Magnet Requirements for Humanoid Robot Actuators

State the rotor envelope, stator geometry, air gap, pole count, winding and drive. These determine the field requirement and the operating point. An energy-product number by itself cannot determine the torque constant or efficiency.

Select the grade using the actual hot demagnetization curves, the magnetic circuit working point and the worst opposing field. A suffix is a nominal material class, not a guaranteed motor temperature limit or a chemical recipe. 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.

The reported N45H magnetic comparison and the separate historical 50H Dy-reduction example have different scopes. See the GBD evidence and limitations. Finished-part savings require a quotation and qualification of the proposed route.

Compare one-piece radial rings and segmented assemblies against electromagnetic, thermal, structural and cost requirements. The OD scan comparison records historical specimens; it does not establish motor torque or a universal construction choice.

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. Specify coated dimensions, assembly datums, bond line and retention. Assess the complete hot rotor and overspeed condition; a loose-magnet tolerance does not establish shaft concentricity or balance.

Distinguish bulk material properties, magnetic moment, OD scan, air-gap field and motor back-EMF. State measurement conditions and acceptance limits for the quantities the design needs. Agree qualification and production sampling, with traceability to the manufacturing route.

Check the current certificate for the actual manufacturing entity, address and activity. Agree PPAP level and required reports for the order; a network relationship does not certify every plant or assembly. Agree tooling, sample quantity, inspection and production milestones in the quotation. Export release depends on any required authorization.

No standard prototype quantity or fixed delivery interval is promised here. Grade suffixes and F/N/D series labels do not establish composition or export clearance. Classify the actual item and transaction with the exporter, including the parties, end use and route. See the export-control guide.