Ferrite Arc Magnets Fit Checker and RFQ Report
Run a 2-minute ferrite arc magnets fit check for arc shape ferrite magnet RFQs, then use trade and standards evidence to choose go, conditional, or redesign. If you are evaluating an arc shape ferrite magnet , start with the fit tool below.
Source window and alias coverage
Published: May 19, 2026. Page reviewed: October 13, 2026.
Buyer search phrases for this geometry include "arc shape ferrite magnet", "arc magnetic ferrite", "arc ferrite", "arc ferrite magnet", "ferrite arc magnet", and "arc ferrite magnets".
Quarterly source refresh + policy-trigger refresh. This page review was recorded October 13, 2026; the U.S. HTS checkpoint was refreshed to Revision 21 (published October 9), and Proclamation 11012 is shown with its published July 24 end date. Other evidence keeps its individual publication/access dates in the source tables; this review does not imply that every source was rechecked.
Ferrite arc magnet fit check
Input geometry, flux, thermal, lead time, sourcing, and quality evidence depth. The result shows a screening score, its uncertainty, and a suggested next action.
Ferrite Arc Magnets Fit Tool (2-minute checker)
First-pass planning support for ferrite arc magnets (also searched as "arc shape ferrite magnet", "arc magnetic ferrite", "arc ferrite", or "arc ferrite magnet"). This does not replace simulation, pilot tests, or formal supplier qualification.
Prefilled values are an illustrative motor-rotor example. Replace them with your project data before using the result.
Result feedback
Run the checker to get a directional fit score, uncertainty note, and a practical next action.
Model range: 10-12000k pieces.
Model range: 25-260 mm.
Model range: 20-170 degrees.
Model range: 2-40 mm.
Model range: 160-500 mT.
Model range: -20°C to 220°C.
Model range: 2-20 weeks.
Quick check
Execute ferrite arc / arc magnetic ferrite fit decision in minutes
Then verify
Understand evidence, boundaries, and tradeoffs
Source freshness
Page review dated October 13, 2026
Next step
Run tool -> lock RFQ with boundaries
On this page
Start with the screening tool, then use the evidence and boundary notes to decide what to verify before an RFQ.
Key conclusions and applicability
Each conclusion includes suitability and non-suitability so users can decide quickly without overgeneralizing.
Use the fit score as a screening signal, not an approval
The 0–100 score is an uncalibrated heuristic, not a probability or validated fit rating.
Use the score drivers to prioritize drawing, magnetic-circuit, thermal, and supplier-evidence checks before award.
Suitable: Early RFQ scoping before supplier evidence is complete.
Not suitable: Design release or supplier approval without simulation, pilot testing, and qualification.
Source: Fit tool methodology and limitations shown beside the result.
Trade depth is large, but customs rows are not arc-specific proof
WITS reports China 2024 exports of US$3,236,652.39k (HS 850511) and US$502,689.89k (HS 850519).
Use trade data for liquidity context only; factory-level arc capability still needs supplier evidence.
Suitable: Commercial teams validating whether discovery depth exists before shortlisting factories.
Not suitable: Teams using customs aggregates as direct process-capability evidence.
Source: WITS/UN Comtrade rows, checked October 13, 2026.
Unit-value spread implies mixed product classes
Computed from WITS rows: HS 850511 about US$24.8/kg vs HS 850519 about US$2.8/kg.
Quote strategy must be tied to geometry, tolerance, and magnetic window, not one blended market price.
Suitable: Buyers building negotiation bands before supplier comparison.
Not suitable: Programs that benchmark all ferrite arc parts with a single price curve.
Source: Internal calculation from WITS 2024 value and quantity rows.
Thermal derating boundary is a primary execution gate
MMPA public table cites reversible Br coefficient around -0.2%/°C and Curie around 450°C.
Curie headline is not release criteria; operating thermal validation must be tied to duty cycle.
Suitable: Motor and actuator teams with explicit thermal verification plans.
Not suitable: Projects approving suppliers only from room-temperature magnetic values.
Source: MMPA Standard 0100-00 table reference, retrieved May 25, 2026.
Policy and classification timing can change landed cost quickly
USITC lists 2026 HTS Revision 21, published October 9, 2026. Proclamation 11012’s published 10% surcharge window ran through July 24, 2026; verify any extension or successor measure and current product/origin-specific duties against the live HTS and broker guidance.
RFQ validity should include revision-date and policy-trigger checkpoints; a revision notice alone does not establish an arc ferrite duty rate or classification.
Suitable: Import lanes sensitive to duty or customs policy updates.
Not suitable: Programs locking annual duty assumptions without date-controlled review.
Source: USITC HTS announcement archive (Revision 21 published Oct 9, 2026) + Federal Register Proclamation 11012, checked Oct 13, 2026.
Ferrite continuity risk exists despite rare-earth avoidance
USGS 2026 strontium chapter shows U.S. net import reliance at 100% (2025 estimate), strontium compounds apparent consumption up 16%, and celestite imports rising to 8,100 tons in 2025 from 29 tons in 2024.
Ferrite strategy still needs continuity controls and backup-lane planning.
Suitable: Teams balancing cost, continuity, and acceptable risk before award.
Not suitable: Single-lane plans that assume ferrite eliminates upstream risk.
Source: USGS Mineral Commodity Summaries 2026, strontium chapter.
