monstermetal

Tell me about your Induction forge

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I think I am about ready to hand Grant a wad of dough for an induction forge and I am a little unsure about the size of machine to buy.... The one Grant is using is a 35 KW.... I know the two primary sizes he sells are 15KW and 25KW...

I do big-ish stuff and think the 25KW is probably the smallest machine id by... I am just to afraid I would regret going with the 15KW.... But now I am worried maybe I should go with a larger machine yet... 30 kw or 35 kw....

I see machines on ebay that are 60KW that are not much more money than the small ones... Im going to buy one through Grant but I assume the same would hold true that the bigger ones are not way more expensive than the small ones once you get to a point ( the ebay ones one twice as big is only about 1/6 more money)

Anyway this is one of those things I really need to get right the first time... And its a lot of scratch, especially now...

So you guys that own machines.... How do you feel? do you think you should have bought a bigger machine or does the unit you bought do everything and more?

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I think I am about ready to hand Grant a wad of dough for an induction forge and I am a little unsure about the size of machine to buy.... The one Grant is using is a 35 KW.... I know the two primary sizes he sells are 15KW and 25KW...

I do big-ish stuff and think the 25KW is probably the smallest machine id by... I am just to afraid I would regret going with the 15KW.... But now I am worried maybe I should go with a larger machine yet... 30 kw or 35 kw....

I see machines on ebay that are 60KW that are not much more money than the small ones... Im going to buy one through Grant but I assume the same would hold true that the bigger ones are not way more expensive than the small ones once you get to a point ( the ebay ones one twice as big is only about 1/6 more money)

Anyway this is one of those things I really need to get right the first time... And its a lot of scratch, especially now...

So you guys that own machines.... How do you feel? do you think you should have bought a bigger machine or does the unit you bought do everything and more?


I think it may be more of a useful exercise to you if you specify the sizes and types of work you are going to be using it on.

A 15kw may be adequate and perform A1 for others, wheras it may be totally inappropriate for your situation,

Personally I would prefer to go for over performance, you can always regulate from higher to lower, but you can't regulate lower to beyond its capabilities.

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That's part of the problem. I don't have an operation in mind or a set of parameters to work within. I am not a production shop. However it's way more common for me to work 2" bar than 1/4". I know no machine will do everything another consideration is the bigger machines require much more plumbing and cooling. Also 380v power

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That's part of the problem. I don't have an operation in mind or a set of parameters to work within. I am not a production shop. However it's way more common for me to work 2" bar than 1/4". I know no machine will do everything another consideration is the bigger machines require much more plumbing and cooling. Also 380v power


I think we are on the way to answering your question, 2" more common than 1/4"

You don't have to be a 'production' shop, these tools are versatile and even your non production shop has multiple runs and unique shapes from your designs from what we have seen of your work,

Do you have 380v power and an adequate water supply or will these have to be factored in, and if so are you prepared for the financial/disruption consequences.

Sort these out and I would think you are well on your way to a considered decision, then try and get a demo arranged if possible.

Good luck with your choice

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Larry,
I'm finding it hard to believe that you would even consider not getting the biggest machine possible...is this the kinder, gentler Monster...? laugh.gif
-DB

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Larry,
In a given month what materials do you run? How about in a typical year?
What are the practical limits of your forging equipment?
What are the most frequent job types you run?
What is the time of return on the investment?
Where do you for see this equipment taking you in that time frame? After that time?

I know you have posted about working some large stock and drops, and your equipment is beyond what many here have seen.

You don't need to tell us the answers, but this is something to think about.

Phil

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Larry:
What does Grant say would work best for you?

Frosty the Lucky.

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Grant says send me a check. We will work out the details later

I talked with him this morning and am leaning torwards the 25kw machine. I think the "big" stuff will still be more practical in a gas forge

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Grant says send me a check. We will work out the details later

I talked with him this morning and am leaning torwards the 25kw machine. I think the "big" stuff will still be more practical in a gas forge


I sure wish I knew more about the things. I recall from a recent question they heat only a short depth, 1/16" IIRC so maybe having less wattage meaning slower heating would equate to deeper heat.

