Hey there, if you’re scrolling because you’re shopping around for induction furnaces, you’ve probably wondered this at some point: what’s the actual capacity of these things, anyway? I get it—when you’re looking to melt metal, whether it’s for a small metal shop or a full-scale manufacturing line, capacity isn’t just a number on a spec sheet. It’s what dictates how much you can get done in a run, how much power you’ll use, and even how smooth your workflow stays. And as someone who’s been supplying induction furnaces for over a decade, I’ve seen so many people mix up “capacity” with a bunch of other terms, so let’s break this down straight, no jargon. Induction Furnace
First off, let’s clear the basics: induction furnaces don’t work like your old gas-fired furnace that heats up the whole chamber. They use electromagnetic induction to generate heat inside the metal itself—so the “capacity” we’re talking about is almost always based on the weight of solid metal you can load and melt in one batch. That’s the key number everyone cares about, right? But it’s not a one-size-fits-all answer. I’ve seen tiny lab units that do 5 kg (that’s just over 11 lbs) of aluminum for small casting projects, up to monster industrial furnaces that crank out 150 tons of steel per batch. The range is huge, and it all depends on what you’re melting, what you’re using the furnace for, and how much space/power you have on site.
Wait, hold on—let’s not skip the part where capacity can be tricky if you don’t specify the metal. Aluminum has a lower melting point (around 660°C, or 1220°F) and is way less dense than steel (which melts at ~1538°C, 2800°F). A furnace that holds 100 kg of aluminum will only hold like 60 kg of steel, because steel is heavier. That’s a mistake a lot of new guys make—they look at a spec that says “100 kg capacity” and try to cram in steel, then wonder why it doesn’t fit. Trust me, I’ve had so many customers call us panicking because they ordered the wrong size for their metal, just because they didn’t account for density. So right off the bat: capacity is specific to the metal you’re working with. That’s non-negotiable.
Now, let’s talk about the different types of induction furnaces, because that also changes the capacity. There’s coreless induction furnaces (the most common for melting scrap, cast iron, aluminum) and channel-type induction furnaces, which are more for holding molten metal continuously, like in foundries that run 24/7. Coreless is the one most people mean when they say “induction furnace,” so let’s focus on that first.
Coreless furnaces: Small benchtop models start at 1 kg (super small, for hobbyists or R&D), go up to 1 ton for small foundries, and then the big industrial ones top out around 40 tons for steel melting. Wait, some places say 60 tons? Yeah, but that’s for specialized stuff, not your average job shop. The channel-type ones, though, are more about holding capacity than melting—they don’t cool down much, so they’re used for maintaining molten metal between pours. A channel furnace might hold 10 tons of aluminum, for example, and that’s perfect if you’re pouring a hundred parts a day and don’t want to reheat metal every time.
But here’s the thing about what people actually want to know: how much can I melt in an hour? Because capacity isn’t just batch size—it’s throughput. A furnace with a 1-ton batch can’t melt that in 10 minutes if the power is too low. Most standard coreless furnaces have a power rating that lines up with their batch capacity: a 1-ton steel furnace will usually have around 1000 kW of power, so it can melt a full batch in about an hour. If you cram more power in, it melts faster, but you can’t just stuff more metal in unless the chamber is built for it. So throughput is a big part of “capacity” that a lot of spec sheets hide. I always tell customers: if you need to melt 5 tons of steel a day, a 1-ton batch that runs twice a day is enough, or a 500 kg batch that runs 10 times—same total, but the smaller one might save on power costs.
Wait, let’s get into the factors that dictate capacity, because if you’re buying one, you don’t just pick the biggest one. First, metal type, like we said. Then, power supply—induction furnaces run on electricity, right? The power supply (the inverter and transformer) has to be matched to the furnace’s coil and crucible. A crucible is the liner that holds the metal, by the way—usually made of refractory material like silica for aluminum, magnesia for steel. If you get a crucible that’s too big for the power, you’ll never get the metal hot enough, no matter how much you stuff in. If it’s too small, you’re wasting power and not using the space.