Tolerance limits dictate arc magnet cost and feasibility
Planning baseline: as-sintered ceramic ferrite arcs commonly require percent-level drawing tolerances, while ground critical faces can target sub-0.2 mm windows only with extra process evidence.
Treat sub-0.1 mm ferrite arc requirements as a high-risk engineering condition unless the supplier proves gaging, grinding yield, and Cpk history on the actual radius.
Suitable: Engineering teams drawing new arc magnets for BLDC and DC motors.
Not suitable: Projects applying legacy rare-earth tolerances to ferrite substitution without review.
Source: MMPA 0100-00 dimensional-tolerance guidance + supplier capability review practice; exact limits must be confirmed on the drawing.
Suitable audience
- Teams preparing ferrite arc RFQ packs for industrial use.
- Procurement leaders balancing price, continuity, and quality risk.
- Engineering managers who need fast pre-simulation filtering.
Not suitable audience
- Users seeking final release criteria without pilot and supplier evidence.
- Retail shoppers looking for single-unit purchase advice.
- Projects where part geometry and test methods are still undefined.
Trade concentration and data-completeness layer
These customs categories provide broad continuity context; they do not isolate ferrite arc magnet geometry.
| Scope | World value / quantity | Top-3 share | Top partners | Quantity coverage | Decision use |
|---|---|---|---|---|---|
| U.S. imports HS 850511 (2024) | US$478,125.34k; quantity 9,407,080 kg | 82.76% (China + Japan + Germany) | China US$359,791.11k; Japan US$20,545.08k; Germany US$15,379.79k | Available in WITS table (kg). | Model continuity risk at supplier-country level; single-country assumptions are high-risk. |
| U.S. imports HS 850519 (2024) | US$122,766.84k | 76.46% (China + Mexico + Vietnam) | China US$58,184.41k; Mexico US$25,700.08k; Vietnam US$9,981.67k | Quantity field is blank in WITS rows for this code; no open kg denominator on this table. | Do not derive per-kg cost from this row; request quote normalization by geometry and tolerance instead. |
| China exports HS 850511 (2024) | US$3,236,652.39k; quantity 130,756,000 kg | 39.64% (Germany + U.S. + Vietnam) | Germany US$546,473.02k; U.S. US$395,313.45k; Vietnam US$341,305.94k | Available in WITS table (kg). | Shows deep global demand, but destination spread means contract terms still need lane-specific safeguards. |
| China exports HS 850519 (2024) | US$502,689.89k; quantity 177,503,000 kg | 28.12% (Vietnam + India + U.S.) | Vietnam US$55,910.03k; India US$47,487.37k; U.S. US$37,959.28k | Available in WITS table (kg). | Lower concentration than 850511 suggests mixed classes; avoid assuming one homogeneous market behavior. |
Thermal and material boundary matrix (SrFe vs BaFe)
Counterexample handling: this matrix prevents Curie-only or price-only decisions when ferrite material switching is under discussion.
| Boundary signal | Barium ferrite | Strontium ferrite | Decision rule | Source |
|---|---|---|---|---|
| Maximum service temperature (sintered ferrite) | About 250°C | About 300°C | If duty cycle approaches 200°C+, default to strontium-ferrite validation branch and require thermal-life evidence. | MMPA 0100-00 Table III-4 (retrieved May 25, 2026). |
| Reversible Br temperature coefficient | About -0.18%/°C | About -0.20%/°C | Do not compare room-temperature gauss only; include derating margin in magnet-circuit acceptance criteria. | MMPA 0100-00 Table III-4 / III-5. |
| Curie reference and remagnetization caveat | Curie about 450°C; note indicates remagnetization needed if heated above Curie point. | Curie about 450°C; same remagnetization caveat applies. | Curie number is not release limit; use service-temperature and duty-cycle pass/fail gates for production decisions. | MMPA 0100-00 Table III-4 notes. |
| Substitution caveat from commodity context | USGS notes lower maximum operating temperature and lower intrinsic coercivity than strontium ferrite. | USGS frames strontium ferrite as the preferred substitute baseline in many applications. | Treat Ba/Sr switch as a design-change event, not a procurement-only change. | USGS MCS 2026 strontium chapter (published February 2026). |
Compliance and policy cadence controls
Recheck these controls against current legal and classification guidance before shipment.