One thing I know for sure is I'd love to have one, as expensive as elec is here it still beats $3.99/gl for propane. A pickup load of coal is an all day expedition to the mine and a lot of digging and packing your own.

Oh well, if I wanted easy I'd take up knitting.

Frosty the Lucky.

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How adjustable for HZ are the machines that you are considering? Generally speaking smaller parts run higher HZ than heavy sections. IIRC the induction furnace we ran at the foundry was only around 400HZ, and we were melting 25Kg at a shot. There are units out there now in the MHz ranges for tiny parts.

Another big factor is the coil,and the coupling effect that you can get to the part being heated. Part of my duties at work is setting up the zone annealer we have. Pretty sure it is the 25KW unit, we had 3 at one time. Our parts run through a horseshoe shaped coil held over a rotating wheel/fixture. It doesn't take much movement up, or down to really affect the heating time, at a set output. The width of the coil opening also makes a big difference on some parts. The closer fit the better. You have to be able to get the part well into the fields generated by the coil. Too far away, and more power is needed to project the fields out farther to reach. That can lead to overheating of the system because the coil can't dump the heat fast enough. We run the coil water through a chiller to maintain temp.

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Didn't david hyde recently get a 25 kw and wishes he got the 35 kw because it would be more forgiving on heating smaller bars in larger coils? Is the larger machine therefore more versatile or just not efficient and wasteful? I would love one but only have 220v and may be limited to 15 kw. Not sure if larger machine are avail in 220v or not.
Rob

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Didn't david hyde recently get a 25 kw and wishes he got the 35 kw because it would be more forgiving on heating smaller bars in larger coils? Is the larger machine therefore more versatile or just not efficient and wasteful? I would love one but only have 220v and may be limited to 15 kw. Not sure if larger machine are avail in 220v or not.
Rob



Yeah, I did kinda kick myself for not getting a 35KVA. I'm still finding my way round uses for the machine but one thing I like is being able to heat on the fly with a flick of a switch. Some times I want to feed large irregular pieces of work through the coils so the largeer coil I have on it, the more "wiggly wiggly curly wurly" bits I can get through the coil. The looser the fit between the coil and the work, the lower the coupling efficiency. To my way of thinking the more Amps you can pass through the coil, the more Amps will be induced into the work and so maybe overcome some of the poor coupling. Just a gut reaction, no science or real observation there. I think the energy used is related to the amps induced in the work, not what are flowing through the coil (it's probably around 90 deg out of phase with the voltage under no load). Poor coupling efficiency refers to the efficiency of converting the electomagnetic field of the coil into a shortcircuit current in the workpiece, not the effeciency of energy use .... I think.

It does get complicated because the machine relies on the inductance of the coil to do all it's self tuning gubbins re frequency, and coil geometry affects this. The amount of amps also seems to depend on what is in the coil. Sometimes on full power and a big chunk of steel in it it starts quite low, say around 300A and this automatically increases up to say a 1000A when the steel goes none magnetic.

The numner of turns on the coils used is also an issue. It would be good to have a longer coil but I haven't had time to play around and find what the limits are. It does seem you can use more turns with non magnetic metals. I'm not sure if a more powerful machine can overcome any limits on using longer coils/ more turns.

These machines are wonderfully simple to use (the frequency is automatically adjusted) but the physics behind them isn't. I guess it would be possible to use some science to work out varius aspects of the performance with differnt coil geometry, metals, power etc but it probably comes down to sucking and seeing.

One thing is that a more powerful machine probably wont speed up the time to heat large section of metal. Above about say 40 or 50mm diameter on mine, the outer surface will spark and burn before the core gets hot. You need to use lower power with very big sections and allow time for the heat to sink in.

Re cooling, yeah a bigger machine needs more cooling. That said on my 25KVA I'm only using a little Tweco TIG cooler. This really isn't good for more than a few minutes before the water gets too hot and the machine shuts down. However I also use my slack tub as a heat excahnger using the pump in the TIG cooler more for circulation. This was suggested by Mike B, more info on this page It does allow for pretty much continuous heating as I use it. That said, the 25KVA is only rated at an 80% duty cycle, the 35KVA has a 100%.

