01 — Overview
About Radial Multi-pole Ring Magnets
Radial multi-pole rings are manufactured as a single piece with curved magnetic orientation between poles, delivering a naturally sinusoidal surface flux distribution and inherent mechanical balance. Unlike segmented arc assemblies, there are no adhesive joints, no flux discontinuities, and no assembly labor.
The architecture is the default choice for humanoid robot joint actuators, collaborative robot motors, high-performance servo drives, and any application where torque smoothness is essential. Typical pole counts are 4, 6, 8, 10, 12, and 14 poles.
02 — Production Capability
What we can hold
- Pole counts: 4, 6, 8, 10, 12, 14+ poles
- OD range: 15mm to 250mm
- ID tolerance: ±0.02mm (servo-grade)
- Concentricity: ≤0.02mm
- Surface flux variance: <1% ring-to-ring
- Sinusoidal waveform output — verified per batch
- Full grade range including GBD-processed SH and UH
03 — Typical Use Cases
Where Radial Multi-pole Ring magnets go to work
Humanoid robot joint actuators (Figure, Optimus, Digit, Apollo, NEO class)
Collaborative robot joint motors
High-performance servo motors
Premium BLDC motors for e-bikes, power tools, and compact EVs
Surgical robot actuators
High-precision linear motors
04 — Dimensions & Tolerances
Typical Dimensions & Tolerances
| Parameter | Specification |
|---|---|
| Typical dimensions | OD 15–250mm, wall thickness 2–10mm, axial length 5–80mm |
| Tolerances | ID ±0.02mm, OD ±0.05mm, concentricity ≤0.02mm, perpendicularity ≤0.03mm |
Tighter spec?
These are typical production ranges. Send your drawing with the critical surfaces called out and we will confirm what we can hold against your tolerance stack-up.
05 — Recommended Grades
Recommended Grades for Radial Multi-pole Ring
N42SH
150°CWorkhorse SH-grade NdFeB for 150°C traction motors, robotics actuators, and high-duty servo drives.
N45SH
150°CHigh-flux SH-grade NdFeB for compact, high-torque motors operating continuously up to 150°C.
N48SH
150°CPremium SH-grade NdFeB, the gold-standard magnet for high-performance EV and robotics motor rotors.
N45UH
180°CTop-tier UH-grade NdFeB, rare production, reserved for the highest-performance traction and extreme-temperature motors.
06 — Related Applications
Related Applications
Robotics
Radial multi-pole rings, joint-motor magnets, and high-torque servo-motor assemblies for humanoid robots, collaborative robots, and industrial robotic systems.
EV Motors
High-performance NdFeB magnets for electric vehicle traction motors, auxiliary drives, and e-axle systems, with the temperature stability and flux density required for continuous high-torque service.
Industrial Automation
NdFeB magnets for stepper motors, servo drives, linear actuators, magnetic couplings, and factory automation equipment across European and North American manufacturing.
Frequently Asked Questions
What is a radial multi-pole ring magnet?
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A radial multi-pole ring is a single-piece sintered NdFeB magnet manufactured with curved magnetic grain orientation that creates alternating north-south poles around its circumference. The curved grain structure produces a naturally sinusoidal surface flux distribution, which results in smooth torque output with minimal cogging when used as a motor rotor. The architecture is the standard for humanoid robotics, collaborative robots, and high-performance servo applications.
How is a radial multi-pole ring different from a segmented arc assembly?
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A segmented arc assembly is built from individual arc-shaped magnets bonded together to form a ring, with adhesive joints between segments creating flux discontinuities and typically higher torque ripple (8–15% vs 2–5% for radial multi-pole). Radial multi-pole rings eliminate the assembly labor and inherent variability of segmented designs at the cost of higher tooling investment. For production volumes above approximately 500 units per month, radial multi-pole rings are typically more cost-effective on a total-landed-cost basis.
What is the minimum order quantity for radial multi-pole ring prototypes?
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Prototype batches of 50 pieces ship in 2–3 weeks. First production lots typically start at 500 pieces with 6–8 week lead time. Ongoing production volumes are flexible from 500 to 50,000+ pieces per month depending on dimensional complexity and grade.
Next step
Request a Quote for Radial Multi-pole Ring Magnets
Share dimensions, quantity, grade, and target application. Our engineering team responds within 1 business day with a grade recommendation, followed by pricing and lead time within 2 business days.