| Control point | Latest evidence | Why it matters | Execution rule | Source |
|---|---|---|---|---|
| RoHS restricted-substance scope | European Commission RoHS page states current scope at 10 restricted substances (Annex II context). | Assuming legacy 6-substance scope can produce false pass decisions at material declaration review. | Every RFQ package must list substance scope version and declaration date, not only “RoHS pass” text. | EC Environment RoHS Directive page (accessed May 25, 2026). |
| Homogeneous-material concentration thresholds | GB guidance (updated July 22, 2025) keeps cadmium at 0.01% and other listed RoHS substances at 0.1% for homogeneous material. | Threshold ambiguity causes late compliance disputes when lab reports and supplier declarations use different limits. | Bind CoA/test reports to explicit threshold units (% and ppm) per homogeneous material. | UK RoHS Regulations guidance table, section 2.11 (accessed May 25, 2026). |
| HTS revision cadence (U.S.) | USITC announcement archive lists 2026 HTS Revision 21, published October 9, 2026 (checked October 13, 2026). | Classification and landed-cost assumptions can age out within weeks, not annually. | Before PO release, log HTS revision ID + publication date and re-check broker classification; do not treat the archive row as arc-specific duty proof. | USITC HTS announcement archive (accessed October 13, 2026). |
| Temporary surcharge time-window control | Proclamation 11012’s published 10% surcharge period ran from Feb 24 through 12:01 a.m. EDT Jul 24, 2026. May 2026 CIT/CAFC documents are historical litigation records, not a current tariff-rate determination. | The same product can carry different landed-cost outcomes depending on shipment date, entry timing, plaintiff status, collection posture, appeal status, and refund rights. | For post-window shipments, do not carry the 10% rate forward from this proclamation; check the current HTS/CBP instructions and broker classification. For entries during the window, separately verify any refund or litigation issue. | Federal Register Proclamation 11012 + CIT Slip Op. 26-47 / 26-53 (date-specific historical documents; checked October 13, 2026). |
| Postal/de minimis duty workflow | EO 14388 was republished with annex on Apr 9, 2026 and links postal-item duty assessment to the temporary surcharge timeline until expiry or CBP process switchover. | Sample-lot and urgent spare shipments can bypass normal assumptions and distort quote-to-landed comparisons. | For each expedited/small lot path, log entry mode, declared origin/value fields, and duty method before approval. | Federal Register EO 14388 corrected republication (91 FR 17839, Apr 9, 2026). |
| RoHS vs REACH declaration split | ECHA candidate-list table shows 253 entries (page snapshot with February 4, 2026 inclusion date visible), while RoHS still operates on a 10-substance Annex II restriction scope. | Teams that treat RoHS compliance as full chemical compliance can miss downstream customer disclosure obligations. | Use dual-track declaration checks: RoHS threshold compliance plus REACH SVHC declaration update log per BOM revision. | ECHA candidate list + EC RoHS page (both accessed May 25, 2026). |
| RoHS legal-review recency | EC timeline shows RoHS review finalized on December 7, 2023 with targeted-amendment direction. | Programs with multi-year SOP windows need legal-watch triggers, not one-time declaration snapshots. | Set compliance refresh checkpoint at least quarterly and on every engineering-change order. | EC RoHS timeline entry (Dec 7, 2023). |
Policy trigger timeline (dated controls)
Use these dated policy controls to align RFQs and shipment decisions with the rules that apply to each entry date.
| Date window | Policy event | Decision impact | Execution action | Source |
|---|---|---|---|---|
| 2026-02-24 to 2026-07-24 | Proclamation 11012 published a temporary 10% ad valorem import surcharge window through 12:01 a.m. EDT on July 24, 2026, subject to earlier action or an Act of Congress. | The published scheduled end date has passed. Do not carry this rate forward without confirming any extension or successor measure in current HTS/CBP guidance. | For a current quote, verify the live HTS and Chapter 99 treatment by origin and entry date with a customs broker; for entries during this window, retain entry-date records. | Federal Register Proclamation 11012 |
| 2026-02-25 | EO 14389 ends certain tariff actions but explicitly states EO 14388 and Proclamation 11012 are unaffected. | Assuming all IEEPA-linked duty effects ended at once can misprice import scenarios. | Do not collapse policy states into one “ended/not-ended” label; track by document scope. | Federal Register EO 14389 |
| 2026-04-09 | EO 14388 is republished with annex (91 FR 17839), keeping postal-item duty flow tied to surcharge timeline. | Sample lots and spare shipments may follow a different duty-administration path than standard container flows. | Require entry-mode and duty-path check before using pilot-lot landed-cost data as production proxy. | Federal Register EO 14388 republication |
| 2026-05-07 | Court of International Trade Slip Op. 26-47 holds Proclamation 11012 invalid for the importer plaintiffs and enters party-specific relief. | This ruling concerned named importer plaintiffs; it is a historical, party-specific record and does not set a current general tariff rate. | For an entry made during the published window, ask a broker or trade counsel to check whether the ruling and any later orders apply to that importer and entry. | CIT Slip Op. 26-47 |
| 2026-05-12 to appeal window | CIT Slip Op. 26-53 records a Federal Circuit administrative stay of the CIT judgment and injunction while stay motions were considered. | The cited administrative stay was an appeal-stage order from May 2026 and should not be read as a current docket or collection-status update. | For any historical refund or protest question, check the current appellate docket and entry-specific CBP instructions with counsel. | CIT Slip Op. 26-53 / CAFC administrative stay reference |
| 2026-10-09 | USITC publishes 2026 HTS Revision 21. | The prior Revision 10 snapshot is no longer current; tariff assumptions need a revision-specific and shipment-specific check. | Record the current revision ID and publication date in the RFQ award sheet; confirm applicable product/origin and Chapter 99 provisions with a broker before shipment. | USITC HTS announcement pages |
Measurement and standards boundary map
Added to prevent false equivalence in cross-supplier magnetic claims when method framing differs.
