Author Topic: induction heater  (Read 1648 times)

Offline shipto

  • Hero Member
  • *****
  • Posts: 758
  • Country: gb
  • Redditch, UK
induction heater
« on: November 12, 2021, 11:13:10 AM »
I brought an induction heater which I have been using to oil blacken some diehead parts but as I didn't have any cooling I have been doing 4-5 then switching it off to allow it to cool. So now I am working on housing it properly (not on a brick  :lol:) and adding cooling.

As luck would have it my daughter replaced her "broken" CPU cooler which when I stripped it apart I found had somehow leaked all the fluid out and was just pumping air around the system, seems daft that they dont give you some way to fill it?

So to start with I swapped the coil on the induction heater from the top to the bottom of the board and cut some aluminium angle to mount to the radiator to get me started. The filler bottle will be fixed at an angle because I plan to be able to use it in two orientations.
Turns out this life c**p is just one big distraction from death but a good one. For the love of god dont give yourself time to think.
https://myshedblog.wordpress.com/

Offline shipto

  • Hero Member
  • *****
  • Posts: 758
  • Country: gb
  • Redditch, UK
Re: induction heater
« Reply #1 on: November 12, 2021, 12:33:02 PM »
After a little thinking about I currently have the setup in the picture but I am now thinking I may modify it a little and make the power supply sit at a slight angle but I am out of aluminium for now so will have to look at it tomorrow.

I am still trying to decide if I should include some kind of timer and auto shut off, I guess I will have to see how it runs once piped up.
Turns out this life c**p is just one big distraction from death but a good one. For the love of god dont give yourself time to think.
https://myshedblog.wordpress.com/

Offline ddmckee54

  • Sr. Member
  • ****
  • Posts: 250
  • Country: us
Re: induction heater
« Reply #2 on: November 12, 2021, 04:16:31 PM »
It'll help, but depending on the size of your heater you're probably going to need more cooling than that radiator can supply.  The induction heaters I've worked on needed a LOT of cooling but they were a little bigger than yours.  If you want to use the induction heater for any length of time, you'll probably need more cooling capacity.  A CPU cooler is probably good for a couple of hundred watts - if that much.

I would imagine that this set-up would be similar to the coolers used on some of the CO2 lasers.  I think those guys start with a bucket of ice-water and shut down when the water gets warm.  On a closed cooling system think BIG and cold, the more thermal mass you have, and the colder it is, the longer you can run.
Too many irons, not enough fire.

Offline shipto

  • Hero Member
  • *****
  • Posts: 758
  • Country: gb
  • Redditch, UK
Re: induction heater
« Reply #3 on: November 12, 2021, 05:03:12 PM »
It'll help, but depending on the size of your heater you're probably going to need more cooling than that radiator can supply.  The induction heaters I've worked on needed a LOT of cooling but they were a little bigger than yours.  If you want to use the induction heater for any length of time, you'll probably need more cooling capacity.  A CPU cooler is probably good for a couple of hundred watts - if that much.

I would imagine that this set-up would be similar to the coolers used on some of the CO2 lasers.  I think those guys start with a bucket of ice-water and shut down when the water gets warm.  On a closed cooling system think BIG and cold, the more thermal mass you have, and the colder it is, the longer you can run.
Thats food for thought but the radiator does have two large fans mounted on it and the pump itself I was going to just mount on the side somewhere but I have a rather large heatsink I could mount it on instead. Might also be worth mounting a temp readout too, not sure how high the ones I have go up to will have to check that tomorrow.
Turns out this life c**p is just one big distraction from death but a good one. For the love of god dont give yourself time to think.
https://myshedblog.wordpress.com/

Offline awemawson

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 8653
  • Country: gb
  • East Sussex, UK
Re: induction heater
« Reply #4 on: November 12, 2021, 05:27:05 PM »
The rule of thumb Iíve worked to is 40% of the output power of the induction furnace is needed for cooling the electronics and the coils and cables.

So my 100 KW output induction furnace originally had a 39 KW refrigeration chiller (which Iíve replaced by a huge heat exchanger fed by 47 litre a minute ground water sourced water supply at about 10.5 degrees C  from my borehole)
Andrew Mawson
East Sussex

Offline shipto

  • Hero Member
  • *****
  • Posts: 758
  • Country: gb
  • Redditch, UK
Re: induction heater
« Reply #5 on: November 12, 2021, 05:57:56 PM »
The rule of thumb Iíve worked to is 40% of the output power of the induction furnace is needed for cooling the electronics and the coils and cables.

