How do you calculate batch heat treat capacity?

Multiply parts per load by usable loads per shift to get gross capacity, then multiply by uptime and first-pass yield. With 250 parts × 6 loads × 88% uptime × 96% yield, good capacity is 1,267 parts per shift.

What is the difference between gross and good batch capacity?

Gross capacity (1,500 parts here) is the theoretical maximum if nothing broke and nothing scrapped. Good capacity (1,267) is what you can actually ship after 180 parts lost to downtime and ~53 to quality fallout.

How many furnace loads can I run per shift?

It depends on cycle time, load and unload time, and quench capacity. Count only loads that fully complete within the shift — a load that finishes after handoff belongs to the next shift's count.

What is a good first-pass heat treat yield?

Production hardening and case-hardening lines commonly run 95-99% first-pass yield. The 96% in the example costs about 53 parts per shift; pushing to 99% would recover most of that quality loss.

How do I increase batch heat treat capacity?

Attack the biggest loss first. Here downtime costs 180 parts versus 53 from yield, so improving uptime from 88% toward 95% returns far more than chasing the last point of yield.

Does a bigger furnace load always mean more capacity?

Only if load density doesn't hurt heating uniformity. Overpacking a load can slow soak, cause uneven case depth, and drop first-pass yield, erasing the gross-capacity gain.

Heat Treatment, Furnaces & Thermal Processing calculator

Batch Heat Treat Capacity Calculator

Batch heat treat capacity is the number of good, on-spec parts a batch furnace can deliver per shift after accounting for downtime and quality fallout. Heat treat planners and OEM buyers use it to commit realistic delivery dates instead of quoting off the furnace nameplate. The gap between gross capacity and good capacity is where money leaks: a furnace that loads 1,500 parts but only ships 1,267 good ones is losing a fifth of its output to downtime and scrap. Modeling all four levers — load size, loads per shift, uptime, and yield — shows exactly which one to attack first.

What this calculator does

Estimate good batch heat treat output per shift from parts per load, usable furnace cycles, uptime, and first-pass yield.
Use it when a batch furnace, vacuum furnace, oven, or atmosphere furnace must prove it can cover scheduled demand.
It computes good parts-per-shift by multiplying load size and loads per shift, then derating for furnace uptime and first-pass yield.

Formula used

Gross batch capacity = parts per furnace load × usable furnace loads
Good batch heat treat capacity = gross batch capacity × furnace uptime × first-pass heat treat yield

Inputs explained

Parts per furnace load: Use the accepted parts, loads, tests, or batches completed each cycle.
Usable furnace loads: Use usable cycles after warm-up, setup, transfer, maintenance, and planned stops.
Furnace uptime: Use recent uptime or availability for the same furnace, line, or test station.
First-pass heat treat yield: Use first-pass yield after inspection, hardness, case depth, profile, distortion, or release checks.

How to use the result

Use it when quoting capacity to a customer, planning a production week, or sizing whether current furnaces can absorb a new program.
It assumes uniform parts and a single furnace recipe; mixed loads with different cycle times or part counts will skew the per-shift figure.

Current U.S. benchmarks

Industrial electricity averages 8.66 cents per kWh across the U.S. (EIA, Apr 2026), up 5.5% from a year earlier. Energy-intensive steps carry this directly into unit cost.

Common questions

How do you calculate batch heat treat capacity? Multiply parts per load by usable loads per shift to get gross capacity, then multiply by uptime and first-pass yield. With 250 parts × 6 loads × 88% uptime × 96% yield, good capacity is 1,267 parts per shift.
What is the difference between gross and good batch capacity? Gross capacity (1,500 parts here) is the theoretical maximum if nothing broke and nothing scrapped. Good capacity (1,267) is what you can actually ship after 180 parts lost to downtime and ~53 to quality fallout.
How many furnace loads can I run per shift? It depends on cycle time, load and unload time, and quench capacity. Count only loads that fully complete within the shift — a load that finishes after handoff belongs to the next shift's count.
What is a good first-pass heat treat yield? Production hardening and case-hardening lines commonly run 95-99% first-pass yield. The 96% in the example costs about 53 parts per shift; pushing to 99% would recover most of that quality loss.
How do I increase batch heat treat capacity? Attack the biggest loss first. Here downtime costs 180 parts versus 53 from yield, so improving uptime from 88% toward 95% returns far more than chasing the last point of yield.

Last reviewed 2026-05-12.