| Standard | Scope | Boundary if ignored | Execution rule | Source |
|---|---|---|---|---|
| IEC 60404-8-1:2023 | Specifies minimum principal magnetic-property values and dimensional-tolerance framing for permanent magnet materials. | Grade naming may be treated as equivalent even when tolerance/property framing differs across suppliers. | Map quote claims to explicit property windows and tolerance basis before cross-supplier comparison. | IEC webstore summary page |
| IEC 60404-18:2025 | Defines open-circuit SCM measurement methods and self-demagnetizing-field correction of demagnetization curves. | Uncorrected or differently corrected curves can produce non-comparable Br/Hci claims. | Require method declaration (SCM-VSM or extraction) and correction statement in test evidence. | IEC webstore summary page |
| ASTM A977/A977M-07(2020) | Public ASTM standard list identifies this as the test method for magnetic properties of high-coercivity permanent-magnet materials. | Different hysteresigraph practices can mask method-driven spread as supplier quality spread. | Use one agreed method family in PPAP-like evidence package for final supplier ranking. | ASTM electrical and magnetic standards catalog page |
| MMPA 0100-00 (legacy reference) | States unit properties are generally not recommended as acceptance criteria and promotes load-line based acceptance methods. | Award decisions can overfit nominal grade labels and miss operating-point failures in final circuits. | Define acceptance on operating flux/load line and test setup, not only catalog grade values. | MMPA 0100-00 section 5.1 and 9.1 text |
Evidence and method
Decision method flow
Input -> score -> boundary -> action. This keeps tool output and report evidence aligned in one decision chain.
Source-backed fact table
Dated facts used by this page. Uncertain items are explicitly flagged as pending.
| Fact | Value | Date/context | Decision implication | Source | Evidence status |
|---|---|---|---|---|---|
| China export depth in permanent magnets (HS 850511) | US$3,236,652.39k; 130,756,000 kg | WITS source year 2024 (checked October 13, 2026) | Large value confirms liquidity, but does not isolate arc-segment process capability. | WITS CHN exports HS 850511 | Verified with boundary note |
| China export depth in other permanent-magnet row (HS 850519) | US$502,689.89k; 177,503,000 kg | WITS source year 2024 (checked October 13, 2026) | High quantity with lower implied unit value signals broad product mix. | WITS CHN exports HS 850519 | Verified with boundary note |
| Implied unit value spread from customs aggregates | HS 850511 about US$24.8/kg vs HS 850519 about US$2.8/kg | Computed October 13, 2026 from WITS value/quantity rows | Price benchmarks need segment-normalized quoting assumptions. | WITS China exports HS 850511 · WITS China exports HS 850519 | Verified |
| Ferrite thermal coefficients and Curie context | Reversible Br coefficient about -0.2%/°C; Curie about 450°C | MMPA public PDF snapshot (retrieved May 25, 2026) | Thermal duty-cycle tests are mandatory before release decisions. | MMPA Standard 0100-00 Table III-5 | Verified with boundary note |
| Arc gaging tolerance reference | Arc-radius window around +0.006 in / -0.006 in references | MMPA public PDF snapshot (retrieved May 25, 2026) | Tolerance controls should be explicit in RFQ and incoming QA plan. | MMPA Standard 0100-00 Table III-3 | Verified with boundary note |
| U.S. import concentration by HS row differs materially | China share in U.S. 2024 imports: about 75.25% for HS 850511 vs about 47.39% for HS 850519 | WITS U.S. import rows checked October 13, 2026 | Continuity risk should be assessed by row, not a blended assumption. | WITS USA imports HS 850511 · WITS USA imports HS 850519 | Verified |
| HTS revision cadence and classification sensitivity | USITC HTS announcement archive lists 2026 HTS Revision 21, published October 9, 2026 | USITC HTS pages accessed October 13, 2026 | Landed-cost assumptions must reference revision ID and publication date, not annual static assumptions; the revision notice alone does not establish a product-specific arc ferrite rate without classification. | USITC Harmonized Tariff announcement archive | Verified with boundary note |
| Arc-specific duty impact from the current HTS revision | This page does not determine a current duty rate for a ferrite arc magnet; origin, product classification, and applicable Chapter 99 measures must be checked for the shipment | Boundary recorded October 13, 2026 | Keep landed-cost impact pending until the current HTS entry and shipment-specific origin/classification are confirmed with a customs broker. | USITC archive boundary note | Pending |
| Temporary import surcharge window under U.S. policy trigger | Proclamation 11012 set a 10% surcharge for entries from Feb 24 through 12:01 a.m. EDT Jul 24, 2026, unless earlier action or an Act of Congress changed the period | Published February 25, 2026; scheduled end date elapsed July 24, 2026 | Do not carry this proclamation’s 10% rate forward as a current assumption; check the live HTS/CBP instructions and shipment-specific classification for any current duties. | Federal Register Proclamation 11012 | Verified with boundary note |
| Litigation status for Proclamation 11012 surcharge | Historical record: CIT Slip Op. 26-47 addressed the proclamation on May 7, 2026 for the importer plaintiffs; Slip Op. 26-53 recorded a Federal Circuit administrative stay on May 12 while stay motions were considered. | Court documents dated May 7 and May 20, 2026; this summary is not a live appellate-docket status | For entries made during the published window, collection, refund, and appeal questions remain shipment- and party-specific; verify the docket and obtain broker/legal advice. | CIT Slip Op. 26-47 and Slip Op. 26-53 | Verified with boundary note |
| De minimis postal-duty path was republished with annex details | EO 14388 was republished on April 9, 2026 (91 FR 17839) and ties postal-item duty assessment to the surcharge timeline until expiry or CBP new entry process effective date | Federal Register corrected republication dated April 9, 2026 | Small-lot and sample logistics assumptions should be reviewed against current entry workflow. | Federal Register EO 14388 republication | Verified with boundary note |
