Thermal gate first
150 / 180 / 220C
Use SH, UH, and AH/EH planning windows before discussing price, but lock the final class with the demag curve at operating temperature rather than the letter grade alone.
Hybrid application planner
Neodymium Magnets for Electric Motors: Fit Checker + Decision Report
Run a thermal and sourcing fit check in under 60 seconds, then use the evidence layer to decide when NdFeB is safe, when SmCo is justified, and what to validate before RFQ lock.
Published on 2026/03/24
Last updated 2026/03/24
Start with the fit check when class or coating is still open. Jump to RFQ once your input window is stable.
SH
typical max 150C
UH
typical max 180C
AH/EH
up to 220C
SmCo 2:17
commonly used for 250-350C programs
Electric Motor Magnet Fit Checker
Inputs are designed for pre-RFQ decisions. Results are deterministic and should be confirmed with FEM/load-line validation before SOP.
Recommendation output
No result yet
Set thermal window and exposure first. The checker will return material track, risk flags, and next actions.
Core conclusions before you request quotes
Most quote mismatch happens because buyers anchor on grade names but skip thermal margin, coating validation, and supply risk assumptions.
Magnet cost still matters
20-30% of motor cost
DOE Electric Drive Technologies notes NdFeB magnets still account for roughly 20-30% of total electric motor cost in today's production systems.
NdPr price moved up again
$55 -> $69/kg
USGS MCS 2026 reports the average NdPr oxide price rose from $55/kg in 2024 to $69/kg in 2025, so RFQ buffers should not assume flat raw-material pricing.
Export controls are live
2025-04-04
China's MOFCOM Announcement No.18 of 2025 added export controls on selected medium/heavy rare-earth compounds, metals, oxides, alloys, mixtures, and permanent magnet materials.
High-temp crossover is real
>150C crossover
VAC's March 2026 brochure says selected VACOMAX SmCo alloys can deliver higher energy density than selected VACODYM NdFeB above 150C. Treat that as a working-point-specific counterexample, not a universal rule.
Good fit for
- EV traction and industrial servo teams deciding between SH/UH/AH classes
- Sourcing managers who need thermal rationale before supplier shortlisting
- Programs that require corrosion + thermal evidence in the same RFQ pack
Not suitable when
- You already completed FEM + demag bench tests and only need commercial bidding
- Hotspot exceeds 350C (requires custom material engineering path)
- Application is outside rotating electric motors (different load-line assumptions)
Market and supply signals you should not ignore
These data points define procurement risk, not just macro context. Use them to decide whether you need single-lane or dual-lane RFQ planning.
Swipe horizontally on mobile to read the full table.
| Metric | Latest value | Date | Decision implication |
|---|---|---|---|
| Global REO mine output | 390,000 t REO (China 270,000 t) | USGS MCS 2026, 2025 estimate | Concentration remains high. Keep at least one contingency chemistry or class lane for high-temp programs. |
| U.S. rare-earth net import reliance | 67% of apparent consumption | USGS Rare Earths chapter, 2025 | Lead-time assumptions should include policy/logistics shock buffers, not only nominal supplier lead time. |
| Rare-earth import source concentration (U.S.) | China 71% (2021-24 average import source) | USGS Rare Earths chapter, released 2026-01 | If your grade requires Dy/Tb-rich classes, qualify at least two supply routes before tooling lock. |
| Average NdPr oxide price | $55/kg (2024) -> $69/kg (2025) | USGS Rare Earths chapter, released 2026-01 | Do not freeze long-volume contracts without a raw-material reset clause or alternate class lane. |
| China export-control trigger | Announcement No.18 added controls on selected medium/heavy rare-earth items and permanent magnet materials | MOFCOM, effective 2025-04-04 | Ask suppliers to disclose controlled-item exposure and licensing route, not just factory location. |
| Cleantech rare-earth demand trajectory | 19 kt (2024) -> 38 kt (2030 STEPS) | IEA Rare Earth Elements report, 2025-07 | Demand growth plus concentration increases quote volatility risk for long-volume contracts. |
| EV market pull | 17 million EV sales in 2024; >20 million expected in 2025 | IEA Global EV Outlook 2025 | Motor magnet programs should expect tighter allocation windows during model-launch peaks. |
Methodology and logic chain
The planner intentionally mirrors engineering handoff: thermal envelope -> material shortlist -> coating route -> validation gate -> procurement path.
Step 1: Thermal envelope gate
Map continuous and peak hotspots to SH/UH/EH/AH and SmCo boundaries before checking BHmax.
Step 2: Coercivity reserve screen
Compare the working point and demag curve at operating temperature. If thermal margin is below 15C, downgrade confidence and require early demag verification.
Step 3: Corrosion route selection
Exposure band drives coating and test load (e.g., NiCuNi baseline, epoxy for coolant/humidity), but salt-spray hours alone do not prove field lifetime.
Step 4: Launch pressure and control-lane adjustment
Aggressive prototype windows and controlled-item licensing risk increase fallback pressure and can require alternate material planning before PO.
Evidence layer and source disclosure
Each conclusion is tied to an external source and date marker. Standards pages are included to keep validation scope explicit.
