Electric Melting Furnace Cost per Melt: A Practical Worksheet

Quick answer

Electric melting furnace cost per melt equals measured electricity plus allocated crucible, maintenance, labor, material loss, and downtime costs. Wattage multiplied by time estimates only electricity—and can still be wrong because a controlled heater cycles. Measure kWh at the actual operating condition and calculate cost per accepted output.

Start with two cost numbers

Track both:

1. Cost per attempted heat = total heat cost ÷ attempted heats
2. Cost per accepted kilogram = total heat cost ÷ accepted casting mass

The first helps monitor the furnace process. The second helps quote work. A cheap heat that produces rejects is not cheap production.

Use this worksheet:

Do not count recoverable sprues and runners as a total loss if they remain traceable and suitable for controlled reuse. Do not value unknown or contaminated returns as equivalent to certified feedstock.

Measure electricity instead of assuming full power

The basic upper-bound calculation is:

Rated kW × elapsed hours = maximum simple kWh estimate

An 1.8 kW nameplate operating for 0.75 hours gives 1.35 kWh only if it draws rated power continuously. A PID-controlled resistance heater may cycle, and auxiliary loads or measurement error may change the total. A suitable energy meter or circuit-level record provides a better input, used within its rating and installation requirements.

ToAuto currently lists 1400 W in the TGF3000 Product Details but 1800 W in the FAQ on the same page. That conflict is precisely why a buyer should use the unit nameplate and exact revision—not copy a web value into a cost forecast. The TAF8000 page currently lists 1800 W and a 60–70 minute manufacturer estimate for a full aluminum load at 80% fill; that still does not establish your kWh, yield, or labor.

Do not publish a universal dollar figure. Electricity prices vary by location, tariff, demand structure, tax, and date.

Allocate crucible cost by condition, not a promised cycle life

Crucibles are consumables, but a fixed life promise is not defensible without controlled conditions. Alloy, maximum temperature exposure, hold time, oxidation, flux, thermal shock, mechanical handling, storage, and inspection criteria all matter.

Use:

Crucible cost per heat = landed crucible cost ÷ documented usable heats

If a crucible is retired after a defect is found, preserve the retirement reason. If the remaining number of safe heats is unknown, do not keep using it merely to improve the spreadsheet.

Community reports range widely and are anecdotal. They are useful for identifying crucible cost as a buyer concern, not for predicting ToAuto crucible life.

Add labor and waiting honestly

Count staffed time for:

• inspection and setup;
• charge sorting and weighing;
• supervised heating;
• mold readiness;
• lifting and pouring;
• cleanup, logging, and safe shutdown;
• troubleshooting and rework.

If an operator can perform other approved work while supervising the furnace, define how labor is allocated. Do not quietly set supervised time to zero. An electric furnace should not be left unattended simply because its controller cycles automatically.

Convert loss into a mass balance

For each heat, record:

Charge = accepted casting + recoverable returns + dross/slag + retained metal + spill + unaccounted difference

Then attach a value basis to each category. For precious-metal work, an unexplained mass difference deserves investigation. For aluminum scrap, dross and contamination can dominate the apparent economics. The cost model should expose those differences rather than hiding them inside an average.

Compare equipment with sensitivity ranges

When comparing a smaller and larger furnace, vary the inputs that can change the answer:

A higher-capacity furnace can lower labor per kilogram when the full batch is needed and safely handled. It can increase cost when it produces excess metal, longer changeovers, more inventory, or poor yield. Capacity utilization belongs in the purchase decision.

Frequently asked questions

Is electricity the biggest furnace cost?

Not necessarily. Labor, crucibles, rejected castings, material loss, and downtime can exceed electricity. Measure every major component before optimizing the smallest one.

Can I calculate cost from the wattage label?

Wattage and elapsed time provide a rough ceiling only when the rating is correct and the heater runs continuously. Measured kWh from the exact unit and process is better.

Should furnace purchase price be included?

For business costing, allocate purchase, freight, installation, and other capital costs using the accounting method appropriate to your business. Keep that allocation separate from variable cost so comparisons remain clear.

Bottom line

The defensible electric melting furnace cost per melt is an evidence trail, not a marketing number. Measure energy, record crucible retirement, time supervised work, close the mass balance, and divide by accepted output. That dataset also tells ToAuto which design or support improvement would reduce customers' real cost.

References

• ToAuto TGF3000 product page
• ToAuto TAF8000 product page
• ENERGY STAR metal casting energy guide
• Community discussion: electric furnace operating cost must include consumables