Induction Heating 101: A Practical Guide for Blacksmiths

I explain the fundamentals of induction heating, give a tour of my induction heater and cooling system, and go over some examples principles of good coil design.
Please let me know if you liked this video. I'd like to increase my production quality like this going forward, but I need to know if it's worth the extra effort!
Music: Local Forecast - Elevator by Kevin MacLeod incompetech.com/
EJ of the Anvil 120V/240V conversion: • LH-15A 110v to 220v co...
EJ's C coil:
• Good coil for blacksmi...
Derek Melton's Induction Forge: www.derekmelton.com/my-induct...
mettleworks.com/

[@auglazeallday5335]

I've watched 15 vids before finding this one and none of them actually informed me how these worked. Thank you for describing the inner workings of the forge. 👍

[@MauledByBears]

Glad you found it useful! Thank you

[@_Junkers]

I hope you carry this format of technical brief followed by show and tell into your future videos. Very entertaining/engaging.

[@MauledByBears]

Thank you! I appreciate that. I worked hard to put this one together, hoping to do more of these in the future

[@ILoveProjects]

Thanks for sharing the valuable advices I have not seen anywhere else. What I learned: - opt for the 240-volt version instead of the 120-volt version for better power and performance - furnace cement as electric isolator: protect coils by dipping them in furnace cement, which helps prevent short-circuiting and premature wear - 50/50 mix of propylene glycol and distilled water as a coolant - radiator type idea is valueable - use 1/4 tubing for coils, instead of 8mm (rare in US) - spacing coil loops as tight as possible (about half the tube diameter) to minimize leakage of magnetic field lines and improve heating efficiency and some other, that I did not clearly understand. :)

[@MauledByBears]

You got the gist! Thanks for watching

[@laelcosta7060]

As a hobby blacksmith with a math/physics background, I am very appreciative of the combination of technical and practical aspects!

[@MauledByBears]

Glad I could do the topic justice!

[@paulkline1574]

About 10 seconds in, I wanted to start taking notes and raising my hand to ask questions. Amazing job!

[@MauledByBears]

Ha! Thanks. Glad you liked it

[@firstmkb]

That was absolutely the perfect mix of some theory with practical use! Excellent presentation!

[@MauledByBears]

Thanks for watching!

[@bartonius1063]

This is the ideal nerdiness level! Great video thanks!

[@MauledByBears]

Ha! Glad I didn't get TOO nerdy for you

[@dayannahkali]

Super instructive video, thanks a lot. I was on the verge to buy a propane forge, but as soon as I've seen what induction heaters are capable of, I knew it was for me. Super quick and energy efficient, safe, no fumes, plus, it gives the finest grain size for knifemaking!

[@tinbjj]

Hey man, I'm planning to buy one for kmifemaking, how is it going? Are you satisfied with the induction forging? Thank you very much 😊🙌

[@dayannahkali]

@@tinbjj In the end, I have started with a propane one after failing to diy with an induction heater... I keep my money to buy a furnace one day, cause I'm more interested in high carbide steels that need a stable high temperature and not much by forging etc. For now I am just messing around with 1075...

[@wheretimehasnovalue9343]

Wow. Great Technical Detail and Explanation. Man you need to build and supply these out to us in the South

[@y-notforge8913]

..Very informative video sir. You took a lot of the mystery out of this magical machine for me...!

[@MauledByBears]

Thanks! Glad I could help demystify it a little. I dunno about you, but the machine is still magical to me even though I know how it works!

[@sparkybluefox]

Thank you for posting this video ! I've been out of the Induction heating field for 25 years, but I used to do a lot of lab work with induction heating coil projects. Such a great intro to IGBT devices ! They were just coming in when I was leaving the field ! I will not go into the firms that I used to work for.... but it was for for a couple decades. SBF

[@tobiashangler]

Amazing video! Thanks so much for the time and effort that surely went into the making.

[@MauledByBears]

Thank you!

[@wesleyfrancis7590]

That was a great video. You nailed your objective, just the right amount of info. Supper informative well explained but you didn’t waste time on unnecessary details. Thank you.