| RoHS restricted-substance scope and threshold anchors | Current scope remains 10 restricted substances; homogeneous-material thresholds commonly used are cadmium 0.01% and others 0.1% | EC RoHS page + UK RoHS guidance snapshot (accessed May 25, 2026) | Material declaration quality gates must be included before lot release. | EC RoHS page and UK RoHS section 2.11 table | Verified |
| U.S. strontium reliance context | Net import reliance listed at 100% (2025 estimate) | USGS Mineral Commodity Summaries 2026 (February 2026) | Arc ferrite sourcing still needs continuity controls and fallback lanes. | USGS MCS 2026 strontium chapter | Verified |
| Strontium end-use linkage to ferrite magnets | USGS 2025 U.S. consumption estimate: ceramic ferrite magnets accounted for about 14% of strontium end uses | USGS Mineral Commodity Summaries 2026 (published February 2026) | Ferrite sourcing strategy must include upstream strontium continuity controls. | USGS MCS 2026 strontium chapter | Verified |
| Strontium volume shock signal in 2025 | USGS reports apparent consumption of strontium compounds up 16% in 2025 and celestite imports up to 8,100 tons from 29 tons in 2024 | USGS Mineral Commodity Summaries 2026 (published February 2026) | Continuity models should include upstream demand and logistics shock scenarios, not only price trend assumptions. | USGS MCS 2026 strontium chapter | Verified |
| RoHS and REACH cadence are not the same control plane | ECHA candidate list table shows 253 entries and latest inclusions dated February 4, 2026 | ECHA candidate-list page snapshot accessed May 25, 2026 | RoHS pass text alone is insufficient for many B2B declarations; REACH SVHC watch must run in parallel. | ECHA candidate-list table | Verified with boundary note |
| Measurement-method boundary for permanent-magnet properties | IEC 60404-18:2025 defines open-circuit SCM methods and requires correction of self-demagnetizing field when deriving demagnetization curves | IEC publication date February 20, 2025; page accessed May 25, 2026 | Cross-supplier Br/Hci comparisons are weak unless test method and correction approach are declared. | IEC 60404-18:2025 summary page | Verified with boundary note |
| Legacy standard boundary on acceptance criteria | MMPA 0100-00 states unit material properties should not be used as acceptance criteria for finished magnets and recommends load-line/operating-flux-based specification | MMPA PDF snapshot accessed May 25, 2026 | RFQ should define operating-point acceptance and test method, not grade label only. | MMPA 0100-00 section 5.1 / 9.1 context | Verified with boundary note |
| USGS substitute boundary between barium and strontium ferrite | USGS notes barium ferrite has lower maximum operating temperature and lower intrinsic coercivity than strontium ferrite | USGS Mineral Commodity Summaries 2026 (published February 2026) | Material substitution decisions should be treated as engineering changes, not quote-only changes. | USGS MCS 2026 strontium chapter | Verified with boundary note |
| Arc-only customs segmentation | No reliable open-data code cleanly isolates arc ferrite magnet transactions as a standalone global customs class | Status as of May 25, 2026 | Factory-level qualification evidence remains mandatory. | Open-data boundary based on HS taxonomy scope | Pending |
| Quantity coverage gap in U.S. import HS 850519 rows | WITS 2024 U.S. import table for HS 850519 shows trade value, but quantity field is blank in partner rows | Table accessed May 25, 2026 | Per-kg benchmarking cannot be derived from this row without supplemental source data. | WITS USA imports HS 850519 table | Pending |
| Ferrite arc magnet manufacturing tolerances | Planning baseline: as-sintered arcs are usually percent-tolerance parts; sub-0.2 mm ground features require drawing-specific confirmation. | Reviewed June 24, 2026 against MMPA tolerance guidance and supplier-capability practice | Avoid specifying rare-earth-like tolerances on brittle ferrite arcs unless gaging method, grinding yield, and lot-level capability evidence are available. | MMPA dimensional guidance boundary | Verified with boundary note |
| Ferrite raw material cost structure vs rare-earth stability | USGS reports 2025 U.S. strontium-compound apparent consumption up 16%; the June 24, 2026 review found no authoritative public arc-magnet cost index. | USGS MCS 2026 plus open-data boundary review on June 24, 2026 | Ferrite avoids rare-earth input dependence, but strontium demand, energy, grinding yield, and logistics still need quote-level sensitivity checks. | USGS strontium chapter + cost-index boundary | Verified with boundary note |
Tool and geometry boundaries
Arc geometry window
Tolerance stack focus
Thermal boundary signal
Boundary table used by the fit tool
| Input field | Planning window | Why it matters | Failure mode if ignored |
|---|---|---|---|
| Annual demand (k pcs) | 10-12,000 | Very low and very high volumes have different economics and quality control burden. | Quote strategy can be misaligned with real production cadence and supplier setup cost. |
| Arc geometry (OD / angle / thickness) | OD 25-260 mm, angle 20-170°, thickness 2-40 mm | Geometry complexity drives tooling stability and reject risk. | Nominal grade passes but dimensional instability causes pilot-to-mass drift. |
| Target air-gap flux | 160-500 mT | Higher flux targets tighten feasible ferrite window and can force grade/material fallback. | Program locks into infeasible magnetic targets and triggers late redesign. |
| Operating temperature | -20°C to 220°C | Thermal derating is one of the most common hidden causes of field performance loss. | Room-temperature validation passes while field duty fails at heat load. |
| Lead-time target | 2-20 weeks | Aggressive schedules often reduce evidence depth and increase process escape risk. | Supplier award happens before process capability is fully validated. |
| Quality evidence depth | CoA / Cpk1.33 / PPAP-like package | Evidence depth controls decision confidence more than brochure claims. | Late discovery of process instability after commercial commitment. |
Evidence-to-tool translation: why the checker changes score
Page review date: October 13, 2026. This table connects source-backed boundaries to the score output so the tool remains auditable, not a black-box recommendation.
