Induction Furnace Melt Energy Cost Per Ton Calculator
Melting is often the largest single conversion cost in a foundry and the least measured. This calculator starts from the physics of heating metal, adds your furnace efficiency, holding practice, losses and refractory, and gives you a cost per ton to compare with the meter.
Your numbers
Added heat for higher tapping temperatures. About 0.2 kWh per short ton per deg C for ferrous metals.
Share of input energy that ends up in the metal. Depends on frequency, coil condition, lid practice and heat size.
Power drawn to hold the bath at temperature while waiting for pour.
Include demand charges spread over the kWh you use.
Your results
Theoretical energy values are approximate enthalpy figures for typical alloys. Use measured kWh per ton from your furnace meter to calibrate the efficiency input.
Energy and melting cost per ton vs furnace efficiency
Sweeps Furnace electrical and thermal efficiency from 45 to 90, holding your other inputs fixed.
Link furnace meter data to heat records
Optional review of how melt energy, charge sheets and ERP heat records could be joined on your own servers.
Optional. The tool and every export work without this. No spam.
How to use the calculator
Pick the metal family, then adjust superheat if you tap hotter than the base value. Enter furnace efficiency, ideally from a measured kWh per ton on a normal heat, and the metal per heat. Add holding power and time, since waiting for the ladle burns energy without adding melting progress. Enter electricity price, charge cost, melt loss and refractory cost per ton. The result separates energy, loss and lining cost. Run it for a full day plan, a short heat and a cold start to see how much holding practice matters.
The method
Energy to melt is the sensible heat from ambient to the liquidus plus latent heat plus superheat. For typical alloys that sums to a few hundred kilowatt hours per short ton. Actual input is the theoretical value divided by efficiency, so a furnace at 70 percent needs about 1.4 times the theoretical energy. Superheat adds roughly the specific heat times the temperature rise. Holding energy is holding power times time, divided by the heat size. Melt loss cost is the charge cost of metal that never reaches the ladle, expressed per ton of good metal.
- Melting kWh/ton = (theoretical + superheat x 0.2) / efficiency
- Holding kWh/ton = kW x minutes / 60 / tons per heat
- Loss cost = charge cost x loss / (100 - loss)
Reading the result and common mistakes
Compare the calculated kWh per ton with your meter. A large gap points to low efficiency, long holds, a cold start, or lost lid time. Do not forget that a small heat in a large furnace is far less efficient than a full one. Typical mistakes include using the nameplate power rather than the metered energy, ignoring demand charges, and comparing aluminum and iron on the same basis. If your cost per ton is higher than a similar shop, look at holding and heat size before anything else.
Frequently Asked Questions
How many kWh does it take to melt a ton of iron?
Practical coreless induction practice is commonly cited in the range of a few hundred to roughly 600 kWh per short ton once efficiency and holding are included. Measure your own furnace, because lining condition, heat size and superheat move the number significantly.
Why does heat size matter?
A fixed amount of energy goes to holding and to losses through the lid and lining. Spread over a small heat, those losses raise kWh per ton. Running the furnace closer to full capacity usually reduces energy cost per ton.
Does superheat matter that much?
Each additional degree adds a small energy amount, but a large overshoot also increases refractory wear, metal loss and fade of treatment alloys. Tapping at the temperature the pour needs, not hotter, is a simple saving.
Where do I find the efficiency?
Divide the theoretical energy for your metal by the metered kWh per ton on a normal heat. If you do not meter, use a conservative value and update it when furnace power data becomes available.
If you want melt records, meter data and charge sheets combined into a live cost per ton, we can build that on your own servers.
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