[@MauledByBears]

Thank you! It was my goal to trim the fat and give you the good stuff

[@stankrieger3598]

My first info search on this heat system. You did a great job on explaining just how it works to me the newbie

[@MauledByBears]

Thanks!

[@paradiselost9946]

used to run some big industrial ones. i miss watching 2 inch bar vaporise :) had to get all this certification from the power company to get them installed... you can make the lines as long as you want, you have to simply make them as capacitors. ok, to a degree... there is a limit. it starts affecting the tank circuit and the coupling transformers, gets out of its range... depending how the machine works... we happily ran two meters, and at some point got coax line as well... not cheap? two waterlines and some real funky impedance... think of the circuit as voltage stored in a capacitor, and current in the magnetic field. you only want the current, the magnetic field, at the workpiece. everywhere else you want it as voltage in the capacitor. used 4~6 inch wide sheets of copper/brass plate soldered to the pipes, brass/nylon fasteners clamping them to thin hdpe sheet. the thinner the better... dont exceed the dielectric strength. 1mm is fine for nearly everything... that is, if you tend to not like being right in front of the machine? i dont. if changing coils a lot, the choice of compression fitting and how theyre mounted/supported counts. you dont want the pipes getting all twisted up, and needing three spanners at once sux. the weirdest one i had was making a little pancake coil. i had thrown just about everything at this machine, and then this one threw me a "phase error"... wtf? lingering memories of the internals... open up, poke around... ah ha! one little jumper, "phase". then every other coil threw me "phase error" until i flipped it back... wish i had had a scope... i spent ages hunting down ceramic rods... spent a fortune... and then realised cheap glass serves the purpose for poking carbide and other bits around when brazing. we were using steel rods with the inevitable occasional zap or short circuit and fault trip... foreman bought in some carbon fiber once. i just laughed, threw it on a coil. BANG! smoke, ash... learnt the hard way with RC planes, lol...

[@MauledByBears]

Thank you! Great comment. Using capacitors is a good idea, though I'm sure they get expensive due to the amount of power flowing through them. Lots of things to think about here. As for your comments on changing coils a lot, I'm working on a solution that uses quick-connects, but finding quick-connects that have ample metal-to-metal contact and also seal is difficult.

[@paradiselost9946]

@@MauledByBears you dont buy capacitors, you simply make all the conductor that ISNT work coil into a capacitor by increasing surface area and inserting a better dielectric than air. copper sheet is pretty cheap by the roll (even cheaper when theres a scrap yard behind your shop, and the neighbours make copper guttering!) and plastic. meh. anywhere.... hdpe/pp is best electrically and mechanically, ptfe is too soft but is possibly the best dielectric, PVC is absolutely USELESS, and nylon becomes conductive around 600v or so.. check dielectric constants first. we gave up on buying fittings, and just made some with o-rings, much like you see on oxy/gas regulators. still plenty of metal contact but sealed with just finger tight.

[@brysonalden5414]

Thanks for taking the time to do this! I still have questions, but I'm about 6 months out from getting one for my smithy, so no doubt more will be revealed.

[@Keith12001]

Very good video, thank you for sharing

[@pleaseyourselfsir]

Now these are my kind of videos I love induction heaters ! 🧐🇬🇧🤔🤝❤️👍🤓

[@neilyakuza6595]

Great explanation, Subscribed!

[@kevin20809]

Excellent explanation thank you. Keep more content coming.

[@MauledByBears]

Thank you! Glad you enjoyed it.

[@rodbambauer3041]

Learned a lot...thanks!

[@MauledByBears]

Thanks Rod

[@johnstubbe3113]

Well done

[@MauledByBears]

Thank you!

[@gert_kruger]

For a given length of wire, the geometry that maximizes inductance is a coil diameter to length ratio closer to one. I don't know where you get the 1:4 ratio. I guess it has to do with the purpose of the coil. For the optimization of energy storage a ratio of one is better. For heating purposes you want to get the flux closer to the heated target, thus a smaller diameter and hence a larger ratio.

[@MauledByBears]

I think I said this in the video, but I got most of the information from Frank Curtis's book on induction heating. Keep in mind that these heater units automatically change the drive frequency to output maximum power and the current delivered can also be changed in real time, so this is far from an idealized engineering scenario! In my practical experience, coils with a 1:1 length to diameter ratio work great, but longer coils are often more practical for larger heats, even if they don't maximize inductance. The 1:4 ratio is a maximum - anything beyond that has diminishing returns in terms of heating rate which in the end is the thing most blacksmiths care about.