| Tool decision point | External evidence | Boundary applied to tool | Invalid shortcut | Minimum proof before award |
|---|---|---|---|---|
| Geometry and tolerance score | MMPA 0100-00 states dimensions and tolerances must be defined on the drawing and agreed before order acceptance; individual manufacturers have different tolerance capability. | The checker treats precision tolerance as higher risk unless quality evidence depth increases to Cpk/PPAP-like proof. | Using catalog grade text or sample photos as proof that OD, arc angle, radial thickness, and assembly gap will hold in mass production. | Drawing-controlled critical dimensions, gage method, first-article results, and lot-level Cpk or dimensional history for the quoted geometry. |
| Flux and magnetic-property confidence | ASTM A977/A977M says cut specimens may not exactly represent the original magnet and different test systems may not yield identical results; IEC 60404-18 requires correction of self-demagnetizing-field effects for open-circuit SCM curves. | The checker keeps high-flux and precision cases conditional until the supplier declares test method, sensing position, and correction basis. | Comparing two supplier Br/Hci curves as equal when one is open-circuit corrected data and the other is finished-part or closed-circuit data. | Test method family, fixture/circuit condition, Hall probe or coil position, calibration basis, and correlation between sample curve and finished arc performance. |
| Thermal derating score | MMPA frames thermal values as design guidelines, not acceptance criteria; irreversible losses depend on material, geometry, and circuit. | Operating temperature above the normal window reduces score and pushes users toward duty-cycle validation, not Curie-number approval. | Approving a ferrite arc on room-temperature gauss readings because Curie temperature is far above application temperature. | Duty-cycle thermal test, demagnetization margin at hot condition, and pass/fail limits tied to the assembled magnetic circuit. |
| Sourcing and continuity recommendation | USGS MCS 2026 lists U.S. strontium net import reliance at 100% and reports 2025 celestite imports rising sharply, while WITS customs rows still do not isolate arc geometry. | Single-lane or trader-only sourcing receives lower confidence when annual demand, compliance scope, or continuity penalty is high. | Treating ferrite as supply-risk-free because it avoids rare-earth magnets, or treating HS aggregates as supplier capability proof. | Named factory, reserve-lane plan, material declaration path, and pilot-lot acceptance tied to the actual arc drawing. |
| Lead time and evidence-depth tradeoff | MMPA notes statistically valid sampling for inspection/testing unless otherwise agreed; accelerated schedules commonly compress sampling and root-cause loops. | Lead times below the normal planning band reduce score unless scope is low-risk and evidence already exists. | Accepting an expedited quote as equivalent to a qualified production plan without confirming inspection depth. | Sampling plan, control plan, agreed acceptance limits, shipment-date policy checkpoint, and recovery path for first-lot rejects. |
Options, tradeoffs, and fallback paths
Grade/force-density tradeoff visual
Sourcing-path split visual
Decision comparison table
Use this table for scenario decisions, not as a universal standards-conversion chart.
| Option | Decision signal | When to use | Main tradeoff | Fallback path |
|---|---|---|---|---|
| Standard ferrite arc baseline (Y35-like window) | Balanced path for many motor and actuator programs when geometry and thermal boundaries are manageable. | Cost and continuity matter, and package constraints are not ultra-compact. | Less magnetic headroom versus higher-energy alternatives. | Open a parallel Y40+ or NdFeB branch when flux and package constraints tighten. |
| Higher ferrite class push (Y40-like) | Extends ferrite performance before switching chemistry. | Need incremental force-density increase without full rare-earth switch. | Narrower process window and stricter QC evidence requirement. | Keep dual-material pilot plan until thermal and dimensional stability is proven. |
| Trader-mediated sourcing path | Fast quote handling but weaker direct process visibility. | Short cycle and low complexity with clear fallback plan. | Higher risk of evidence gaps during capability or root-cause review. | Force named-factory traceability and measurable lot-level evidence in contract terms. |
| Direct or dual-factory path | Best for process control and continuity under medium/high risk programs. | Programs with tight tolerance, compliance gates, or continuity penalties. | Higher onboarding overhead and qualification workload. | Use phased dual-source: one primary lane plus a validated reserve lane. |
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Risks and mitigations
Risk matrix
Scenario switch trigger
Risk register with mitigations
| Risk | Probability | Impact | Trigger | Mitigation |
|---|---|---|---|---|
| Conflicting requirements across repeat RFQs | Medium | High | Separate quote requests use different drawing revisions or acceptance criteria. | Use one controlled drawing revision and align tolerances, test methods, and compliance evidence across quote requests. |
| Geometry tolerance drift during scale-up | Medium | High | Pilot lot passes but mass lot shows OD/angle stability drift. | Lock gaging method, dimensional Cpk targets, and incoming inspection criteria before award. |
| Thermal derating underestimated in release decisions | Medium | High | Room-temperature checks used as sole acceptance gate. | Add duty-cycle thermal test and demag-margin checkpoints before PO freeze. |
| Landed-cost assumptions stale vs policy timeline | Medium | Medium | Duty model built from outdated HTS revision or policy notice state. | Record revision/date in quote sheet and revalidate before shipment release. |
| Supply continuity overconfidence in ferrite path | Medium | Medium | Single-lane sourcing with no strontium continuity controls. | Maintain dual-lane qualification and material/substitution contingency plan. |
| Evidence depth mismatch with compliance scope | Medium | High | Automotive or regulated use-cases awarded on CoA-only evidence. | Escalate to PPAP-like evidence package and gated release checklist. |
Boundary conditions and execution rules
If these boundaries are not explicitly locked in RFQ and testing, treat tool output as preliminary only.
