01 / Overview
Application Overview
Robot joint motors have different torque, speed and thermal duties. A compact actuator may use segments, a radially oriented ring or another magnet arrangement. A named robot platform does not establish its magnet construction or bill of materials without a model-specific record.
02 / Material
Why NdFeB for Robotics
NdFeB is a candidate when the actuator needs high magnetic output within a small package. Assess the hot working point and complete motor response before selecting the grade or construction.
03 / Specifications
Key Design Requirements
Torque smoothness
Specify cogging and loaded torque-ripple tests for the actual stator, rotor and controller. A surface scan cannot establish either result.
Temperature stability
Measure or model the magnet’s temperature through the joint duty cycle and check hot curves against opposing fields.
Dimensional precision
Derive tolerances from the rotor stack-up. The documented radial-ring window has a standard ±0.05 mm tolerance; tighter features need review.
Production consistency
Agree field measurement location, fixture, sampling and acceptance limits for the selected construction.
Coating durability
Qualify the full coating and retention system for humidity, wear and any cleaning or sterilization exposure.
04 / Grade Selection
NdFeB grade references for Robotics
These educational references do not establish supply or thermal suitability. Review the actual hot curves, load line, opposing field and duty cycle before selecting a grade.
N42SH
150°C class · Super High Temperature (SH)N42SH reference: 40–43 MGOe at 20°C, with a nominal 150°C temperature class.
Reference; drawing review required
N45SH
150°C class · Super High Temperature (SH)N45SH reference: 43–46 MGOe at 20°C, with a nominal 150°C temperature class.
Reference; drawing review required
N48SH
150°C class · Super High Temperature (SH)N48SH reference: 45–48 MGOe at 20°C, with a nominal 150°C temperature class.
Reference; drawing review required
N45UH
180°C class · Ultra High Temperature (UH)N45UH reference: 43–46 MGOe at 20°C, with a nominal 180°C temperature class.
Reference; drawing review required
05 / Geometry
Typical Magnet Configurations
- Radially oriented multipole rings
- Segments assembled around a rotor
- Skewed magnet arrangements
- Laminated magnet assemblies with verified electrical insulation
Typical dimensions
The radial-ring reference documents OD 20 to 75 mm, ID 15 to 68 mm, wall 2 to 7 mm and height 5 to 50 mm. These endpoints are qualification guidance, not every possible combination.
06 / Engineering Notes
Design & Procurement Considerations
- 01The documented 10-pole N45SH radial specimen has a trapezoidal OD surface trace. The separate integrated Halbach specimen has a sinusoidal trace. Neither is a motor efficiency test.
- 02Compare retention, magnet positioning and waveform in the complete actuator before choosing rings or segments.
- 03Set dimensional inspection and field mapping requirements from the failure modes and customer acceptance plan.
- 04Medical and surgical devices need finished-device evaluation; a coating name does not establish biological or MR safety.
07 / Resources
Further Reading
Industry Insight
NdFeB for US Humanoid Robotics: Qualification Before Production Volume
Use the actuator drawing and duty cycle to qualify supply. Public robot production targets do not establish a magnet bill of materials.
Technical
Magnet Requirements for Humanoid Robot Actuators
Specify the motor-side duty, magnetic circuit, material and assembly requirements before qualifying an actuator magnet.
Industry Insight
Magnets for Collaborative Robots (Cobots): Requirements, Grades, and Supplier Selection
Match the magnet specification to the cobot joint’s torque, control, thermal and assembly requirements.
Buyer's Guide
How to Choose a Neodymium Magnet Supplier for Robotics and Servo Motors
Compare suppliers using the actual actuator requirements, sample evidence and production responsibilities.
08 / Compare
Related Engineering Comparisons
Comparison
Radial Multi-pole vs Arc Segment
A radial ring has one magnetic body; a segmented rotor uses separate magnets. Compare the waveform and assembly in the actual motor.
Comparison
N45SH vs N48SH
Compare N45SH and N48SH at 20°C, then assess the actual material at the intended operating point.
Comparison
N42 vs N42SH
Compare N42 and N42SH at 20°C, then assess the actual material at the intended operating point.
FAQ / Questions
Frequently Asked Questions
What type of magnet is used in robot joint motors?
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Possible constructions include segments and one-piece oriented rings. Selection depends on the motor geometry, waveform, retention and manufacturing plan. The documented radial sample is trapezoidal at the OD probe; a sinusoidal field is not a general property of radial rings.
What temperature class do robotics motor magnets need?
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Use the magnet temperature through the worst duty cycle, including hot spots and faults, with the load line and opposing fields. The nominal H, SH and UH classes are reference labels. They do not provide a guaranteed safety margin.
How tight should robot motor magnet tolerances be?
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Derive the tolerances from the complete rotor assembly and measurement plan. Within its documented size window, the radial-ring reference states ±0.05 mm standard dimensional tolerance. Tighter features require drawing review. The separate integrated Halbach net-shape claim must not be applied to radial rings.
Start an RFQ
Request a Quote for Robotics
Share your application, target dimensions, operating temperature, and annual volume. We respond within 1 business day. Grade, production route and inspection requirements are confirmed before a part-specific supply promise.