[@morganwilliams960]

Awesome video. Do you have any opinions on how large of diameter the heating coil could be (would want a minimum of 3 coil wraps), specific to your machine? I am looking to heat a 6in diameter hollow capped pipe as a pyrolytic chamber for biomass carbonization. Do you think a 6.5 in diameter coil would exceed unit limits? Thanks so much!!

[@MauledByBears]

Great question. Yeah probably too big unless you had single loop coil like I described and you had some way to move the pipe back and forth to heat it evenly. Doing it by hand seems like it would obviate the automatic heater. Alternatively, fill the pipe and throw it in a campfire. Way easier

[@charlesgeary4987]

This was very informative. Good job. One question what is the name of the furnace {?} material used to keep the coil from shorting out with the workpiece?

[@MauledByBears]

I use a piece of fiberglass sheath which doesn't work that well at all. it breaks down quickly from the radiant heat of the workpiece. I recommend either a ceramic product sold by mettleworks or using refractory cement which is cheaper and easier to (re)apply. Thanks for the kind words!

[@blc6464]

Good vid Thanks

[@MauledByBears]

Thanks for watching!

[@MultiElf007]

Very nice video, thank you! I have an idea in my mind, but it is probably crap.. I am thinking about forge welding billets for damascus in inert atmosphere. The setup would me in something like sanding box, where would be induction coil and small hydraulic press. The idea is to vacuum the air out and then fill the box with inert gas. This should prevent oxidation at higher temperatures and assist in clean welds. Probably an overkill :D But the steel shoud be probably polished again in inert atmosphere in order to get rid off of surface oxides before stacking in billets..

[@MauledByBears]

Not a bad idea! Definitely overkill with the vacuum, an argon purge box is probably easier. You'd need a tight fit up, a canister, or flux of some sort to keep the surfaces clean after you pull it out of the purge to weld, but it's possible! A purge box for my heater is on my list of things to build.

[@MultiElf007]

@@MauledByBears I don't think flux would be needed. It's purpose is not to let oxygen to hot metal. If there is no oxygen, no oxide lawyer would be formed. It may be possible to weld some hard to weld steel, like spring steel with higher silica content.

[@MultiElf007]

Oh, I misunderstood. My idea was some box, where you can heat AND forge weld steel. The whole process would be done in that chamber. But this purging would work too. My idea was to prevent fast forming oxide lawyers as well. (When the surface is grinded in oxygen free atmosphere)

[@MauledByBears]

@@MultiElf007 ah yeah well if you can figure it out, more power to you. Flux is cheap insurance so that's what I'll use. You'd need an open coil to fit hydraulic press dies in there so you'd lose power there.

[@dallasb6561]

Great video! Do you use the 15kW model? If so do you think it would be capable of melting a small amount of steel in a crucible?

[@MauledByBears]

Like I say in the video, I think the 15kW term is for marketing purposes. But yes this is that style of heater. Cody's Lab has refined some iron prills with it, it's technically possible but I suspect it's not practical for melting steel.

[@dallasb6561]

@@MauledByBears thank you

[@konanbarbarian4888]

THANKS FOR THE BEAUTIFULL EXPLANATION ,I HAVE A QUESTION SIR, WHAT IS THE ELECTRECITY CONSUMPTION ?IS IT HIGH OR LOW? THANK YOU SIR

[@MauledByBears]

As I explained in the video, it's about a 7.5kW machine. It's capable of running at 100% duty cycle, so potentially 7.5kWh continuous.

[@mckutzy]

This is really cool.. We have them at my workplace, but are big industrial machines... none the less, a home machinelike that would be awesome... This 240vac version you have...How many amps draw does it have???

[@MauledByBears]

Like I said in the video, it's rated for 30A or 7.5kW although I have it on a 30A breaker and I've never popped it.

[@mckutzy]

@@MauledByBears Sorry mate... I didn't catch that part... Thanks for telling me anyways. Appreciate it...

