameritherm.com/
http://www.rdoent.com/induction-generator.htm
http://www.ameritherm.com/aboutinduction.php
http://www.popsci.com/diy/article/2003-09/smelting-microwave

some of these are not directly about induction - the last one is more like microwave melting....... that's not melting your microwave.

but there is one that is llike really recent and good. can't put my finger on it but i will.

hope this some kind of help

 

[Anonymous]

Dear Steve,
What you have done is outstanding,
I would also be interested in obtaining a kit, if ever is available.

However I have some questions. If we follow the resonant frequency of 125kHz and use the formula to compute the inductance of a coil

Inductance = D*D*n*n/(18*D+40*l)
where 'D' is the outside diamenter in inches, 'n' is the number of turns and 'l' is the length of the coil in inches, and plug the values for D=4 inches, n = 4 and l=4 inches,

I obtain for inductance 1.1034 uH

using the resonant frequency formula 2*pi*f = 1/sqrt(LC)
and solving for C, the matching capacitor would be 1.46uF

My question is, wouldn't it be better to have larger inductor so the size of the capacitor would be smaller?

for example, lets say 8 turns --> L=4.41uH --> C = 0.367 uF

Great work.
Ram

 

[scwiers]

newbie q:
now that I got my WVO furnace all tuned up, induction is already my next want. And if I had a clue as to how to read schematics and do electrical testing, I'd be raiding some junked microwave ovens in my garage in a flash. Or hold out for Steve's kit.

Seriously though, I'm wondering how induction might help out melting my alloys on a small scale. Right now, pretty much I'm reducing chlorides that I get from liquor. Mostly Cu, with trace PMs. I gather that reducing oxides/chlorides etc. by induction is a no-no, right?

Still, once I get the reduced metal, if I could guarantee that a 1 kg melt, say, was at least 50-75% Cu, for inquartation purposes, I'm wondering if induction could be the key.

And as everyone else has already said, great coil, Steve.

 

[lazersteve]

Ram,

The capacitor provides the necessary power for the coil circuit in the form of charge or Q (coulombs).

The formula for Q is Q=C * E where C is the capacitance and E is the voltage.

The power formula is Q= a * t where a= amps and t = time.

A larger capacitor equals more charge which in turn will produce more power in a shorter time.

Aside from that observation, I didn't design the circuit or the component values, Kim Ladha did.

Steve

 

[kjavanb123]

Hi Steve,

So what happened to this project?

Regards
Kevin