Heat Treat Cost

Heat Treatment Cost Estimation: How to Quote Furnace Work Per Part and Per Pound

What actually drives cost per part in heat treatment, how to build a quote that holds up, and the estimating errors that erase margin.

Heat treatment is quoted per pound or per part, and the batch nature of furnaces makes both sensitive to load fill. A cycle that costs $180 in gas, labor, and overhead spread over a full 1,200 lb load is $0.15 per pound; the same cycle at half fill is $0.30 per pound. Commercial hardening commonly runs $0.20 to $0.80 per pound depending on process, with vacuum and carburizing at the top end. Start every quote from a realistic fill assumption, then use the Heat Treat Cost per Part calculator to allocate the fixed cycle cost across actual pieces.

Energy is the largest variable cost and swings with natural gas and electricity prices. A cycle drawing 710,000 BTU at $9 per MMBTU is about $6.40 in gas alone, but atmosphere generators, endo gas, and idle-hot holding push the real figure far higher. Electric and vacuum furnaces bill on kWh: a 300 kW furnace running 8 hours at $0.11 per kWh is $264 of power. The Furnace Energy Cost calculator turns therms and kWh into dollars, and it is where volatile utility rates should be updated quarterly, not annually.

Labor and fixturing are often underbooked. Loading, unloading, racking, and coupon testing might take 1.5 hours of a $32 per hour operator's time per batch, or $48, plus a share of a metallurgist's oversight. Fixtures and baskets are consumables in disguise: a $2,000 alloy basket that survives 300 cycles adds $6.67 per cycle. Spread across 100 parts that is only 7 cents each, but on low-count high-value tooling it matters. Book fixture depreciation as a line item so it does not vanish into overhead.

Consumables include quench media, atmosphere gas, and stop-off paints. Quench oil degrades and is topped up; a $1,200 charge of oil replaced twice a year across roughly 2,000 cycles is about $1.20 per cycle plus filtration and disposal. The Quench Media Cost calculator captures make-up volume, drag-out loss on parts, and disposal. Tempering adds its own smaller cycle cost, which the Tempering Cycle Cost calculator isolates so a hardened-and-tempered quote reflects two furnace passes, not one.

Scrap is the silent margin killer because a rejected part carries all the value added before and during heat treat. If a $140 machined component cracks in quench, you lose the part plus the cycle share plus rework of the replacement. At a 2 percent scrap rate on a 100 part load of $140 pieces, that is roughly $280 of loss per batch, often more than the energy bill. The Heat Treat Scrap Cost calculator models this; quoting without a scrap allowance of 1 to 3 percent on demanding geometries is how estimators go underwater.

Overhead absorption depends on furnace utilization, and this is where quotes go wrong most often. Fixed costs, rent, maintenance, depreciation, and salaried staff, get recovered over loaded-hot hours. A furnace utilized at 45 percent must load twice the overhead per hour of one at 90 percent. If your shop rate assumed 80 percent utilization and you are actually at 50, every job is under-recovered by roughly 60 percent on overhead. Reconcile the Furnace Utilization figure against the utilization baked into your burdened hourly rate before bidding volume work.

Build the quote bottom-up: sum cycle energy, direct labor, fixture and consumable share, quench and atmosphere cost, then divide by parts at your planned fill to get direct cost per part. Add a scrap allowance, then apply the burdened overhead rate per furnace hour, then margin. For the earlier 100 gear load: roughly $6.40 gas, $48 labor, $10 consumables, $12 fixtures equals about $76 direct, or $0.76 per part, before overhead and a 2 percent scrap adder near $2.80 per part on $140 gears.

The most common estimating failure is quoting at ideal fill and running at partial fill. A furnace booked at $0.20 per pound assuming 1,200 lb loads bleeds money at 600 lb because the cycle cost is fixed regardless of charge. Either enforce minimum-lot pricing, a flat cycle charge plus a per-pound rate, or a small-lot surcharge. Second most common is stale energy rates: a quote built on last year's $4 gas evaporates when spot gas hits $9. Re-run the Heat Treat Cost per Part calculator whenever utility rates or typical fill shift by more than 10 percent.

Published 2026-07-01.