[@MauledByBears]

@@mckutzy No worries, I dropped a lot of info in this video. Something will always slip through :D

[@teun7923]

Superb video, thanks. But I got a question: What breaker amperage do I need for a 240V model? If peak power usage is 15KW then wouldn't I need a 80A breaker ?!

[@MauledByBears]

As I said in the video, it's really a 7.5kW heater. A 30A breaker is more than adequate. I have mine on a 50A breaker

[@teun7923]

@@MauledByBearsAh thanks for the answer. That makes buying one a lot cheaper.

[@michael5529]

Hi, great video, thanks! In the beginning you did say peak power 15kw. Is that realistic? Have you tripped your 50 amp breaker when using it at full power?

[@frenchcreekvalley]

What is actually displayed on the meter in the front? I have seen that the numbers seem to run between a hundred or so and about 800. Is that amperes? Is that watts times 10? Or is it just some number relative to "wide open"? I just bought some of Gene Olson's (Mettleworks) CERAMIC insulation. He says it's about twice as good as fiberglass, by the way.

[@MauledByBears]

I believe it's the amperes in the coil. Higher number means more power is being pushed into the work. I don't mess with the fiber shield. Ceramic may be better than fiberglass but furnace cement is the cheapest and it's far more durable from what I'm told. Thanks for watching!

[@ferrocutter]

Just got a machine that I think is is same as yours HT-15A? Slightly worryingly there doesn’t seem to be any indication of which way around live and neutral of the electrical supply should be connected, could you help me out? Great video by the way I’ve watched it at least 5 times.

[@MauledByBears]

I'm assuming you're in the US and using 240V power. Our 240V in the US isn't like 120V where there's a line and neutral, it's two 120v lines that are 180 degrees out of phase electrically. The net result is 240V AC but it's achieved with two hots. Long story short, doesn't matter. Hook up the hots to the terminals and the ground wire to the chassis and start having fun!

[@ferrocutter]

@@MauledByBears thanks so much for your quick reply, I’m in the UK where domestic supply is 240v with line and neutral, I’ve taken the lid off it and one connection is going straight into a hefty relay then onto some sort of device whereas the other is going straight to the same device. Feeling confident now to connect line to the relay side. Couldn’t get any intelligible information from the vendor or manufacturer. Thanks again.

[@MauledByBears]

@@ferrocutter Good luck! I think you'll be alright

[@johnwest4788]

Thank you so much for that detailed explanation. (I'm hoping to buy one of these). I have a question about a coil design. What if you made a pancake coil that has two pancake shapes side by side so that you can get a large piece of metal in and out without the limits of the standard coils. Would that be more efficient than the bent C or taco coil. If my description is not good enough for you to visualize this, please email me and I'll send a drawing of what I mean. Thanks!

[@MauledByBears]

Hi John, Thanks for the kind words. Yes that would be more efficient than a flat coil because you'd be forcing the flux lines to be more linear and closely packed in the space between coils. But remember that the gap must be small to be efficient so you're still limiting how much space you have. Also, remember that flux is coming out of all surfaces of the coil, so a two big pancake coils will waste a lot of flux out of the back with some relationship to the surface area of the coils combined. Lastly, remember the guideline on the length of tubing used for the coil. The longer the coil, the higher it's resistance (or impedance since we're taking AC). So you need to make sure the coil isn't excessively long since it will waste the finite energy the machine can deliver and you'll end up making a coolant heater rather than a metal heater. Hope that makes sense. Happy to answer and more questions.

[@johnwest4788]

@@MauledByBears Thank you, I didn't realize that you had responded, I guess I didn't set up notifications. Another question. How do you ensure you get all of the sand out of your coils after bending?

[@MauledByBears]

@@johnwest4788 Tap, blow, water rinse. My cooling system has a big tank where any solids can settle easily

[@jmikronis7376]

Try looking at EFD Induction heating.

[@victoryfirst2878]

Would using a larger diameter tubing increase the efficiency of the energy used ??? How about using a thicker wall tubing help to keep heating of the coil at a lower temperature ??? Thanks

[@MauledByBears]

I honestly don't know on either account. I get really fast heating and my coolant doesn't overheat with the tubing I use now and this tubing is easy for me to get. I'd love to use bigger tubing, but 5/16" tube is a little rare in the US and 8mm is unheard of. Anything bigger than that would be annoying to bend into coils. 1/4" tubing works absolutely fine as long as your cooling system is good and most importantly, 1/4" tubing is cheap and easy to find in the US which is where I am.

