| Magnetic constant used in force estimate | mu0 = 1.25663706127e-6 N A^-2 | NIST SP 959 (CODATA 2022, published 2024-05) | All theoretical pull-force estimates depend on this constant in the Maxwell-stress formula. | [S1] |
| Idealized contact-force shortcut | F approx 40 * B^2 * A (A in cm^2) | Intermag digest, 2018 | At B = 1.0 T and area = 1 cm^2, ideal force is about 40 N before derating. | [S2] |
| NdFeB Br reversible coefficient (example grade table) | -0.12% per C for N42/N52 and G45SH lanes | Arnold data table (accessed 2026-02-18) | Strength declines with temperature; calculator applies a thermal derating factor. | [S3] |
| NdFeB Hcj reversible coefficient (example grade table) | -0.75% per C for N42/N52; -0.549% per C for G45SH | Arnold data table (accessed 2026-02-18) | Coercivity margin can collapse faster than Br when temperature rises; this drives irreversible-risk screening. | [S3] |
| Example max operating temperatures by lane | N42 = 80C, N52 = 60C, G45SH = 150C | Arnold data table (accessed 2026-02-18) | Highest room-temperature strength lane can have lower thermal ceiling; grade upgrades need temperature-context checks. | [S3] |
| Magnetic-property test-method standard | IEC 60404-5 published 2015-04-16 | IEC catalog metadata | Field and demag test data in RFQs should align with recognized method standards. | [S4] |
| Permanent-magnet material specification standard | IEC 60404-8-1 published 2023-09-20 | IEC catalog metadata | Grade labels should be mapped to standard-compliant property declarations. | [S5] |
| Standard gravity used for load conversion | g = 9.80665 m/s^2 | SI conventional value | Tool converts kg loads to newtons before comparing with estimated holding force. | [S6] |
| Global rare-earth mine production (2024) | 390,000 t REO equivalent; China = 270,000 t | USGS Mineral Commodity Summaries 2025 | High-grade NdFeB sourcing remains structurally sensitive to concentration in one producing region. | [S9] |
| US import reliance for rare-earth compounds/metals (2024) | 80% net import reliance; 70% of imports came from China (2020-2023) | USGS Mineral Commodity Summaries 2025 | Lead-time and quote risk should be reviewed with a dual-lane sourcing plan. | [S9] |
| Nd oxide price signal (China FOB) | USD 134/kg (2022) -> USD 56/kg (2024) | USGS Mineral Commodity Summaries 2025 | Spot-price drops do not remove concentration risk; lock assumptions in RFQ validity windows. | [S9] |
| US rare-earth mineral concentrate output (2025) | 51,000 t REO equivalent; estimated value USD 240 million | USGS Mineral Commodity Summaries 2026 (Rare Earths chapter) | Domestic upstream output improved, but downstream sourcing resilience still needs import and policy checks. | [S12] |
| US rare-earth compounds/metals import swing (2025) | Import quantity +169% year over year; import value USD 165M vs USD 168M in 2024 | USGS Mineral Commodity Summaries 2026 (Rare Earths chapter) | Short-term price relief can coexist with dependency risk; avoid price-only sourcing decisions. | [S12] |
| US heavy rare-earth net import reliance (2025) | 100% for heavy rare-earth compounds and metals | USGS Mineral Commodity Summaries 2026 (Heavy Rare Earths chapter) | High-temperature NdFeB planning should include contingency for heavy rare-earth exposure. | [S13] |
| Heavy rare-earth import-source concentration (2021-2024) | Terbium and holmium imports reported as 100% from China; ytterbium imports 86% from China | USGS Mineral Commodity Summaries 2026 (Heavy Rare Earths chapter) | Thermal-lane sourcing can be sensitive to export controls and licensing path changes. | [S13] |
| China rare-earth export-control timeline (2025) | Controls tightened in April, expanded in October, then October additions suspended for 1 year in November while April controls remained | USGS Mineral Commodity Summaries 2026 (Rare Earths + Heavy Rare Earths chapters) | RFQ validity windows and fallback lanes should be defined before PO freeze. | [S12][S13] |
| EU CRMA strategic benchmark (2030 target) | >=10% extraction, >=40% processing, >=25% recycling, and <=65% dependence on one non-EU country | Regulation (EU) 2024/1252 (applicable from 2024-05-23, summary updated 2025-01-23) | EU-facing programs should pre-check concentration exposure in the qualified supplier mix. | [S14] |
| ECHA Candidate List status and trigger thresholds | 253 SVHC entries (2026-02-04); article obligations trigger above 0.1% w/w with a six-month notification timeline | ECHA Candidate List update and obligations pages (2026-02 to 2026-03) | Coating and additive declarations should be release gates, not post-shipment paperwork. | [S15][S16] |
| US air-transport magnetic-field threshold | >0.00525 gauss at 4.6 m is forbidden for packages | 49 CFR 173.21(d), eCFR current as of 2026-02-18 | Strong magnet assemblies can fail logistics even if force targets pass. | [S10] |
| Salt-spray standard interpretation boundary | ISO 9227 states results are not direct corrosion-life prediction in all environments | ISO 9227 summary page, accessed 2026-02-18 | Do not map spray hours directly to pull-force retention without project-specific paired testing. | [S11] |