High-Precision Brushless Motor Rotor Magnet

Name: High-Precision Brushless Motor Rotor Magnet
Brand: YXMAGNET

Why the magnet decides torque ripple

A brushless motor's torque ripple, cogging and efficiency are decided at the magnet, not at the controller. This page is for engineers specifying rotor magnets for brushless DC motors, PMDC motors, e-bike hub motors and robot-vacuum traction motors. We produce the arc and tile segments, the Halbach layouts and the assembled rotor sub-systems that go into them.

Grade first, then flux

Rotor magnets run hot, and grade selection should start from the operating temperature rather than from the highest available flux. The temperature ladder is: N series up to 80 °C, M up to 100 °C, H up to 120 °C, SH up to 150 °C, UH up to 180 °C and EH up to 200 °C. For a rotor that will soak in a hot housing, an SH or UH grade is usually the right answer; the trade-off is a small loss of flux against the room-temperature grades.

Geometry: arc segments and Halbach arrays

We make arc and tile segments to drawing for radial rotors, curved arc OEM geometries, and multi-segment Halbach arrays where the magnetization pattern rotates by a fixed angle from segment to segment instead of pointing straight at the axis. Magnetization direction is not limited to a single pole: radial, axial, diametral and custom multi-pole patterns are all available, and we build dedicated magnetization fixtures for rotor work so the pattern is reproduced part to part.

Tolerance and assembly

Standard dimensional tolerance is ±0.05 mm, which is what a rotor stack normally needs so that segments seat without rocking; where a drawing calls for tighter control, critical dimensions are held to ±0.02 mm using grinding or wire-cutting. Because we also build the steel housing and the rotor sub-assembly, the magnet and the stack tolerance are controlled by the same process rather than negotiated between two suppliers.

Coating

Ni-Cu-Ni is the usual choice for a rotor that will be handled during assembly and see condensation; epoxy is used where a motor is expected to see humidity or a wash-down environment. Salt-spray duration is matched to the coating across a 12–96 hour window rather than fixed at one number.

Lead time and samples

Samples run 10–15 days, small batches 20–30 days and mass production 40–60 days. In-stock samples are free of charge — you pay only the freight. Send the rotor OD/ID, the segment count, the operating temperature and the required flux, and we confirm feasibility within one business day.

Available magnetisation directions — Ring magnets

The magnetisation direction is fixed when the magnet is magnetised and cannot be changed afterwards, so the direction must be confirmed before production.

Axially MagnetizedPoles are on the two flat end faces of the ring.
Diametrically MagnetizedPoles are split across the ring — one half is N, the other half S.
Multi Axially MagnetizedAlternating N and S poles around the circumference — pole count to your drawing.

Manufacturing capability & measured data

Tolerance

Standard production: ±0.05 mm
Critical dimensions (on request): ±0.02 mm

Quoted per dimension against international dimensional quality standards, not as one blanket percentage. ±0.05 mm is the standard band; where a drawing calls for more, critical dimensions are held to ±0.02 mm using grinding or wire-cutting. The final tolerance is confirmed against your drawing before production.

Salt spray

Duration depends on coating: 12 – 96 h

Tell us how many hours your application needs and we match the coating to it. The test standard and the hours each coating reaches are confirmed on request.

Lead time

Sample: 10 – 15 days
Small batch: 20 – 30 days
Mass production: 40 – 60 days

Bands are by order type, not a single quantity threshold; exact lead time is confirmed at quotation.

Catalogue range and specialty grades

Standard catalogue range: N35–N52 (M–AH series)
Specialty grade, on request: N54 / N55
Designation: N54 (China) · N55 (international)