Swipe horizontally on mobile to read the full table.
| Source | What we use from it | Date marker |
|---|---|---|
| USGS Rare Earths chapter (MCS 2026) | 2025 estimates: world rare-earth output 390,000 t REO, China 270,000 t; U.S. net import reliance 67%, China supplied 71% of U.S. imports (2021-24), and average NdPr oxide price increased from $55/kg (2024) to $69/kg (2025). | Released 2026-01 |
| China MOFCOM Announcement No.18 of 2025 | Effective 2025-04-04, export controls were added on selected medium/heavy rare-earth compounds, metals, oxides, alloys, mixtures, and permanent magnet materials. | Published 2025-04-04 |
| IEA Rare Earth Elements report | Cleantech rare-earth demand rises from 19 kt (2024) to 38 kt by 2030 in STEPS; top-3 refining share remains very high (97% in 2024). | Published 2025-07 |
| IEA Global EV Outlook 2025 | EV sales reached 17 million in 2024 (>20% market share) and are expected to exceed 20 million in 2025, strengthening magnet demand pressure. | Published 2025-05 |
| DOE Electric Drive Technologies roadmap (2023 consensus) | States NdFeB magnets account for roughly 20-30% of electric motor cost in today's production systems, and rare-earth-free machines usually trade off energy density, NVH, or weight. | Published 2024-06 (2023 roadmap) |
| VAC product information: VACODYM / VACOMAX | Lists NdFeB and SmCo performance windows, states NdFeB operating temperature depends on working point/coercivity, and notes selected VACOMAX SmCo alloys can exceed selected VACODYM energy density above 150C. | Published 2026-03 |
| IEC 60404-18:2025 | Defines open-circuit magnetic property measurement for permanent magnets, including self-demagnetization correction and suitability for high Hcj materials. | Published 2025-05-30 |
| IEC 60068-2-11:2021 | Defines salt mist test procedures for quality control and detection of coating discontinuities before shipment. | Published 2021-09-23 |
| ASTM B117-26 page | Confirms salt spray exposure itself does not prescribe interpretation or exposure duration, so it should not be treated as a direct field-life predictor. | Updated 2025-12-22 |
| European Commission electric motors page | Provides current EU ecodesign scope and milestone context for motors and variable speed drives, which matters when a procurement team mixes traction and industrial motor assumptions. | Accessed 2026-03-24 |
| IEC TS 60034-30-2:2016 | Covers efficiency classes for variable-speed AC motors, including PM synchronous machines not operated directly on-line, so regulatory scope should not be generalized across all motor programs. | Published 2016-05-12 |
Research snapshot updated 2026/03/24. Unknown values are intentionally marked as pending or unavailable to avoid fabricated certainty.
Material route comparison for motor programs
Use this table to discuss tradeoffs with engineering and procurement in one review instead of separate meetings.
Swipe horizontally on mobile to read the full table.
| Decision dimension | NdFeB SH/UH | GBD NdFeB EH/AH | SmCo 2:17 |
|---|---|---|---|
| Typical BHmax window | 28-53 MGOe | 34-53 MGOe | 20-33 MGOe |
| Max operating class | 150-180C | 180-220C (some >200C with high-Hcj setup) | 250-350C |
| High-temperature energy retention | Strong at 20C, but advantage can shrink as temperature rises | Better high-temp coercivity, still working-point dependent | Selected grades can overtake selected NdFeB above 150C |
| Corrosion baseline | Coating required for sustained humidity/media exposure | Coating required for sustained humidity/media exposure | Often coating-optional, but still verify mating-system corrosion |
| Rare-earth exposure objective | No, still rare-earth dependent | No, but heavy-rare-earth loading can be optimized | No, shifts to Sm/Co route rather than removing rare-earth exposure |
| Metrology requirement before class lock | IEC 60404-5 or 60404-18 + FEM/load-line check | Prefer IEC 60404-18 for high Hcj + demag correction | Same metrology + thermal cycle mechanical checks |
| Best fit scenario | Mainstream EV/servo with <=180C peaks | High-load motors with thin thermal margin | Hotspot >220C or severe thermal cycling |
Typical BHmax window
Window aligned to VAC product ranges; final value still depends on geometry and working point.
Max operating class
Supplier class ceilings are valid only with matching coercivity and load-line assumptions.
High-temperature energy retention
VAC March 2026 data shows a real counterexample: some SmCo alloys outperform some NdFeB alloys above 150C. Do not generalize that crossover beyond the disclosed working point and alloy family.
Corrosion baseline
VAC states high-cobalt SmCo can resist prolonged hot-humidity exposure better, but ASTM B117 and IEC 60068-2-11 remain screening tools rather than direct life models.
Rare-earth exposure objective
If rare-earth avoidance is the first objective, DOE roadmaps point to non-permanent-magnet alternatives with expected energy-density, NVH, or weight penalties.
Metrology requirement before class lock
Skip direct cross-supplier comparison when measurement method is not explicitly disclosed.
Best fit scenario
Validate with FEM + demag bench before volume release.