Now if I add a thermostat and microprocessor control to my slack tub I can have it hooked up to the interenet so it can have a chat with my toaster back home and when it dies it will go to silicon heaven. (Any early Red Dwarf fans out there?)

It is actually sods law that now I've got the heater, my next bit of work is a few months of more or less cut and weld so the only use the machine will see is me playing around with coil geometry. It does look like I may have a large bronze railing job in a few months so the machine will be great for that .. hey ho, it sure will be great being able to directly see the colour of the bronze.

Re bigger machines how often do we buy a machine and almost immeadiatley kick ourselfs for not getting a bigger one. I'm genreally of the attitude to stretch myself and get the biggest (for most machines) you can afford and have space for; they usually become idespensible

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Ok here is my confession..

I dont need an induction forge.. there is no way that it would pencil out as a business purchase. That holds true for pretty much all of my forging equipment. I make my money doing industrial fabrication and repair.. I work forged items into my day to day stuff because I have the ability to do so... but to say I need a 200 ton forging press or a 3B Nazel to conduct business would be a flat out lie... In times past a large part of my income was generated by architectural ironwork... I would say 70% or better... so when that was true I forged quite a bit that went into a product... but since the collapse of the housing market I would say less than 10% of my work comes from residential ironwork... The way my shop operates is I work hard at the industrial stuff because I have a large overhead... a 6500 sq foot shop doesn't come cheap and just keeping up dozens of machine tools costs a bit.... The forge shop is there because I like it... its my "hobby" for lack of a better term.... I would like to be able to spend "work" time in the forge but the reality is it could not support itself currently... The reasoning behind the induction forge is simple.... I had a motorcycle... I thought to myself... You know I would rather have an induction forge than that motorcycle that I haven't ridden in two years and needs a bunch of work and money to be what I want.... So I sold the motorcycle.... How does that equate to what size induction forge I should buy? Well.... I dont know. Thats kind of why i posted this... I was really looking for more of a current induction forge users "feeling" about what the machine does.... I know there is limitations for every machine.... And I really dont know what it is I want for an answer... Five grand for a middle sized machine is a pretty big gamble for something that is not a income generating proposition.... I guess I was hoping to hear " the 25KW will do everything the 35KW will do only not as fast"" or "you really need the 35KW if most of your stuff is over an 1"" So something to steer me... Grant has been helpful... which is one of the reasons I plan to buy a machine through him even if its more money... Having a knowledgeable person willing to walk you though something like this is worth way more than saving a few hundred dollars (its about 10% more) But if having a 35KW machine at $6000 is going to make a big difference.... I sure want to know now and not after I have the 25KW up and running in the shop....

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Ok here is my confession..

I dont need an induction forge.. there is no way that it would pencil out as a business purchase. That holds true for pretty much all of my forging equipment. I make my money doing industrial fabrication and repair.. I work forged items into my day to day stuff because I have the ability to do so... but to say I need a 200 ton forging press or a 3B Nazel to conduct business would be a flat out lie... In times past a large part of my income was generated by architectural ironwork... I would say 70% or better... so when that was true I forged quite a bit that went into a product... but since the collapse of the housing market I would say less than 10% of my work comes from residential ironwork... The way my shop operates is I work hard at the industrial stuff because I have a large overhead... a 6500 sq foot shop doesn't come cheap and just keeping up dozens of machine tools costs a bit.... The forge shop is there because I like it... its my "hobby" for lack of a better term.... I would like to be able to spend "work" time in the forge but the reality is it could not support itself currently... The reasoning behind the induction forge is simple.... I had a motorcycle... I thought to myself... You know I would rather have an induction forge than that motorcycle that I haven't ridden in two years and needs a bunch of work and money to be what I want.... So I sold the motorcycle.... How does that equate to what size induction forge I should buy? Well.... I dont know. Thats kind of why i posted this... I was really looking for more of a current induction forge users "feeling" about what the machine does.... I know there is limitations for every machine.... And I really dont know what it is I want for an answer... Five grand for a middle sized machine is a pretty big gamble for something that is not a income generating proposition.... I guess I was hoping to hear " the 25KW will do everything the 35KW will do only not as fast"" or "you really need the 35KW if most of your stuff is over an 1"" So something to steer me... Grant has been helpful... which is one of the reasons I plan to buy a machine through him even if its more money... Having a knowledgeable person willing to walk you though something like this is worth way more than saving a few hundred dollars (its about 10% more) But if having a 35KW machine at $6000 is going to make a big difference.... I sure want to know now and not after I have the 25KW up and running in the shop....


