Hybrid calculator + engineering report
AFPM Core Assembly Process
Estimate cycle time and evaluate clearance risks for segmented AFPM stator assembly. Use the evidence report to review methods, tolerance limits, and RFQ readiness.
Published: July 23, 2026Canonical keyword: afpm core assembly processEngineering review: Axial Flux Core
Assembly Decisions
The estimator highlights risks related to clearance and pole count. The structural integrity of an AFPM core relies on balancing these factors with manufacturing reality.
Key Assembly Conclusions
Methodology And Mechanics
Segmented AFPM stators often rely on Soft Magnetic Composites (SMC). Unlike stamped laminations which can endure heavy interference fits, SMC is vulnerable to tensile stress and brittle fracture.
Screening practice: start RFQ discussion with a controlled slip fit and adhesive bondline, then confirm the actual gap by adhesive selection, slot data, insertion force, and cure runout.
Thermal Expansion Risk
Carrier alloy, SMC binder route, and adhesive chemistry can move differently when hot. Treat CTE and elongation as supplier-confirmed inputs before approving rigid bonding, overmolding, or interference strategies.
Evidence Ledger
| ID | Source | Used for | Review date |
|---|---|---|---|
| S1 | Axialfluxcore - SMC vs laminated axial flux core guide | Supports material route tradeoffs and why SMC stators need different assembly controls than laminated stacks. | July 23, 2026 |
| S2 | Axialfluxcore - magnetic loss testing for high-frequency AFPM | Supports the need to protect air-gap consistency and cured geometry when the magnetic circuit is assembled from segments. | July 23, 2026 |
| S3 | Axialfluxcore - manufacturing and quality controls | Supports CMM, go/no-go, AOI, and process validation controls referenced in the checklist. | July 21, 2026 |
| S4 | Axialfluxcore - technology and materials | Defines material-route boundaries; exact SMC strength, CTE, and resin data must be confirmed from supplier datasheets. | July 23, 2026 |
| S5 | Project-specific supplier material and adhesive datasheets | Required before converting screening clearances, bondline targets, TRS, shear, or CTE assumptions into release criteria. | Project-specific; confirm during RFQ |
| S6 | JMAG / Hoganas - double-sided axial flux SMC reference | Supports the material and process context for using powder-metal SMC components in axial flux machine geometries. | Accessed July 23, 2026 |
Screening Assumptions To Confirm
| Parameter | Screening value | Evidence status | Confirm before release |
|---|---|---|---|
| Cycle-time estimate | 5 minutes setup plus a segment placement term driven by OD and clearance. | Internal screening model; useful for comparing options, not quoting production takt. | Supplier time study with fixture loading, adhesive dispense, cure staging, and inspection included. |
| Clearance band | 0.02-0.50 mm input range, with warnings below 0.05 mm and above 0.35 mm. | Engineering heuristic surfaced as a boundary state, not a release tolerance. | DOE for insertion force, adhesive wet-out, cured runout, squeeze-out, and thermal cycling. |
| SMC mechanical limit | Treat SMC as more brittle than laminated steel under tensile or insertion stress. | Directionally supported by material-route differences; exact TRS or tensile value is supplier-specific. | Material datasheet, lot qualification, insertion-force coupon test, and crack inspection criteria. |
| Thermal movement | Assume carrier, SMC, and adhesive may have materially different expansion behavior. | Risk is real, but exact CTE values vary by carrier alloy, SMC binder, compaction route, and adhesive. | Supplier CTE data and representative thermal shock or thermal cycling validation. |
| Adhesive retention | Wide clearance shifts retention from geometry to bondline coverage and cured shear margin. | Process assumption; final margin depends on adhesive family, surface prep, cure, and torque load. | Lap-shear/coupon data, torque retention test, cure profile, and contamination controls. |
Assembly Method Comparison
| Method | SMC Application | Laminated Steel Application | Recommendation |
|---|---|---|---|
| Press Fit (Interference) | High-risk route for SMC unless insertion force, carrier compliance, chamfer geometry, and material strength are proven together. | Standard for laminated steel cores, handling high hoop stress. | Avoid as a default SMC route; use only after supplier force, crack, and thermal-cycle evidence supports it. |
| Slip Fit + Adhesive | Preferred screening method. Uses a controlled bondline instead of relying on metal-to-core interference. | Used when avoiding stresses that could degrade magnetic properties. | Recommended RFQ baseline for AFPM SMC stator assembly when adhesive coverage, cure, and runout are controlled. |
| Overmolding / Potting | Encapsulates the core and can decouple carrier/core movement when resin elongation, Tg, and cure shrinkage are matched. | Improves thermal transfer to cooling jackets but requires precise alignment fixtures. | Best for high-vibration automotive and severe duty cycles. |
Tolerance Stack To Verify
| Input | Why it matters | Verification method |
|---|---|---|
| Segment width tolerance | Accumulates around the circumference; can lead to the final segment not fitting. | CMM inspection of batch samples before assembly. |
| Carrier slot width | Determines the baseline clearance for adhesive bonding. | Go/no-go gauges or laser scanning on the carrier. |
| Dispensed adhesive volume | Too little risks failure; too much causes squeeze-out into the air gap. | Automated optical inspection (AOI) on dispensing robots. |
Risks And Controls
| Risk | Impact | Likelihood | Mitigation |
|---|---|---|---|
| SMC chipping during insertion | High | Medium | Use a supplier-approved slip fit, chamfered carrier slots, insertion-force limits, and post-insertion crack inspection. |
| Tolerance stack-up failure (circumferential) | High | Medium | Sort segments by width, define a closure-gap strategy, and verify accumulated position before adhesive cure. |
| Thermal cracking of SMC / Adhesive | Medium | Low | Select adhesive and carrier geometry using supplier CTE, elongation, Tg, and thermal-cycle evidence. |
| Excessive adhesive squeeze-out | Low | High | Implement automated volumetric dispensing and design small reservoirs at the bottom of the slot. |
Scenario Examples
Buyer Checklist
Confirm SMC material tensile strength and acceptable press forces.
Define maximum allowable adhesive squeeze-out near the air gap.
Establish a thermal-cycle plan based on the project duty profile.
Require runout verification after the stator is fully cured.
Review supplier capabilities for automated potting/dispensing.
FAQ
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