[@victoryfirst2878]

@@MauledByBears Try McMaster-Carr industrial supply. You will be amazed and pleasantly surprised at the quality and price with most of the stuff made in the USA. Thanks for all the great information also.

[@MauledByBears]

@@victoryfirst2878 Ha! I wish I had the budget to just buy stuff straight from McMaster Carr. Maybe one day

[@coltonstevens1]

Palladium melts at 2800°F. Do you think this machine will get about an ounce of palladium to this temperature? I am building a vacuum casting chamber. Thanks!

[@MauledByBears]

I doubt it would be efficient. Palladium isn't ferromagnetic, so you'd only be heating in the eddy current mode. Any crucible you would use would necessarily worsen the coupling between the sample and the coil. Palladium doesn't corrode easily, I doubt you need a vacuum. An oxy acetylene torch should suffice for melting such a small amount of metal

[@Faysal-fe3dk]

Thsnks a lot.......is 2 kw or less powerful induction heater enough for blacksmith and machine shop??

[@MauledByBears]

You're welcome. This machine is 7.2kW and it can heat up to 1-1/2" (30mm) stock easily. 2kW would be ok, but anything over 1/2" (13mm) would probably take too long to heat to be useful in my opinion. I don't have any firsthand experience with 2kW machines. If you're looking to do blacksmithing, I recommend a bigger unit like this. If you're heat treating cutters for a machine shop or doing small forging and brazing jobs, the 2kW may be sufficient.

[@Faysal-fe3dk]

@@MauledByBears induction heater in my country is too expansive and hard to find... So buying is not possible....... So i have to make it..... And in home 2kw is the maximum limit...... Main purpose of mine is to use it for hardening (gear, pinions, knife.. Etc)..maybe surface hardening to be exact......but i saw in youtube someone malted metal with battery powered induction heater!!!!

[@MauledByBears]

@@Faysal-fe3dk Yeah in that case, I recommend that you don't use induction. A charcoal or coal forge would be easy to build and use. Propane or natural gas is also an option. I don't recommend you make one, they're pretty complex machines and they need to be tuned properly for the work to be done. Additionally when you get into high energy electronics, the danger factor goes up. Even if you did succeed in making one, I think you'd be disappointed in what 2kW can do. My recommendation is charcoal. It's cheap, easy to make, and making a forge to burn it is very simple. Good luck

[@Faysal-fe3dk]

@@MauledByBears thanks

[@mevk1]

@@MauledByBears Very good turtorial, thank you for the explanation on a mystical topic. On the furnace side of things, the 2kw heaters can melt a pound of copper in several minutes. How many pounds of copper alloy do you think this 12kW will melt?

[@jeffputnam8554]

great information. I ordered one of these from Ebay but after being charged for it never received it.

[@MauledByBears]

Oh that sucks! File a claim with eBay or your credit card company. Good luck!

[@mevk1]

What is your power source-internal -amps/volts?

[@MauledByBears]

This heater runs on 240V, 30A. It's wired into a circuit that will handle up to 50A

[@mevk1]

@@MauledByBears Just looked at the McGraw 1944 book and saw a schemtic that looks like the same or very similar ZVS design China is shipping here. If you are looking for content ideas, I'd love to hear you contrast the two designs. Thanks much for digging that up - had no idea this design was so old. Also, wondering how your unit differs from the smaller units that use 48 volt DC server type power supplies - what power supply is inside the 7.5kW heaters? www.rfcafe.com/references/popular-electronics/heat-without-flame-popular-electronics-june-1955.htm

[@andrewnoblett9510]

Hi has anyone tried Fernex gas central heating additive would that work it’s cheap

[@mehranalam1274]

Nice video , Why induction coil get heat up and get red and it does not fully melt the ingote. I have checked the water circulation, temp is above 950 C, time 50 sec. The condition is perfect but still the coil heat up.