So my 100 KW output induction furnace originally had a 39 KW refrigeration chiller (which Iíve replaced by a huge heat exchanger fed by 47 litre a minute ground water sourced water supply at about 10.5 degrees C  from my borehole)
:jaw: Wow your talking a mahooosive way away from what I have, can't remember exactly what it was but this is advertised at 1000-1500 watts or somewhere in that region.
Turns out this life c**p is just one big distraction from death but a good one. For the love of god dont give yourself time to think.
https://myshedblog.wordpress.com/

Offline WeldingRod

  • Sr. Member
  • ****
  • Posts: 393
Re: induction heater
« Reply #6 on: November 13, 2021, 09:49:57 AM »
The other challenge is pushing the coolant through the coil!
Back when I was doing electromagnetic levitation/containerless processing at Rice, I was trying to keep cold from melting down with a kilo Amp of 40 kHz RF going through them.  I had a serious pump and found that 3/16" was the smallest I could use without making steam.  Skinny tubing = induction awesomeness...  I did some stuff with rectangular tubing also, but it really didn't play well with the funny shapes I needed.

So, for your stuff, some suggestions: 

Hook it up to compressed air and a muffler.  Put the throttling valve on the outlet: heat transfer is related to density, and compressed air is more dense.

Hook it up to city water with a long coiled hose to keep the RF out of the pipes.

Make a pressurized water reservoir and pump it up before a heat cycle.

Find a higher presdure pump.  A tiny/cheap/Harbor Fright pressure washer pump isn't insane for this.

Consider larger diameter tubing squashed oval after winding.  Ideally squashed while filled with something like low melting metal.  Also consider installing thin insulation on the coil to allow the turns to be closer together.

Fyi, theres going to be an optimum inductance, if you start changing the coil.  Lower inductance = more current = more heating = higher capacitor current.  The caps are probably your limiting factor!

Sent from my SM-G892A using Tapatalk


Offline awemawson

  • Global Moderator
  • Hero Member
  • *****
  • Posts: 8653
  • Country: gb
  • East Sussex, UK
Re: induction heater
« Reply #7 on: November 13, 2021, 10:26:18 AM »
I'd avoided a total loss system like that running directly through the pipes as they would fur up. Hence my humongous heat exchanger, which also allows glycol as anti-freeze in the furnace water.

I pump the water round using a Grundfoss pump

https://www.madmodder.net/index.php/topic,13100.275.html
Andrew Mawson
East Sussex

Offline shipto

  • Hero Member
  • *****
  • Posts: 758
  • Country: gb
  • Redditch, UK
Re: induction heater
« Reply #8 on: November 14, 2021, 02:52:15 PM »
Had a quick browse through your thread Awemason it looks brilliant. I thank you both for your input but most of it is far outside this project I am just going to have to do what I can and deal with the limitations. I checked on my temperature controller and it will do to set a maximum temp and shut it off if it exceeds it even though it wont deal with the amps alone so its going to need to switch bigger relay. The thermocouple can go into the heatsink the pump is mounted on.
Anyway I did manage to free myself to do a bit today and am now debating with myself about getting a bigger power supply for it which is part of the reason I went for the smaller of the heatsink options I had thought of.

Turns out this life c**p is just one big distraction from death but a good one. For the love of god dont give yourself time to think.
https://myshedblog.wordpress.com/

Offline WeldingRod

  • Sr. Member
  • ****
  • Posts: 393
Re: induction heater
« Reply #9 on: November 14, 2021, 06:05:16 PM »
Make sure you put something in there where you can verify you are getting coolant through it, and not steam!

Sent from my SM-G892A using Tapatalk


Offline PekkaNF

  • Hero Member
  • *****
  • Posts: 2519
  • Country: fi
Re: induction heater
« Reply #10 on: November 15, 2021, 03:48:53 AM »
That cooler might be just a tad to small, also the flow of coolant might be too low. I would check up if that will provide good enough cycle time, if just a tad too marginal....like 50% would be better, then I would add large enough reservoir of coolant to increase thermal mass and larger pump to pump between reservoir and coil and use up that exisisting system of your PC radiator and small pump to cool the reservoir between heavier use and pauses.

