Magnets for Collaborative Robots (Cobots): Requirements, Grades, and Supplier Selection

Collaborative robots (cobots) operate alongside humans without safety cages. This imposes unique requirements on every component, including the magnets in their joint motors. Cobots must be precise, backdrivable (a human can push the arm and the motor doesn't resist), and smooth in their motion. Any torque ripple or cogging translates directly into reduced positioning accuracy and a less comfortable interaction for human workers. The global cobot market is projected to reach $12.3 billion by 2030 (MarketsandMarkets), driven by manufacturing, logistics, and healthcare applications.

A typical 6-axis cobot contains 6 joint actuators, each with a PMSM or BLDC motor and a harmonic drive or cycloidal reducer. The motor magnets must deliver high torque density in a compact form factor while maintaining smooth rotation at very low speeds (for precision positioning) and very high speeds (for rapid movement between positions).

• •Torque density: Higher is better - compact joints are a competitive advantage
• •Torque smoothness: <3% torque ripple for precision applications
• •Backdrivability: The motor must not resist external force - smooth magnets help
• •Thermal stability: Joint motors heat up during sustained loads; magnets must not demagnetize
• •Consistency: Hundreds or thousands of identical motors need identical magnet performance

Based on our work with cobot manufacturers, here are the typical magnet specifications for joint motors in collaborative robots:

• •Grade: N48SH or N50H - balances flux density with thermal stability up to 120–150°C
• •Architecture: Radial multi-pole ring (preferred) or precision segmented arc assembly
• •Pole count: 8–14 poles is common for cobot joint motors
• •ID tolerance: ±0.02mm (critical for air gap consistency)
• •Flux variance: <1% ring-to-ring (essential for consistent motor performance across units)
• •Coating: NiCuNi standard; epoxy for harsh environment cobots

Cobot manufacturers face a unique supply chain challenge: they need the precision of aerospace-grade magnets at the cost structure of industrial-grade components. Most magnet suppliers are optimized for one or the other - high-precision/high-cost or commodity/low-cost. Finding a supplier that can deliver ±0.02mm tolerances, <1% flux variance, and competitive pricing requires a manufacturer with advanced grinding equipment, in-house GBD processing (to reduce rare earth costs), and 100% testing infrastructure.

We work with cobot and industrial robot companies across Asia, Europe, and North America. Our robotics magnet line was specifically designed for joint motor applications.

• •Radial multi-pole rings in 4–14 pole configurations
• •GBD-processed N48SH and N50UH at near-standard pricing
• •100% flux mapping with data reports shipped with every batch
• •Prototype batches (50+ pieces) in 2–3 weeks
• •Dedicated English-speaking engineering support for motor design consultation
• •Export compliance handling for all grades including controlled materials