| Topic | Boundary condition | Risk if ignored | Execution rule | Source |
|---|---|---|---|---|
| Standards interpretation boundary | Legacy grade naming and current certificate practice are not always one-to-one mappings. | Label-only comparisons can produce false equivalence between suppliers. | Bind RFQ to explicit magnetic-property windows and test conditions. | MMPA reference + supplier certificate review practice |
| Measurement-method boundary | Magnetic-property values are method-dependent; open-circuit data may require self-demag correction before comparison. | Cross-supplier Br/Hci benchmarks can look comparable while actually reflecting different test setups. | Require method family + correction method disclosure (IEC 60404-18 context) in supplier evidence packs. | IEC 60404-18:2025 public summary + ASTM method list |
| Thermal boundary | Curie reference is not the same as application operating approval limit. | Field performance loss despite room-temperature pass. | Approve only after duty-cycle thermal validation with clear pass/fail margins. | MMPA Table III-5 |
| Customs classification boundary | Public HS/HTS rows can signal context but cannot guarantee final broker classification outcomes. | Unexpected landed-cost drift after contract terms are locked. | Require broker classification checkpoint and revision-date log before shipment release. | USITC HTS revision cadence and customs practice |
| Compliance boundary | RoHS declarations can become stale when legal review updates or BOM changes occur. | Lot release delays or audit failures near shipment window. | Attach declaration version, threshold basis, and review date to each part number + lot. | EC RoHS page + implementation guidance table |
| Regulatory-scope boundary | RoHS 10-substance threshold compliance and REACH SVHC declaration obligations are separate control layers. | Programs may pass internal RoHS checks but fail customer or region-specific chemical disclosure requirements. | Operate dual declaration logs: RoHS threshold basis + REACH candidate-list watch per BOM change. | EC RoHS page + ECHA candidate list table |
| Macro data boundary | Trade aggregates do not represent supplier-level reject rate or process consistency. | Award decisions based on market size instead of real capability evidence. | Treat macro trade signals as context only, then validate supplier process evidence directly. | WITS customs aggregates and open-data scope limits |
| Data completeness boundary | Public trade rows can have missing quantity fields (for example U.S. HS 850519 in 2024 WITS import table). | Per-kg pricing models can be built on nonexistent denominators and misprice RFQ strategy. | When quantity is blank, do not compute unit values; switch to normalized RFQ comparison templates. | WITS USA imports HS 850519 table |
Acceptance traps: what the public evidence does not prove
These are the main false-confidence paths reviewed in the October 13, 2026 review. They are marked as limits, not conclusions.
| Trap | Why it fails | Reliable alternative | Source basis |
|---|---|---|---|
| Grade-label trap | MMPA explicitly treats listed material properties as descriptions, not finished-magnet inspection criteria. | Specify operating flux/load-line or application circuit acceptance in the drawing and RFQ, then require supplier evidence against that condition. | MMPA 0100-00, sections 5.1 and 9.1 context. |
| Specimen-to-part trap | ASTM A977 warns that a specimen cut from a larger magnet may not exactly represent the original sample and must be interpreted against part performance history. | Correlate material-characterization coupons with finished arc checks and field-relevant assembly tests. | ASTM A977/A977M-07(2020), Significance and Use 4.2. |
| Method-equivalence trap | ASTM notes different test systems can produce different results; IEC 60404-18 separates SCM-VSM and SCM-extraction methods and requires demag-field correction. | Request the method family, fixture/circuit condition, correction method, and sensor location before ranking supplier curves. | ASTM A977/A977M 4.3 and IEC 60404-18:2025 summary. |
| Curie-number trap | MMPA says thermal values are design guidelines and irreversible temperature characteristics depend on material, geometry, and circuit. | Use hot-condition circuit performance, demagnetization margin, and thermal cycling as release gates. | MMPA 0100-00, section 5.2. |
| Customs-aggregate trap | WITS/HS rows show macro trade context but do not identify arc geometry, manufacturing route, or reject-rate outcomes. | Use customs rows for liquidity only, then qualify named factories with drawing-level samples and lot evidence. | WITS HS 850511/850519 scope boundary. |
Example decisions and next steps
These are illustrative scenarios with hypothetical inputs. They do not represent customer results, measured magnet performance, or supplier qualification outcomes.
Scenario A: Mid-size motor refresh under cost pressure
Setup: OD 90 mm, arc 58°, thickness 11 mm, 320 mT target, 280k annual demand, 8-week lead-time target.
Tool outcome: Strong or conditional depending on quality-depth and sourcing-path selections.
Recommended action: Use ferrite arc baseline RFQ and require lot-level capability evidence before mass launch.
Scenario B: Compact actuator with high flux target
Setup: OD 42 mm, high flux target near upper band, tight package margin.
Tool outcome: Conditional or low due to force-density and thermal window tension.
Recommended action: Run parallel architecture path with higher-grade ferrite or alternative material.
Scenario C: Fast re-source after lead-time disruption
Setup: Existing geometry fixed; target lead time below 5 weeks; trader path initially considered.