Offline shipto

  • Hero Member
  • *****
  • Posts: 758
  • Country: gb
  • Redditch, UK
Re: induction heater
« Reply #11 on: November 27, 2021, 04:35:04 PM »
So despite the cold and my shed heater packing up I still managed a bit of progress. All the bits are fitted and wired up which wasn't hard.
The output from the temperature controller is wired via the main switch so if it gets too high it will switch off automatically and not start again until its cooled to the lower setting, all pretty standard.
I am still undecided about using the plastic bottle as the header tank because fitting it will be awkward and I might make/Aquire something that fits better.
Turns out this life c**p is just one big distraction from death but a good one. For the love of god dont give yourself time to think.
https://myshedblog.wordpress.com/

Offline shipto

  • Hero Member
  • *****
  • Posts: 758
  • Country: gb
  • Redditch, UK
Re: induction heater
« Reply #12 on: November 27, 2021, 04:42:47 PM »
That cooler might be just a tad to small, also the flow of coolant might be too low. I would check up if that will provide good enough cycle time, if just a tad too marginal....like 50% would be better, then I would add large enough reservoir of coolant to increase thermal mass and larger pump to pump between reservoir and coil and use up that exisisting system of your PC radiator and small pump to cool the reservoir between heavier use and pauses.
The way I'm thinking at the moment is I might need a stronger pump but as I managed to use it with no cooling at all some cooling must improve things right? If it turns out not to be enough there is room in there for a bigger pump.
Turns out this life c**p is just one big distraction from death but a good one. For the love of god dont give yourself time to think.
https://myshedblog.wordpress.com/

Offline shipto

  • Hero Member
  • *****
  • Posts: 758
  • Country: gb
  • Redditch, UK
Re: induction heater
« Reply #13 on: November 28, 2021, 09:47:55 AM »
So because I couldn't wait I hooked it up to test it and I am quite happy I ran it for a good while and the temperature never exceeded 17.2C although its not running at anywhere near full power.
I think that in the future I will get a power supply that will run it better, currently its on a 24volt 15amp and even though I haven't checked the amps its drawing it doesn't seem to be putting the power supply under any strain so I think (size permitting) I will get hold of a 36 or 48 volt supply.
There is very little heat in the caps and only a tad more on the mosfets but its providing enough heat to the part to do what I want it for which is mostly going to be oil blackening parts but if I could get enough heat for hardening parts that would be a bonus.
One thing I will do is rotate the pump so the inlet and outlet are at the top to prevent any air lock in the pump, I should have thought of that before actually.
Turns out this life c**p is just one big distraction from death but a good one. For the love of god dont give yourself time to think.
https://myshedblog.wordpress.com/

Offline PekkaNF

  • Hero Member
  • *****
  • Posts: 2519
  • Country: fi
Re: induction heater
« Reply #14 on: November 28, 2021, 11:17:06 AM »
Nice to hear it works on first try.

Thermal management is pretty straightforward in principle, but in practice if can be challenging.

Offline Muzzerboy

  • Full Member
  • ***
  • Posts: 101
  • Country: gb
    • The Mighty Shiz
Re: induction heater
« Reply #15 on: November 29, 2021, 01:48:57 PM »
I'd expect a converter like that, driving the coil directly, would be around 90% efficient and most of the switching losses are in the air cooled FETs. Even if you lost 50% of the resulting HF power in the copper coil, that would still be a fairly modest loss. And given that the power supply is rated at less than 400W, you are not going to challenge the radiator and fan no matter what you do.

Does it say what supply voltage you need to get it up to the claimed 1000W?

Modern processors only take around 30-40W whereas the graphics cards are in the 200-400W region, so I'd hope a water cooling system would be good for 500W or so. That would fit with the tpical PSU rating required these days, given that the output power all ends up as heat.

Offline shipto

  • Hero Member
  • *****
  • Posts: 758
  • Country: gb
  • Redditch, UK
Re: induction heater
« Reply #16 on: November 30, 2021, 05:58:32 PM »
I'd expect a converter like that, driving the coil directly, would be around 90% efficient and most of the switching losses are in the air cooled FETs. Even if you lost 50% of the resulting HF power in the copper coil, that would still be a fairly modest loss. And given that the power supply is rated at less than 400W, you are not going to challenge the radiator and fan no matter what you do.

Does it say what supply voltage you need to get it up to the claimed 1000W?

Modern processors only take around 30-40W whereas the graphics cards are in the 200-400W region, so I'd hope a water cooling system would be good for 500W or so. That would fit with the tpical PSU rating required these days, given that the output power all ends up as heat.
I think 48volts is the maximum they suggest for running this unit but I did hook my meter to it and the unit was drawing 13 amps which goes down to around 7.5 when the part (a M12 bolt) gets as hot as it will go.
Turns out this life c**p is just one big distraction from death but a good one. For the love of god dont give yourself time to think.
https://myshedblog.wordpress.com/