In This Article
Key Takeaways
- ◆A single-piece ring removes segment joints but does not guarantee a particular waveform or motor efficiency.
- ◆Segmented construction requires alignment, insulation where specified, bonding and retention checks.
- ◆No universal torque-ripple percentage or volume crossover is established by the available evidence.
- ◆The radial-ring TDS, Rev A of 31 July 2026, states OD 20 to 75 mm, ID 15 to 68 mm, wall 2 to 7 mm and height 5 to 50 mm, with ±0.05 mm standard dimensional tolerance within the qualified route. These limits are not freely combinable. Confirm the drawing, grade, pole pattern and individual features before quotation. The separate integrated-Halbach route states ±0.02 mm on critical features, subject to feature and drawing confirmation.
- ◆Mainrich’s sintered NdFeB range is N30 to N56, with no AH grades. The top grade depends on the temperature series: N56, N54M, N52H, N52SH, N50UH and N45EH. Grades up to N52SH can be made without a Chinese export licence, so we offer those first; UH and EH grades need a licence, applied for per order. Confirm the grade, suffix, geometry and production route for each drawing. This summary does not offer every combination; grades outside it in educational examples are not Mainrich supply offers.
Compare the actual constructions
A radial-oriented ring uses one sintered body. A segmented ring assembles separate magnets around a hub or sleeve. The difference changes orientation tooling, joints, assembly datums and handling. Compare those requirements before committing the drawing.
Material orientation and magnetization
Material orientation established during manufacture constrains the later magnetizing operation. Pole pattern, skew and shape affect the field. A radial label alone does not guarantee a sine wave. Isotropic bonded material follows a different orientation route and must be specified separately.
What the historical comparison measured
The 29 November 2025 external-OD scans compare nominal Ø36.6 × Ø29.8 × 17 mm, 10-pole specimens: radial N45SH, segmented N50SH and integrated Halbach N45SH. Recorded N/S peaks were 415.74/−423.29 mT, 521.39/−519.46 mT and 629.00/−627.71 mT respectively. Probe standoff and measurement uncertainty were not recorded, and the reports give no pass judgement.
These are historical surface-field traces, not air-gap, back-EMF, torque or bore-field measurements. The N50SH specimen is retained as historical evidence, not a current Mainrich offer. The full comparison explains the percentage definitions and measurement limits.
What requires a motor test
Torque ripple, cogging, back-EMF, efficiency and noise depend on the stator, winding, air gap, drive and operating point. Compare complete motors under matched conditions. The available ring scans do not establish a construction-wide advantage or the architecture used by any named robot maker.
Tooling and assembly costs
Compare quotations at the same volume and acceptance standard. Include orientation and magnetizing fixtures, machining, segment assembly, retention, inspection and yield. There is no supported universal 500-pieces-per-month crossover. A segmented option can be evaluated in a robot joint if the complete motor meets its requirements.
Confirm the production route
The radial-ring TDS, Rev A of 31 July 2026, states OD 20 to 75 mm, ID 15 to 68 mm, wall 2 to 7 mm and height 5 to 50 mm, with ±0.05 mm standard dimensional tolerance within the qualified route. These limits are not freely combinable. Confirm the drawing, grade, pole pattern and individual features before quotation.
The separate integrated-Halbach route states ±0.02 mm on critical features, subject to feature and drawing confirmation. Mainrich’s sintered NdFeB range is N30 to N56, with no AH grades. The top grade depends on the temperature series: N56, N54M, N52H, N52SH, N50UH and N45EH. Grades up to N52SH can be made without a Chinese export licence, so we offer those first; UH and EH grades need a licence, applied for per order.
Confirm the grade, suffix, geometry and production route for each drawing. This summary does not offer every combination; grades outside it in educational examples are not Mainrich supply offers.
Frequently Asked Questions
How do the constructions differ?
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A radial-oriented ring uses one sintered body. A segmented ring assembles separate magnets around a hub or sleeve. The difference changes orientation tooling, joints, assembly datums and handling. Compare those requirements before committing the drawing.
How much lower is torque ripple with a single-piece ring?
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Torque ripple, cogging, back-EMF, efficiency and noise depend on the stator, winding, air gap, drive and operating point. Compare complete motors under matched conditions. The available ring scans do not establish a construction-wide advantage or the architecture used by any named robot maker.
At what volume is it cheaper?
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Compare quotations at the same volume and acceptance standard. Include orientation and magnetizing fixtures, machining, segment assembly, retention, inspection and yield. There is no supported universal 500-pieces-per-month crossover. A segmented option can be evaluated in a robot joint if the complete motor meets its requirements.
Can a humanoid joint use segmented magnets?
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Yes, if the qualified motor and retention design meet the requirements. No universal named-OEM architecture is established here.
What grades and tolerances are available?
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The radial-ring TDS, Rev A of 31 July 2026, states OD 20 to 75 mm, ID 15 to 68 mm, wall 2 to 7 mm and height 5 to 50 mm, with ±0.05 mm standard dimensional tolerance within the qualified route. These limits are not freely combinable. Confirm the drawing, grade, pole pattern and individual features before quotation. The separate integrated-Halbach route states ±0.02 mm on critical features, subject to feature and drawing confirmation. Mainrich’s sintered NdFeB range is N30 to N56, with no AH grades. The top grade depends on the temperature series: N56, N54M, N52H, N52SH, N50UH and N45EH. Grades up to N52SH can be made without a Chinese export licence, so we offer those first; UH and EH grades need a licence, applied for per order. Confirm the grade, suffix, geometry and production route for each drawing. This summary does not offer every combination; grades outside it in educational examples are not Mainrich supply offers.
Send the motor drawing and acceptance requirements to compare ring and segmented construction.
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