Humanoid robot joint actuators typically use high-coercivity NdFeB arc segments or radial multipole rings in frameless torque motors, plus low-deviation ring or disc magnets for encoder feedback. A typical platform contains about 28 to 40 motors, so grade, pole geometry, harmonic-drive envelope, and inspection plan must be set for each joint class.
Joint classes need separate decisions for torque, heat, geometry, and feedback.
Radial multipole rings and matched arc segments cover different tooling and assembly paths.
Low-deviation encoder magnets are 100% inspected after magnetization.
Automotive-style evidence is available through the certified CNMAG network partner.
Mainrich reviews the magnetic circuit together with the motor, bearing, encoder, and harmonic-drive interfaces before defining the magnet and inspection plan.
Engineering response within 1 business day. Pricing within 2 business days.
Harmonic-drive integration compresses the motor, bearing, gearbox, and position feedback into one joint envelope. Rotor concentricity, pole placement, adhesive gap, and encoder field angle therefore need one drawing-led review.
| Motor platform | Frameless torque motor |
|---|---|
| Transmission interface | Harmonic / strain-wave drive envelope |
| Rotor path | Radial multipole ring or matched arc set |
| Pole pattern | Drawing-specific count and orientation |
| Encoder target | Diametric ring, disc, or multipole target |
| Sensor deviation | <±3° with 100% inspection |
| Qualification | PPAP Level 3 through the CNMAG route |
Mainrich can deliver individual magnets or a bonded rotor sub-assembly. Review the finished magnet assembly path when adhesive selection, hub fit, magnetization, and balancing need one accountable release plan.
A radial ring and a segmented rotor can meet the same torque target through different manufacturing, magnetization, and assembly routes. Volume and qualification strategy matter as much as the first prototype.
A single ring removes segment gaps and can simplify concentric assembly in compact frameless motors. Pole count, skew, waveform, and post-magnetization inspection are defined against the finished joint geometry.
Precision-ground arc segments support a wide diameter range, prototype iteration, and drawing-specific pole layouts. Matched sets control dimensional and magnetic variation before bonding into the rotor.
Compare the N30 to N58 NdFeB production range, read the broader robotics application brief, or send Mainrich an actuator drawing.
Temperature class follows the hottest credible rotor condition, including continuous load, peak current, limited airflow, and heat conducted from bearings and the gearbox. The class ceiling still needs design margin.
Mechanical inspection, magnetic mapping, encoder-axis control, and PPAP evidence are connected to the same drawing revision and qualification plan.
Bore, OD, thickness, arc profile, concentricity, and mating features are inspected against the agreed drawing and tolerance plan.
Rotor pole output is checked against the control plan. Sensor-grade encoder magnets with deviation below ±3° are 100% inspected after magnetization.
Shenyang General Magnetic supports PPAP Level 3 under its ISO 9001:2015 and IATF 16949:2016 certifications for programs that require an automotive-style qualification path.
Mainrich engineers and quality-controls the program across the four-site production network Mainrich holds equity stakes in.
These are the decisions that most often change grade, geometry, inspection, or assembly scope.
Frameless torque motors commonly use a radial multipole ring or a matched set of arc segments. The choice depends on rotor diameter, pole count, air-gap target, tooling plan, assembly method, and annual volume. Encoder feedback normally uses a separate ring or disc magnet with its own pole-position specification.
No. A single radial multipole ring can improve concentricity and remove segment gaps, while arc segments offer greater tooling flexibility and a practical path across more rotor diameters. Mainrich reviews both architectures against the motor and harmonic-drive tolerance stack before recommending one.
Selection starts with the peak magnet temperature, duty cycle, motor load line, peak-current demagnetizing field, and cooling path. The class rating is a material ceiling, not a target rotor temperature, so the final grade needs working margin under the worst credible joint cycle.
Yes. Sensor-grade ring and disc magnets can be specified with a deviation angle below ±3 degrees and 100% post-magnetization inspection. Pole count, air gap, sensor position, and target field waveform should be included in the drawing review.
Yes. PPAP Level 3 work is routed through Shenyang General Magnetic, also known as CNMAG, the ISO 9001:2015 and IATF 16949:2016 certified partner in the production network Mainrich holds stakes in. Mainrich remains accountable for engineering review, quality control, and release coordination.
Send the motor section, joint duty cycle, encoder target, and annual volume. An engineer responds within 1 business day. Pricing follows within 2 business days.