Cost & Quoting

Motor and Generator Manufacturing Cost: What Drives Cost Per Unit and How to Quote It

A money-first breakdown of motor and generator build cost, from magnet spend to hipot rework, with the ratios estimators use to quote and where quotes go wrong.

On most fractional and integral-horsepower motors, material is 55 to 70 percent of unit cost and copper plus magnets dominate it. A 5 kg motor with 1.4 kg of copper at 11 dollars per kg is 15.40 dollars in windings before scrap, and 252 grams of N42 NdFeB at 90 dollars per kg adds 22.70 dollars. Together that is 38 dollars of active material on a motor that might sell for 95 dollars, so a 10 percent swing in the London Metal Exchange copper price moves your unit cost by roughly 1.50 dollars and quietly erases margin if your quote is fixed for a year.

Magnet spend deserves its own line because rare-earth pricing is volatile and grade choice is a lever. Dropping from N42 to N38 or switching to a bonded ferrite where torque density allows can cut magnet cost 40 to 70 percent. The Magnet Cost per Motor calculator converts grams per rotor and grade price into dollars so you can quote three magnet options side by side. Estimators go wrong by pricing magnets at spot on quote day; use a trailing 90-day average and add a 5 to 8 percent surcharge clause, because dysprosium content in high-temp grades can double the base price.

Winding labor is the largest controllable conversion cost, usually 12 to 20 percent of unit cost. The mistake is quoting winding at standard minutes and forgetting the efficiency factor. If Stator Winding Labor returns 23 standard minutes but your line runs at 82 percent efficiency, you actually pay for 28 minutes, and at a 42 dollar fully burdened labor rate that is 19.60 dollars, not 16.10. Use the Winding Scrap Cost calculator alongside it: a 4 percent winding scrap rate on a 38 dollar material stator adds 1.58 dollars of pure loss per good unit that must be recovered in the quote.

Machine and oven time convert to cost through burden rate per hour, not headcount. A varnish oven with a 110-minute cycle holding 180 stators at a 45 dollar per hour burden spreads (110/60 x 45) / 180 = 0.46 dollars per stator. The Insulation Varnish Cure Load calculator gives the batch count that sets this denominator, and under-loading the oven is a silent cost killer: run 120 stators instead of 180 and the same cycle now costs 0.69 dollars each, a 50 percent jump on a line item nobody re-examines after launch.

Test and balancing are cost centers people forget to load. At 2.08 minutes of end-of-line test and a stand burden of 55 dollars per hour, each motor carries 1.91 dollars of test cost, and the Motor Test Stand Capacity calculator tells you whether you are paying for 3 stands or 4. Rotor balancing at 9 minutes and 60 dollars per hour is another 9 dollars on a balanced-rotor SKU. Quotes that treat test as free overhead understate cost by 3 to 11 dollars per unit, which is the difference between a 12 percent and a 6 percent margin on a mid-size motor.

Rework from failed hipot is the scrap line that ambushes estimators. If 3 percent of motors fail hipot and each failure triggers a 35-minute teardown, re-varnish, and retest, the Rework from Failed Hipot calculator spreads that across good units: 0.03 x 35 minutes x 45 dollars per hour = 0.79 dollars per unit built, before the material you scrap on unrecoverable failures. World-class lines hold hipot failure near 0.5 percent; quoting to 0.5 while running at 3 percent understates conversion cost by more than 0.60 dollars and turns a profitable job into a loser at volume.

Overhead and yield stack multiplicatively, so apply them in the right order. Build your quote as material plus conversion labor plus machine burden, sum to a factory cost, then divide by first-pass yield before adding SG&A and margin. At a 94 percent rolled yield, a 78 dollar factory cost becomes 82.98 dollars of good-unit cost; layer 14 percent SG&A and a 15 percent margin and you land near 108 dollars. Estimators who add yield loss and margin as simple additions rather than divisions routinely under-quote by 4 to 7 percent, which is often the entire profit on electrification work.

A defensible quote shows the buyer the cost stack, not one number. Break out material with a copper and rare-earth escalation clause, conversion labor at actual efficiency, machine burden per unit, a named scrap and rework allowance, and yield-adjusted overhead. Tie each line to a calculator so the number is auditable: Winding Scrap Cost for scrap, Rework from Failed Hipot for test recovery, Magnet Cost per Motor for the volatile material. Buyers accept a 108 dollar quote with a visible 38 dollar material line and a stated 3 percent price-adjust trigger far faster than a flat number they cannot challenge.

Published 2026-07-01.