Neodymium Magnets for Humanoid Robots
Every humanoid runs on 28 to 40 little motors — and each one needs the right magnet. We make all of them: segmented arc magnets for the hip, knee, and shoulder joints, micro blocks for fingers and wrists, and precision rings for the encoders. Built to stay strong when a joint runs hot, held to ±0.02mm, and scaled from your first prototype to full production.
Look inside any humanoid robot and you'll find 28 to 40 electric motors packed into a human-shaped body — in the hips, knees, shoulders, wrists, even the fingers. Almost every one runs on a neodymium magnet, and if the magnet is wrong, the joint is wrong. Mainrich has built NdFeB magnets for 30+ years, and for humanoids we make all three kinds you'll need: segmented GBD N45UH–N48UH arc magnets for the high-torque hip, knee, and shoulder motors; micro N52M blocks for finger and wrist drives; and diametrically magnetized rings for the encoders that tell the robot where each joint is. Every one is matched to its job — strong enough to handle peak torque and the heat of a hard-working joint, and precise enough to keep the motion smooth and quiet.
This is the humanoid-focused page in our wider magnets for robotics program. Maybe you're building a brand-new platform and just need a handful of prototypes, or you're qualifying a second supplier for production — either way, send us your motor or sensor drawing (under NDA) and we'll recommend the grade, coating, segmentation, and dimensions, then back it up with demag curves, dimensional reports, and the export paperwork. Everything is made to order, so there's no minimum quantity.
Supply-chain transparency: Heavy rare earth materials (Dy / Tb) are sourced exclusively through MIIT-licensed channels. We prepare the country-of-origin certificates, conflict-mineral declarations, and end-use documentation each shipment needs, and guide you through the export-license application itself. Approval is case-by-case under China's 2025 dual-use export controls — it depends on documentation, product sensitivity, and destination — but with complete, accurate paperwork many clients clear approval in 2–4 weeks. Our quality system is certified to ISO 9001 and IATF 16949.
Pick a magnet that's even slightly too weak, and it will quietly fail you in the field. Under peak-torque current — or just the constant heat of a joint buried inside a leg or torso — an under-spec'd grade starts to lose its magnetism for good. Torque drops, cogging creeps in, and your balance and manipulation control drifts. Our engineers match the grade, knee-point temperature, and segmentation to each joint before you spend anything on tooling, so it doesn't get to that point.
Why Humanoid Joints Are the Hardest Magnet Problem in Robotics
A humanoid has to be strong, light, and quiet at the same time. That forces every joint motor toward maximum torque density — and pushes the permanent magnet to its thermal and coercive limits.
Most humanoid joints use frameless torque motors — a ring of magnets spinning inside a stator, with no housing or bearings of its own — built straight into the actuator. Engineers squeeze these for every bit of torque per kilogram they can get (the target is 30–50 Nm/kg), often using high pole counts and Halbach layouts. To put that in scale: Tesla's Optimus carries 28 of these actuators — 14 rotary and 14 linear — and every one is working near its limit whenever the robot stands, balances, or lifts.
The hard part is heat. Ordinary NdFeB starts to lose its magnetism above about 80–100°C — but a joint that runs all day, with almost no airflow, sails right past that. Adding the heavy rare earths dysprosium and terbium (Dy/Tb) lifts the safe temperature to 180–220°C. That's why these joints need UH-class grades instead of a standard N52 — and why we use Grain Boundary Diffusion to get there without paying for, or depending on, a pile of scarce Dy/Tb.
Magnet-driven actuators in a single humanoid robot
Torque density target for frameless joint motors
Usable temperature once Dy/Tb is added — vs ~100°C for plain NdFeB
Why High-Speed Humanoid Motors Need Segmented Magnets
A frameless torque motor flips its magnetic field thousands of times a second. All that switching stirs up tiny swirling currents — eddy currents — inside the magnet itself. They do no useful work; they just turn into heat and push the magnet toward its knee point. Hit Run motor below to watch the difference between a solid magnet and a segmented (sliced) one.
One large conductive body lets eddy currents circulate freely. Loss and heat build fast — the magnet runs hot and risks irreversible demagnetization.