Tool outcome: Score drops due to schedule pressure and reduced evidence depth risk.
Recommended action: Switch to direct/dual-source plus minimum quality evidence gates before award.
Scenario D: Compliance scope upgraded mid-cycle
Setup: Program shifts from standard industrial scope to regulated market requirement.
Tool outcome: Conditional state with explicit warning on evidence-depth mismatch.
Recommended action: Escalate to PPAP-like documentation and refresh material declarations before release.
Ferrite arc magnet FAQs
Choosing a ferrite arc magnet
Using the fit tool
Sourcing, compliance, and risk
Evidence limits and next steps
Known unknowns (explicitly marked)
This page avoids false certainty. Where evidence is weak, we keep only minimum executable continuation paths.
| Question | Current status | Decision impact | Minimum executable path |
|---|---|---|---|
| What is the publicly verifiable cross-supplier Cpk distribution for ferrite arc OD/angle tolerances? | No reliable open dataset with consistent method and segment scope was found. | Cannot claim market-average process capability with high confidence. | Request supplier-side Cpk evidence by critical dimensions and lot history before tooling freeze. |
| Is there a public, transaction-grade arc-ferrite price index normalized by geometry and tolerance? | No authoritative open index identified; listings are mostly quote-driven catalogs. | Unit-price comparisons can be distorted by hidden scope differences. | Use normalized RFQ templates and compare total landed cost with identical scope assumptions. |
| Can customs rows isolate arc ferrite magnet segment performance directly? | No standalone global customs row isolates this segment in open trade datasets. | Macro-demand signals cannot replace supplier qualification evidence. | Combine customs context with drawing-level process audit and pilot acceptance records. |
| Can we compute stable U.S. per-kg benchmarks from both permanent-magnet HS rows? | Not fully. U.S. HS 850519 import rows in WITS 2024 expose value by partner but leave quantity fields blank (checked October 13, 2026). | A single blended US$/kg benchmark would overstate precision and can bias quote negotiation. | Use HS 850511 per-kg only as directional context and rely on geometry-normalized RFQ comparisons for 850519-like scope. |
| Can all policy claims be validated from machine-readable public pages at run-time? | Partially. This review checked the Federal Register text, dated CIT opinions, and USITC Revision 21 announcement. The page does not determine current tariff treatment, product classification, or live appellate/refund status. | Policy references may need manual confirmation checkpoints before shipment-release decisions, especially where Proclamation 11012 surcharge exposure is material. | Treat USITC revision archive + Federal Register + CIT document IDs as primary checkpoints, then add broker/legal sign-off before final award. |
Sources and update dates
Page review recorded October 13, 2026; each source row retains its own publication or access date. Use these links for direct verification during quarterly and policy-trigger updates.
| Source | Supports | Update/publication time | Link |
|---|---|---|---|
| WITS / UN Comtrade (HS 850511, 850519) | Trade depth, quantity context, and unit-value spread anchors for market liquidity discussion. | 2024 trade year rows checked October 13, 2026. | Open source |
| USITC HTS announcement archive | Revision cadence for duty/classification checkpointing in landed-cost planning. | Accessed October 13, 2026; 2026 HTS Revision 21 was published October 9, 2026. | Open source |
| Federal Register policy documents (Proclamation 11012, EO 14389, EO 14388) | Published time window for Proclamation 11012 and dated de minimis/postal duty workflow references. | Publication dates Feb 25 and Apr 9, 2026. | Open source |
| U.S. Court of International Trade Slip Op. 26-47 and Slip Op. 26-53 | Historical, party-specific ruling and administrative-stay events; not a live appellate or tariff-rate status. | Slip Op. 26-47 dated May 7, 2026; Slip Op. 26-53 dated May 20, 2026; checked October 13, 2026. | Open source |
| MMPA Standard 0100-00 public PDF | Ferrite thermal/tolerance context plus legacy guidance that unit properties should not be acceptance criteria. | Retrieved May 25, 2026 (legacy reference standard). | Open source |
| USGS Mineral Commodity Summaries 2026 (Strontium) | Upstream continuity risk context, import-reliance signal, and 2025 demand/volume shock data. | Published February 2026. | Open source |
| European Commission RoHS Directive page | Current restricted-substance scope, review timeline, and implementation references. | Page snapshot accessed May 25, 2026. | Open source |
| UK RoHS regulations guidance (section 2.11) | Homogeneous-material threshold table (cadmium 0.01%; other listed substances 0.1%) for execution checklists. | Guidance updated July 22, 2025; page accessed May 25, 2026. | Open source |
| ECHA Candidate List table (REACH SVHC) | SVHC cadence checkpoint to separate REACH disclosure risk from RoHS threshold compliance. | Page snapshot accessed May 25, 2026 (shows 253 entries and Feb 4, 2026 inclusion date on listed items). | Open source |
| IEC 60404-8-1:2023 and IEC 60404-18:2025 summary pages | Measurement-method comparability and magnetic-property specification boundaries. | Publication dates Sep 20, 2023 and Feb 20, 2025; pages accessed May 25, 2026. | Open source |
| ASTM electrical and magnetic standards catalog | Test-method anchors (A977/A977M, A1054) for high-coercivity magnets and ferrite material specification context. | Page snapshot accessed May 25, 2026. | Open source |
Adjacent decision pages
Use these pages when you need deeper factory, market, or regional execution context after the general ferrite arc decision.
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