Concept boundaries and applicability conditions
Use these gates to avoid overgeneralizing catalog data into production decisions.
Swipe horizontally on mobile to read the full table.
| Condition | Preferred interpretation | Caution zone | Do not conclude yet |
|---|---|---|---|
| Thermal margin to class ceiling | >=25C: class discussion can proceed with normal validation cadence. | 15-24C: keep contingency grade lane and run early demag verification. | <15C: do not lock supplier by price only. |
| Catalog BHmax vs operating-temperature working point | Compare demag curves and working point at the actual operating temperature. | Using BHmax or Br at 20C as the main supplier-ranking metric. | Treating a better room-temperature catalog number as proof of better motor output. |
| Corrosion proof | ASTM B117 / IEC 60068-2-11 pass with defined acceptance criteria. | Salt spray pass only, but no field medium mapping. | No coating test scope or undefined acceptance criteria. |
| Data comparability across suppliers | Measurement method disclosed (IEC 60404 family) and same working point. | Method disclosed but demag correction/work point differs. | No disclosed method, only headline BHmax. |
| Efficiency or regulation scope | Confirm whether the motor is actually in scope for EU 2019/1781 or IEC TS 60034-30-2. | Using industrial IE classes as a shortcut for traction or custom servo motor decisions. | Assuming EV traction, inverter-fed PMSM, and direct-on-line industrial motors share the same compliance path. |
Thermal margin to class ceiling
Margin thresholds in this page are planning gates; supplier BH curves still decide final lock.
Catalog BHmax vs operating-temperature working point
VAC and IEC metrology sources both point to the same boundary: motor decisions fail when room-temperature catalog data replaces in-service magnetic behavior.
Corrosion proof
ASTM B117 itself does not define duration choice or field-life interpretation.
Data comparability across suppliers
Without metrology comparability, cross-quote ranking is unstable.
Efficiency or regulation scope
Regulatory scope changes the test/document path, but it does not replace the magnet working-point decision.
Known unknowns (explicitly pending)
Public benchmark price by grade class + coating + geometry
Status: No reliable open consolidated dataset
Next step: Use normalized RFQ templates and supplier-side quote evidence instead of scraped list prices.
Supplier-specific Dy/Tb loading by high-temp grade
Status: Mostly proprietary across vendors
Next step: Request disclosure windows or at least substitution risk notes in NDA-based technical review.
Universal conversion from salt-spray hours to in-field lifetime
Status: No standard one-to-one conversion
Next step: Pair salt-mist tests with application-specific coolant/humidity cycling and teardown criteria.
Public lead-time benchmarks for controlled rare-earth export items
Status: No reliable open dataset
Next step: Require suppliers to disclose controlled-item exposure, licensing responsibility, and backup origin plan in the RFQ pack.
Risk matrix and scenario outcomes
Track thermal misuse, validation misuse, and supply concentration risk in the same review cycle.
Swipe horizontally on mobile to read the full table.
| Risk | Probability | Impact | Mitigation |
|---|---|---|---|
| Thermal misclassification (using SH where AH is needed) | Medium | High | Gate by peak hotspot and keep >=15C margin before PO. |
| Coating under-validation in coolant/salt environments | Medium | High | Tie coating plan to ASTM B117 + IEC 60068-2-11 and define field-correlated acceptance criteria early. |
| Rare-earth price and availability shock | High | Medium | Maintain two qualified grade windows, add a raw-material reset mechanism, and keep one alternate material path open. |
| Export-license disruption in Dy/Tb or controlled-item lanes | Medium | High | Track control updates, ask suppliers to declare controlled-item exposure, and pre-qualify fallback class/material options before PPAP. |
Four scenario demonstrations
Scenario A: EV traction rotor, peak 170C, humid bay
Premise: Program targets high torque density with moderate lead-time flexibility.
Process: Checker selects UH track, epoxy-first coating, and medium supply risk flags.
Outcome: Action plan: UH shortlist + 500h corrosion test + backup AH quote lane.
Scenario B: Compressor motor, peak 235C
Premise: Thermal hotspot exceeds AH comfort zone in sustained operation.
Process: Checker moves to SmCo path and downgrades confidence until bench validation.
Outcome: Action plan: SmCo pilot + NdFeB redesign branch only if cooling architecture changes.
Scenario C: Industrial servo, peak 140C, aggressive cost target
Premise: Team wants lower cost without sacrificing launch reliability.
Process: Checker suggests SH track with strict demag reserve and sourcing dual-lane.
Outcome: Action plan: SH baseline quote + UH contingency quote + tolerance harmonization.
Scenario D: Existing AH design, but Dy/Tb export route is disrupted
Premise: Thermal target remains valid but one import route is delayed after a controlled-item review.
Process: Checker keeps AH as preferred lane but flags immediate SmCo and cooling-adjustment contingency lanes plus export-license checks.
Outcome: Action plan: lock dual procurement lanes + prioritize method-equivalent validation to avoid re-qualification delays.
FAQ: boundaries, validation, and sourcing decisions
Questions are grouped by decision intent so teams can move from uncertainty to executable RFQ actions.
Planning scope
Validation and risk control
Procurement execution
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