Thin epoxy-insulated slices break the eddy-current loops into tiny circuits. Rotor magnet loss drops 40–70% and the magnet stays well below its knee point.
Mainrich segmentation capability: block-laminated NdFeB with epoxy insulation layers ≤ 30 μm, typically 4–12 slices per pole, tuned to your inverter switching frequency and rotor geometry. Send your operating frequency and pole layout for a DFM proposal — see our segmented arc magnets and the Grain Boundary Diffusion process behind the coercivity. (The comparison above is a simplified illustration; actual loss reduction depends on your geometry and switching frequency.)
Magnets Matched to Each Humanoid Actuator
A humanoid isn't one magnet specification — it's four. We map grade, shape, and segmentation to the duty of each joint class, from high-torque legs to fingertip drives.
Flagship
Low-Cogging
Micro
Feedback
Diametric Ring — Encoder / Linear
Joint encoder · linear-actuator position feedback
View Sensor Magnets →Why Dy / Tb content matters: heavy rare earths raise coercivity and knee-point temperature, but they also drive price and supply risk. Mainrich applies Grain Boundary Diffusion (GBD) on all SH / UH / EH grades, reducing Dy + Tb usage by up to 70% vs. conventional sintered NdFeB — lower cost, lower exposure to China export-control shocks, identical magnetic performance.
Built for Robot-Grade, Not Commodity
Four capabilities that make Mainrich a qualified humanoid-robot magnet supplier for programs in North America, Europe, and Asia.
Millimeter Tolerance
CNC-ground micro blocks and thin-wall arcs verified on CMM — the precision finger drives and tight joint air-gaps demand.
Segmented & Laminated
4–12 slices per pole with ≤ 30 μm epoxy insulation, cutting eddy-current loss 40–70% in high-speed torque motors.
Grain Boundary Diffusion
Up to 70% less Dy / Tb in UH grades — same Hcj and knee-point, lower cost and supply-chain risk.
Magnets / Month
Dedicated high-temp lines for UH grades. Seamless ramp from joint-actuator prototype to serial fleet supply.
What a Humanoid Magnet Has to Deliver
Six engineering requirements recur across humanoid actuators. Here is how Mainrich meets each.
High Torque Density
With 28–40 actuators in a space- and weight-limited body, every joint motor needs maximum energy product in minimal volume.
BHmax ≥ 45 MGOeThermal Stability 120–150°C
Continuous-duty joints heat-soak with little airflow. The knee point must sit above the worst-case steady-state temperature.
Hcj ≥ 1990 kA/m · UHSegmented / Laminated
High-RPM frameless torque motors suffer eddy-current loss. Segmentation cuts rotor magnet loss and heating substantially.
4–12 slices · ≤30 μm epoxyTight Dimensional Tolerance
Thin-wall arcs and tiny finger-drive blocks run minimal air-gaps. Tolerance controls cogging, torque ripple, and fit.
±0.02mm · CMM verifiedGBD Dy/Tb Traceability
Heavy-rare-earth origin and content are documented per batch, with full export-license application support — essential under tightening export-control regimes.
MIIT-licensed · export supportNo MOQ — Prototype Friendly
Because every order is custom, there is no minimum order quantity. Order the exact prototype count you need, then ramp through pilot to mass production on the same lines.
No minimum orderTrusted by Humanoid Robot Builders
Two representative humanoid programs in pilot or pre-production supply with Mainrich magnets.
Humanoid Robotics Startup — Joint Actuators
Segmented GBD N48UH arc magnets for compact, high-torque-density hip and knee modules. Pilot batches of 500 pcs/quarter scaling toward 10,000 pcs/year by 2027 as the platform moves into serial production.
Humanoid Developer — Full-Body Actuation
Segmented GBD N48UH arc magnets across leg, arm, and waist actuators. Low-cogging segmentation supports smooth dynamic-balance gait control under continuous-duty load.
In a humanoid joint the enemy isn't the peak lift — it's the heat that builds while the robot just stands and balances. We size every joint magnet so the knee point sits well above that steady-state temperature, and we segment the rotor so it doesn't cook itself at speed. That margin is what keeps torque and cogging stable over years of walking.