[@MauledByBears]

If your coil is getting red, something is wrong. My guess is that you have a coolant blockage and that coolant is not going through the coil.

[@pathan0n]

I got one of these machines a while ago and made coils very similar to yours… but have never got the heating results I was expecting from them. Any ideas as to why? Heats thick bars fine but not flat/thin material like you show.

[@MauledByBears]

Thick materials are usually easier to heat because for a given magnetic flux density, a thick piece of material will be able to able to contain more flux lines than a thinner piece. Thin material will readily show if you have any inefficiency in your coil design. My suggestion is to go back to basics and watch the coil design part of my video again and make sure your coils are designed well. You need good coupling between coil and material and the coil needs to organize those flux lines to be as closely packed as possible. Good luck!

[@pathan0n]

I will do that!! Also going to check out the book you mention. Thanks for the help

[@MauledByBears]

@@pathan0n It should be pretty easy to find for free online, that's where I found it. If you can't, let me know and I'll get you a copy

[@Gubber81]

Are these safe for people with artificial heart valves

[@MauledByBears]

Ooh great question. I don't know! The frequency of the magnetic field is pretty high so it doesn't "feel" like it's there a lot of the time. By that I mean that you don't get the pull or push you normally think of with a magnet, not that strongly at least. Magnetic fields weaken with the square of distance from the pole, so I'd imagine that it's safe unless you put your chest right up to the coil. HOWEVER, I'm not a doctor or an electrical engineer so I simply don't know. I'd err on the side of caution and stay away until you know for sure whether or not they're safe.

[@Gubber81]

@@MauledByBears Thank you for the reply. I have been interested in forging for awhile. I also have a issue with heat. This method seems the best for dealing with the heat issue. I would get too hot with a normal forge.

[@MauledByBears]

@@Gubber81 I can confirm that this forge is fantastic in the summer. Way less heat dumped into the forge and your body. Good luck finding an answer as to whether they're safe for people with heart modifications. Please let me know if you find an answer!

[@Gubber81]

@@MauledByBears I will.

[@dreamstar1616]

I'm Tamilnadu please give me idea for this machine buy

[@MauledByBears]

I work with someone who was born in Chennai! Sorry, I don't know how to help. I suggest contacting the Chinese companies that produce these heaters. Try searching for Lihua induction heaters. Good luck!

[@maxxwiersum4685]

I'm not on any of these steps yet, mine came without hosed or a wire so I'm tryna see what I have to order, short answer no help at all in this video if u want to know of the names of the stuff that's connected to the machine

[@sailingalearningcurve]

I have a couple of questions for you, how does a person look you up for a private conversation?

[@MauledByBears]

You can hit up my Instagram @_scald

[@Gubber81]

The reason I ask is that I am supposed to stay from powerful magnets

[@user-br3ou2cs9o]

Are you still working? No videos for such a long time. 😞

[@MauledByBears]

Ha! Yes, sorry. Been working on a huge job for more than 9 months now. I have some ideas, I'll be back

[@user-br3ou2cs9o]

@@MauledByBears Gotta do whatcha gotta do 💪💪

[@darkokubatka5350]

Samo pričaš pokaži i praktično

[@MauledByBears]

Hvala vam!

[@carltrieb2235]

Absolutely best info I’ve found yet to help me get my knife shop underway. I love induction cooking and have an amazing induction range and two induction portable cooktops and a whole collection of cast iron cookware. I do not have a heat treating system in the shop yet and I’m convinced that induction heat treating with a plate quench is the way to go. I have an unusual ulu hybrid knife design and if you’re interested check out ulukblades on Instagram. My next batch of knives will be made from nitro v and I’m just wondering if there’s any reason that induction could not get the stainless hot enough for quenching? Thanks for making your video.

[@MauledByBears]

Yep stainless will heat just fine in an induction heater. Thanks for the kind words. You could use the induction stove top to temper, probably not to harden though. For tempering, I would put a cast iron pan on the induction stove top, fill it with sand or fine metal shavings and slowly increase the heat until your hardened part is at the right tempering temperature. Clickspring has a good example of a tempering tray filled with brass shavings that he uses to blue small steel parts.

[@carltrieb2235]

@@MauledByBears very interesting idea Going to get some iron powder and try that Thankyou