Then there’s your operation. Are you a small job shop that does 100 kg batches once a week, or a large foundry melting 500 tons a month? I had a customer a few months back who was a custom jewelry maker, so he needed a 5 kg gold furnace—perfect, no need for something bigger. Another was a guy who ran a small art casting studio, doing bronze, so a 50 kg furnace was exactly what he needed. I tried to upsell him a 100 kg once, but he said he didn’t have the space for the bigger unit, and that was fine. So space is another factor. The big industrial furnaces are huge—they take up whole rooms, have cranes to load scrap metal. If you’re in a small workshop, you can’t fit a 20-ton furnace, obviously.
Also, don’t forget about efficiency. A furnace that’s rated for 10 tons might actually only melt 9 tons effectively, because some heat is lost to the crucible, or the induction coil isn’t perfectly matched. The good suppliers (that’s us, by the way) will give you the “usable capacity” not just the nominal one. Nominal capacity is the number on the spec sheet, but usable is what you can actually put in without it spilling or taking too long to melt. I’ve seen competitors advertise a 20-ton furnace that’s only good for 17 tons, and that’s a bait and switch. We always tell customers up front what the usable capacity is, because we’ve been burned before by guys who came back mad because they couldn’t cram the full nominal amount in.
Wait, let’s address a common myth: induction furnaces have a maximum capacity you can’t exceed, ever. That’s true, but you also don’t want to run them at full capacity every single time. Crucibles wear out faster if you’re loading them right to the top, and power consumption goes up. A good rule of thumb is to run at 80% of the rated capacity for regular batches, and only go to 100% if you have a big rush order. That’s something I teach all our customers, because overloading a furnace shortens its lifespan, which ends up costing more in the long run.
Now, for those who are still stuck on picking the right one: let’s give some real examples, not just numbers. Let’s say you’re melting aluminum for automotive parts. A small 500 kg coreless furnace works for a 10-person shop, melts a batch in about 45 minutes, uses around 500 kW. If you’re doing steel for construction castings, a 5-ton coreless is your go-to—big enough for most small to medium foundries, easy to operate, not too expensive. If you’re doing continuous pour for things like metal bars, a channel furnace with 10 tons of holding capacity is better, because you can keep the metal molten and pour whenever you need, no waiting for melting cycles.
I should also mention that capacity can change if you’re using pre-molten metal instead of solid scrap. If you’re charging with molten metal, you can put more in the furnace, right? Because you don’t have to spend time melting solid—you just top it up. That’s another trick I share with customers: if you can re-use leftover molten metal from previous pours, you can get more total output without buying a bigger furnace. It’s one of the ways induction furnaces are way more flexible than other types.
Okay, so let’s wrap this up for anyone who’s reading this and trying to figure out their own needs. The capacity of an induction furnace isn’t just a random number—it’s dependent on what metal you’re melting, how much power you have, your workspace, and what you’re actually making. There’s no “best” capacity, only the right one for your operation.
If you’re shopping around and not sure whether a 100 kg or 500 kg furnace is right for you, don’t guess. That’s where our team comes in. We’ve helped hundreds of customers—from hobbyists to large foundries—find the exact capacity they need, no upselling, no confusing spec sheets. We’ll ask you what metal you’re working with, how many batches a day you run, how much space you have, and we’ll point you to the right furnace. No guesswork, no fine print.
If you’ve got questions about capacity, or you want to see what units we recommend for your project, just reach out to our team to talk through your needs. We’re here to make sure you get a furnace that fits your workflow, not just a big number that looks good on paper.
Rolling Mill References:
- Davis, J. R. (2001). Cast Metals: Fabrication, Technology, and Performance. ASM International.
- Campbell, J. (2000). Complete Casting Handbook: Metal Casting Processes, Techniques and Design. Butterworth-Heinemann.
- Induction Heating Association. (2019). Guide to Induction Furnace Capacity and Sizing. Industrial Heating Magazine.
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