Robot-Grade Precision, Verified Every Batch
Two capabilities decide whether a magnet is robot-grade or commodity: how tightly it's machined, and how thoroughly it's tested.
Precision CNC Grinding
Thin-wall arcs and micro blocks ground and verified to ±0.02mm for tight air-gaps and dexterous finger drives.
Flux & Dimensional QC
Helmholtz-coil flux testing and dimensional inspection on every batch, with demagnetization curves available per grade.
Vertically Integrated NdFeB Manufacturing
Full production chain in one facility — from raw rare-earth materials to finished, coated, and tested magnets.
Humanoid Magnet Specs & Lead Times
Representative grades, shapes, and dimensions by actuator class. Custom geometries accepted — send your drawing for a quotation within 24 hours. All magnetic values per IEC 60404 test conditions.
| Grade | Shape | Typical Dimensions | Br (kGs) | Max °C | Knee °C | Humanoid Actuator |
|---|---|---|---|---|---|---|
| N48UH | Segmented arc | OD 60 / ID 46 / 30° / W40 mm | 13.9 | 180 | 150 | Hip / knee torque motor |
| N45UH | Thin arc | OD 40 / ID 34 / 60° / W25 mm | 13.5 | 180 | 150 | Shoulder / elbow |
| N52M | Micro block | 6 × 4 × 3 mm (from 3 mm) | 14.4 | 100 | 80 | Finger / wrist drive |
| N45SH | Diametric ring | OD 8 / ID 3 / t3 mm | 13.5 | 150 | 120 | Joint encoder feedback |
| N42EH | Arc / block | Per drawing | 13.0 | 200 | 170 | High-temp / sealed joints |
| Custom | Arc / Block / Ring | Per drawing | — | — | — | Any actuator |
| Order Type | Minimum Order | Lead Time |
|---|---|---|
| Prototype / First Articles | No MOQ — exact count you need | 10–15 business days |
| Pilot / Mass Production | No MOQ — scale on demand | 30–45 business days |
| Monthly Capacity | 5,000,000 pcs (robotics grades) | |
Segmented / laminated magnets available. For high-frequency frameless torque motors where inverter switching drives eddy-current losses, Mainrich supplies block-laminated NdFeB with epoxy insulation layers ≤ 30 μm. Typical segmentation: 4–12 slices per pole, reducing rotor magnet losses by 40–70% versus monolithic blocks. See the Custom Magnet Lead Time Guide for full ordering details.
Coatings & bonding: humanoid rotor magnets are usually bonded into the rotor, so the coating is matched to your adhesive and environment — NiCuNi, single Ni, Zn, black epoxy, or Parylene C (for thin, uniform coverage on micro parts). Magnets ship magnetized or unmagnetized to suit your assembly process. Tell us your bonding adhesive and we'll recommend the coating system.
Every Joint We Supply
From the heaviest leg actuator to the smallest fingertip drive, Mainrich supplies the magnet each humanoid joint class needs.
- Hip & Knee Actuators — high-torque frameless motors; segmented N48UH arc magnets
- Ankle Actuators — compact high-torque joints; segmented UH arc
- Shoulder & Elbow — mid-torque, weight-sensitive; thin N45UH arc
- Wrist Actuators — precise low-mass drives; micro arc / block
- Waist / Torso — continuous-duty balance load; segmented UH arc
- Neck & Head — small, low-cogging positioning motors
- Dexterous Hands & Fingers — N52M micro blocks, ±0.02mm
- Joint Encoders & F/T Sensors — diametric rings for field-angle accuracy
Related Products & Resources
Frequently Asked Questions
Answers to the questions humanoid-robot motor designers and procurement teams ask most.
What magnet grade do humanoid robot joint actuators use?
High-torque hip, knee, and waist actuators use GBD N45UH–N48UH segmented arc magnets — Hcj ≥ 1990 kA/m, knee point ~150°C — because they face both peak-torque demagnetizing fields and continuous heat soak. Finger and wrist micro actuators use high-Br N52M blocks for maximum energy in a tiny package, and joint encoders use diametric N45SH rings. Operating temperature and duty cycle, not just torque, drive the choice. Mainrich engineers confirm the grade against your actuator before tooling.
