Rare Earth Magnet & Motor Materials calculator
Rework Cost Calculator
Rework cost captures what it really costs to salvage rejected rare earth magnets rather than scrap them, folding in remachining labor, the fraction that is actually recoverable, and the fixed charge to re-run the nickel or epoxy recoat line. Process engineers and cost accountants in magnet and motor-material plants use it to decide whether to rework a lot, quote a customer's return, or push the batch straight to scrap and reclaim. Because sintered NdFeB is brittle and coatings are the usual failure point, a large share of 'defective' pieces can be recovered by regrinding and recoating instead of losing the expensive dysprosium-bearing alloy inside. The calculator separates the per-piece variable cost from the fixed recoat setup so you can see where the money goes.
What this calculator does
- Estimate the cost of reworking sintered rare earth magnets through regrind, recoat and re-inspection before they re-enter the motor build.
- A magnet supplier weighs whether to salvage a batch of chipped NdFeB blanks or scrap them outright.
- It computes total rework spend, per-magnet rework cost, and the split between variable remachining labor and the fixed recoat setup charge.
Formula used
- Total rework = magnets reworked x remachining rate x salvageable share + recoat setup
- Per-magnet cost = total rework / magnets reworked
Inputs explained
- Magnets reworked:
- Rework labor and remachining rate:
- Salvageable share:
- Recoat line setup charge:
How to use the result
- Use it when a magnet lot fails final coating adhesion, dimensional, or Br/Hc inspection and you must choose between reworking and scrapping.
- It does not credit the alloy value recovered from scrapped pieces, so compare its output against your reclaim-per-kilogram rate before deciding.
Current U.S. benchmarks
- The producer price index for copper and brass mill shapes stands at 559.593 (BLS, May 2026), up 76.8% from a year earlier. Quotes priced off last quarter's material cost miss this move. Global copper trades at $13,484 per tonne (IMF via FRED, May 2026).
- The U.S. has 5,397 electrical equipment and appliances establishments employing about 369,437 workers (Census County Business Patterns, 2023).
Common questions
- How do you calculate magnet rework cost? Multiply magnets reworked by the remachining rate and the salvageable share, then add the recoat setup charge. With 400 pieces at $6.50, a 70% salvageable share, and an $850 setup, that is 400 x 6.50 x 0.70 + 850 = $2,670 total.
- What is the rework cost per magnet in the example? $6.675 per piece: the $2,670 total divided across all 400 magnets sent through rework. Note this exceeds the $6.50 base rate because the fixed $850 setup is spread over the batch.
- Why is salvageable share below 100%? Not every rejected magnet survives regrinding; chips, cracks, and out-of-spec magnetic properties send some to scrap. At 70% salvageable, only 280 of the 400 pieces truly get recovered, which is why variable cost is $1,820, not $2,600.
- Rework vs scrap and reclaim — which is cheaper? Compare the $6.675 per-piece rework cost to the net loss of scrapping: new blank cost minus alloy reclaim credit. If reclaim recovers most of the rare-earth value, scrapping badly cracked pieces can beat rework.
- How do I lower the fixed recoat setup charge per piece? Batch reworked magnets so the $850 setup is amortized over more pieces. At 400 pieces it adds $2.125 each; at 850 pieces it would add only $1.00 each.
Last reviewed 2026-05-12.