I can relate to that, on a bean counter level there isn't much justification for it but I just HAD to have one. Part the reason behind running my business it that it will pay for toys tools that I just couldn't begin to afford if I did what I do just as a hobby. My work is my hobby is my work .... is my life!

Could you get round to Grants and have a play with his 35KVA machine and compare this to the 25KVA. If Grant hasn't got one in stock you could maybe compare it to some of 15KVA machines as shown on you tube.

I'm very happy with my 25KVA machine. Part of the deal with me getting one was I got a good price and would have got one on the 35, which is why with hindsight I should really have got the 35. If I had to pay the full price, the 35 might have been just a bit out of my budget but I would definitely have gone for the 25 rather than the 15

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I have the smaller machine because of the electrical limitations (single phase only). Would I like a larger machine? Yup. Sure don't mind having the little one though. When its too big I use gas. Thats easy. If your machine is more for your "hobby" maybe the smaller is the way to go. I think the process is way better suited to heat longer sections of smaller diameter stock than big hunks of mass.

Induction definitely changes the way you work. If I start playing with some forms I'll get sucked in and really get into experimenting. "Just one more heat". Then two hours later maybe back to the task at hand. So from a creative perspective you'll be happy with any of them.

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I have the smaller machine because of the electrical limitations (single phase only). Would I like a larger machine? Yup. Sure don't mind having the little one though. When its too big I use gas. Thats easy. If your machine is more for your "hobby" maybe the smaller is the way to go. I think the process is way better suited to heat longer sections of smaller diameter stock than big hunks of mass.

Induction definitely changes the way you work. If I start playing with some forms I'll get sucked in and really get into experimenting. "Just one more heat". Then two hours later maybe back to the task at hand. So from a creative perspective you'll be happy with any of them.


Screw that, get the big one.

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Am I correct that the 15kv is about $3000 the 25kv is about $5000 and the 35kv is about $6000 and the 25 and 35 both need 440 volt 3 phase. Is the only one that can run on 220v single or 3 phase is the 15kv model? It would be nice to have a larger unit but being limited to 220v there may not be choice of machine. :(
Rob

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Am I correct that the 15kv is about $3000 the 25kv is about $5000 and the 35kv is about $6000 and the 25 and 35 both need 440 volt 3 phase. Is the only one that can run on 220v single or 3 phase is the 15kv model? It would be nice to have a larger unit but being limited to 220v there may not be choice of machine. :(
Rob



I'm not sure of the prices your side of the pond but if these are typical and you've got the electric supply and the choice is the 35 or 25 I'd definitely say get the 35 for the extra $1000. Especially so given the the 35 has a 100% duty cycle and the 25 an 80%. It's that old saying you can do anything on large lathe/anvi//forge/etc/etc that you can on a small one but not the other way round.

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Thank you, I don't think it is easy for me to get 440 volts here. I only have 220v service. I have not done enough homework to know if the only machine that works on 220v is the 15kv model. I hope there is a bigger one available that works on 220v.
Rob

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The 25 can be had in 220 three phase.

Another consideration is cooling. The 35 requires a lot more water which means a bigger pump and cooling capacity. All of the 35 and up machines I've installed included refrigeration type chillers, another $3000.00 or so.

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Thank you Grant. Can you post a balpark price so I have an idea of how much to save and will it function off a rotary phase converter or does it need "pure" power due to the electronics?
Monster, Are you going for the 220v one to be able to relocate in the future?
Rob

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