Can Mainrich supply segmented magnets for high-RPM frameless torque motors?
Yes — segmented (block-laminated) magnets are a core capability for humanoid joints. Frameless torque motors switch their fields at high frequency, inducing eddy currents that heat the magnet and waste power. We laminate the magnet into thin slices with epoxy insulation layers ≤ 30 μm (typically 4–12 slices per pole), which breaks up those eddy-current loops and cuts rotor magnet loss by 40–70%. Send your operating frequency, pole count, and rotor geometry and we'll propose a segmentation pattern.
Can you produce arc magnets with a wall thickness below 3mm?
Yes. Thin-wall arc magnets down to roughly 2–3mm wall are routinely produced for lightweight shoulder, elbow, and wrist actuators, and micro blocks from about 3mm edge length for finger drives. Thin sections require careful grinding and handling to control chipping and tolerance, which is why every piece is CNC-ground and CMM-verified to ±0.02mm. Send your minimum wall and tolerance and we'll confirm feasibility on your specific geometry.
Do you support Halbach-array magnet layouts for higher torque density?
Yes. Halbach arrangements concentrate flux on one side of the rotor to raise torque density — a common technique in high-performance humanoid torque motors. We supply the individually magnetized arc or block segments your motor designer's Halbach layout requires, holding tight magnetization-axis and dimensional tolerances so the assembled array produces the intended one-sided field. Share your segment magnetization directions and geometry and we'll quote the set.
What torque density can these magnets help achieve?
Torque density is a system result — it depends on motor topology, pole/slot count, winding, and cooling, not the magnet alone. That said, modern frameless humanoid joint motors target roughly 30–50 Nm/kg, and getting there requires high energy product (BHmax ≥ 45 MGOe) combined with enough coercivity to hold up at operating temperature. Our role is to supply the highest usable BHmax for your thermal envelope — high-Br UH grades with GBD — and the segmentation that keeps losses low at speed.
Is there a minimum order quantity (MOQ) for humanoid robot magnets?
No. Because every humanoid magnet we make is custom, there is no fixed minimum order quantity — you can order the exact prototype count your build needs, even a handful of first-article pieces. Sample lead time is 10–15 business days. We recommend validating dimensions, magnetization, and thermal behavior on prototypes before scaling, then ramping through pilot to mass production on the same lines. Monthly capacity exceeds 5 million pieces, so there is no ceiling either.
What coatings do you offer for bonded humanoid rotor magnets?
Humanoid rotor magnets are usually bonded into the rotor, so coating choice balances corrosion protection against adhesive compatibility. We supply NiCuNi (triple nickel), single Ni, Zn, black epoxy, and Parylene C — matched to your bonding adhesive and operating environment (epoxy or roughened Ni for structural bonding; Parylene for thin, uniform coverage on micro parts). Magnets can ship magnetized or unmagnetized to suit your assembly line. Tell us your adhesive and environment and we'll recommend the coating system.
What is the lead time from prototype to mass production for robot magnets?
Prototype samples ship in 10–15 business days; pilot and mass-production orders run 30–45 business days depending on grade, geometry, and volume. Because prototype and serial parts are made on the same dedicated high-temp lines, the transition from a validated prototype to qualified serial supply is direct — no re-tooling surprises. Monthly capacity for robotics grades exceeds 5 million pieces, so scaling from pilot to fleet volume is straightforward.
How does Mainrich ensure Dy/Tb traceability under China's rare-earth export controls?
Mainrich operates under MIIT-licensed supply agreements for Dy and Tb and has handled compliant exports since the 2025 dual-use control framework came into force. For every order we prepare the country-of-origin certificates, conflict-mineral declarations, and end-use documentation required, and support you through the export-license application. Approval timelines are case-by-case — they depend on documentation completeness, product sensitivity, and your country and trade history — but with complete, accurate paperwork many clients obtain approval in 2–4 weeks. See our guide to China's 2025 dual-use export controls for what determines timelines. Our Grain Boundary Diffusion process also reduces heavy-rare-earth intensity in UH grades, lowering exposure to future control shocks, and for programs sensitive to supply risk we can stage safety stock against a signed 12-month forecast. For EU chemical compliance, see ECHA REACH guidance.