Magnetic Rotor Assemblies — Ready to Install
Engineered magnetic assemblies for motors, pumps and specialized industrial systems — from individual magnets to validated, ready-to-install rotors. Magnets bonded or insert-molded onto shafts and lamination stacks, magnetized, dynamically balanced, and flux-verified.
For Procurement
MOQ, lead time, packaging and commercial terms — go straight to a quotation.
Discuss Your Assembly →For Engineering
Grades, drawings, process data and design support for your DFM review.
Magnet Design Guide →For Quality / SQE
Certificates, inspection planning, traceability and PPAP / FAI support per project.
Certificates & Documentation →What Goes Into a Rotor Assembly
Every component, from the magnet grade to the balancing plane, is engineered and verified as one system.
Magnets
NdFeB / SmCo / bonded — grade matched to temperature and performance spec
Shaft
Stainless, carbon steel or Alloy 42 — machined and ground to ±0.005 mm
Lamination Stack
Silicon steel 0.2–0.5 mm — die-cast or interlocked
Bonding / Overmold
High-temp epoxy, anaerobic or insert-molding — shear-tested
Sleeve (optional)
Stainless or carbon-fiber containment for high surface speeds
Validation
Magnetization, flux signature, runout and dynamic balance
Why Buy Complete Rotor Assemblies?
Magnet handling, bonding, magnetizing, and balancing are specialized processes — outsource them to us and focus on your motor winding and final assembly.
- ✓No magnet handling on your line — we deliver magnetized, balanced rotors — safety and quality improve immediately
- ✓100% flux verification — every rotor tested for pole flux and signature — no weak poles reach your customer
- ✓Dynamic balancing included — G2.5 as standard, G1.0 on request — your motor runs smoother and lasts longer
- ✓One supplier for magnets + machining — shafts, laminations, magnets, and coatings from one quality system
Applications
| Application | Typical Spec | Why This Material |
|---|---|---|
| BLDC Motor Rotors | N42SH arc segments on lamination stack | Efficient, compact motor cores |
| Pump Rotor Assemblies | Overmolded magnets on stainless shaft | Hermetically sealable wet rotor designs |
| Compressor Rotors | SmCo segments for high-temp | Refrigeration and HVAC compressors |
| Fan Rotors | Injection-molded ring magnets | High-volume cooling fan production |
| Automotive EPS Rotors | N48UH with high-retention adhesive | Steering systems needing extreme reliability |
Rotor Assembly Specifications
Typical capabilities — send your drawing for a specific quote.
| Parameter | Capability | Notes |
|---|---|---|
| Magnet materials | NdFeB N35–N54, SmCo 1:5/2:17, bonded NdFeB | Grade matched to your temp and performance spec |
| Shaft materials | Stainless 304/316/416, carbon steel, Alloy 42 | Machined and ground to ±0.005mm |
| Lamination stacks | Silicon steel 0.2–0.5mm | Die-cast or interlocked stacks |
| Bonding | High-temp epoxy (180°C), anaerobic, or overmolding | Shear-tested per lot |
| Magnetization | Radial, diametric, multi-pole, skewed | Verified per pole on 100% of production |
| Balancing | G2.5 standard, G1.0 available | Two-plane dynamic per ISO 21940 |
| Runout | ±0.01mm TIR on magnet OD | Ground and 100% inspected |
Assemblies We Build
Rotor Assemblies
Magnets on shaft / lamination stack — balanced and ready to install.
Halbach Arrays
One-sided, uniform-field arrays engineered to your air-gap target.
Overmolded Magnets
Insert-molded magnets for sealed rotors and harsh environments.
Couplings & Custom
Magnetic couplings and custom assemblies built to your drawing.
The Five Controls That Define Assembly Quality
Magnetization
Radial, diametric, multi-pole or skewed — verified per pole on production assemblies.
Bonding
High-temp epoxy or overmolding; shear strength tested on production samples.
Balancing
Two-plane dynamic balancing to G2.5 (ISO 21940) standard, G1.0 on request.
Concentricity
Ground magnet OD and journals — ±0.01 mm TIR runout, measured per assembly.
Flux
Helmholtz-coil flux signature per pole — data recorded and shipped with each lot.
Documentation
Flux data, balance records and dimensional reports per the agreed inspection plan.
From Components to Validated Assembly
Component Prep
Magnets, shafts and stacks received or produced; dimensions verified
Assembly
Bonding or overmolding under controlled process parameters
Magnetization
Magnetized in fixture; pole pattern and flux verified
Balancing
Two-plane dynamic balancing to specified grade
Testing
Final flux signature, runout and dimensional release
Validation & Inspection
What we measure before an assembly ships:
- ✓Dimensional — critical dimensions and runout by gauge / CMM per inspection plan
- ✓Magnetic — flux per pole and phase via Helmholtz coil; data recorded and trended
- ✓Dynamic balance — residual imbalance reported against the specified grade
- ✓Project documentation — FAI / PPAP per project requirements
Design Considerations
Send us your drawings — we'll flag these before quoting:
- ✓Magnet retention — surface speed, temperature, and interference fit determine whether adhesive alone suffices or a stainless sleeve is needed
- ✓Skew angle — 1–2 pole skew reduces cogging; costs nothing if specified before production
- ✓Sleeve for high-speed — Inconel or stainless sleeves contain magnet fragments above 100 m/s surface speed — we manufacture these in-house
What We Need to Quote
Provide any of these — the more complete, the faster and more accurate the quote:
- ✓Rotor drawing — magnet dimensions and grade, shaft dimensions, lamination stack details, tolerance callouts
- ✓Performance spec — torque, speed, back-EMF constant, temperature range — we can design the magnet circuit if you prefer
- ✓Volume — prototype quantity and annual volume for tooling amortization
- ✓Testing requirements — flux spec per pole, balancing grade, insulation class, and any OEM-specific standards
Application Gallery
Real applications of Magnetic Rotor Assemblies across industries.
Case Study — EV Drive-Unit Rotor
N38UH segmented rotor with in-house sleeve assembly and dynamic balancing — 180 °C continuous operation.
Frequently Asked Questions
Do you supply the lamination stack too?
Yes — we source or manufacture lamination stacks per your drawing, or accept customer-supplied stacks for assembly. Die-cast aluminum and interlocked stacks are both available.
How do you verify magnetization?
Every rotor passes through a Helmholtz coil fixture that measures flux per pole and phase. We record and trend these values — you receive the data with each shipment. Out-of-spec poles are re-magnetized or rejected.
Can you balance to tighter than G2.5?
We balance to G1.0 for high-speed applications like turbocharger and aerospace components. Below G1.0, material inhomogeneity in the magnets themselves becomes the limiting factor — we can discuss achievable limits for your specific design.
What's the typical lead time?
Prototypes: 2–4 weeks including magnet production. Volume production: 4–8 weeks depending on annual volume and tooling requirements. We hold safety stock for repeating programs.
Have an Assembly Drawing or BOM?
Send it to our team for engineering review and quotation — assembly drawings and BOMs welcome.