KEVOS® MAKEOS · Materials
Heat-Treatment Furnace Load Plan (Time, Energy, Cost)
How long will this load take to heat, how much energy will the cycle use, and what does it cost per kilogram?
Energy plan for a furnace heat-treatment cycle: energy to heat the load and its fixtures through the temperature range from mean specific heat (as the heating energy tool), heat-up time from the furnace power and the share reaching the load, standing losses during the soak, total energy, cost per load and cost per kilogram of work.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Work mass | kg | Mass of parts in the load. |
| Fixture and basket mass | kg | Mass of baskets, trays and fixtures heated with it. |
| Mean specific heat over the range | kJ/kg·K | Average specific heat between the two temperatures (about 0.6 kJ/kg·K for steel to 850 °C, including the transformation). |
| Start temperature | °C | Temperature of the load going in. |
| Set temperature | °C | Furnace set temperature. |
| Furnace input power | kW | Rated input of the furnace. |
| Share of input reaching the load while heating | % | Share of input power going into the load during heat-up (the rest heats the furnace and escapes). |
| Standing heat loss at temperature | kW | Power the furnace needs just to hold temperature empty. |
| Soak time | h | Time at temperature (from the heat-treatment specification for the section size). |
| Energy price | $/kWh | Price of electricity or fuel per kWh. |
Method and formulas
- Heat Q = (m_work + m_fixture) c_p (T₁ − T₀).
- Heat-up time = Q ÷ (P × share).
- Energy = Q ÷ share + standing loss × soak time.
- Cost per load = energy × price; per kilogram = cost ÷ work mass.
- Example: 500 kg to 850 °C takes about 2.3056 h to heat and costs 7.2167 cents per kg.
Limitations
- Mean specific heat; the real heat-up slows as the load approaches set temperature.
- Soak time must come from the heat-treatment specification for the section size.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Quote heat treatment by energy cost
- Plan furnace loading for throughput
- Compare fuller loads against more cycles
Who it is for
- Heat treaters
- Production planners
- Estimators
What you get
- Heat into the load
- Heat-up time and total cycle
- Energy and cost per load and per kilogram
Interpreting the result
- Fixture mass is pure overhead: lighter baskets and fuller loads cut cost per kilogram.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 472–480, 372–376. Topic reference; no source tables or recommended settings are reproduced.
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Open the Heat-Treatment Furnace Load Plan (Time, Energy, Cost) calculator
