Cases

How to Select Bearings for Robots

A cross roller bearing is a high-precision component where cylindrical rollers are arranged in an alternating, 90-degree crisscross pattern within a single raceway. This unique design allows a single bearing to simultaneously handle radial, axial, and moment (tilting) loads, often replacing the need for multiple standard bearings.

Core Selection Principles

Crossed Roller Bearings (First Choice for Rotary Main Joints)

Structural Features: Rollers arranged at 90° cross arrangement, single bearing handles radial + axial + overturning moment, zero backlash, ultra-high rigidity.

Typical Series: RU, CRBH, RB, RA, SXU .

Application Scenarios: Humanoid robot shoulders, elbows, hips, waist main joints; industrial arm upper arm/lower arm joints; precision rotary tables .

2026 Domestic Parameters: Precision up to P4 grade, some companies breakthrough P2; ultra-thin type wall thickness 5mm, axial clearance 0.002–0.005mm .

Selection Key Points: Choose model based on overturning moment,priority pre-tightening adjustable structure; heavy-load joints select high roller count design.

Harmonic Drive Flexible Bearings (The "Heart" of Transmission Core)

Structural Features: Extremely thin outer ring,adaptation wave generator and flexspline high-frequency elastic deformation,bear cyclic alternating stress.

Core Requirements: Material fatigue strength, dimensional accuracy, deformation consistency extremely high, decisive component for reducer life.

Application Scenarios: Core component of harmonic reducers, all rotating joint transmission chain in humanoid robots.

2026 Domestic Parameters: Standard life ≥12,000h, some companies reach 30,000h; deformation consistency error ≤0.003mm.

Selection Key Points: Match size with flexspline/wave generator;priority high fatigue strength bearing steel + special heat treatment solutions.

Angular Contact Ball Bearings

Structural Features: Can bear radial + axial combined loads,paired installation with pre-tightening to eliminate clearance, high speed, high rigidity.

Application Scenarios: Joint motor spindles, knee/elbow high-speed oscillating positions; linear joint screw support ends .

2026 Domestic Parameters: P4 grade precision,after installation in pairs radia lbeat ≤0.001mm; dn value ≥1.5×10⁶.

Selection Key Points: Choose contact angle based on load direction (15°/25°/40°); high-speed scenarios select ceramic hybrid balls to reduce friction .

Four-Point Contact Ball Bearings

Structural Features: Single row bear bidirectional axial loads, reduces bearing count, saves installation space.

Application Scenarios: Humanoid robot linear joints (e.g., knee screw); collaborative robot rotary mechanisms; reducer output item .

2026 Domestic Parameters: Constant section design, axial rigidity 30% higher than traditional structures; zero backlash after preload.

Selection Key Points: Compact space priority constant section series; bidirectional axial load scenarios alternative double-row angular contact.

Deep Groove Ball Bearings

Structural Features: Low friction resistance, high speed, low cost, easy installation and maintenance.

Application Scenarios: Robot end effectors, light joints, sensor brackets; low-load, low-rigidity requirement positions .

Selection Key Points: Prioritize thin-wall type; high-precision scenarios select P5 grade,ordinary scene select P0 grade.

Self-Lubricating Spherical Plain Bearings

Structural Features: Spherical sliding structure + PTFE composite liner, supports large-angle deflection.

Application Scenarios: Humanoid robot ankles, hand joints; outdoor robots, collaborative robots in harsh conditions.

2026 Domestic Parameters: Operating temperature -30°C to 120°C, friction coefficient ≤0.08, maintenance-free cycle ≥5,000h .

Selection Key Points: Suited for multi-directional motion needs;joint area with linkage structure used together .

Humanoid Robot Complete Bearing Selection List (2026 Mass Production Reference)

Taking a single humanoid robot (70+ bearing configuration) as an example, the selection of core parts is as follows :

Core Breakthrough Points

Precision: Domestic crossed roller bearing precision reaches 0.005mm, approaching international levels; some companies achieve P2 grade small-batch supply.

Materials: High-performance bearing steel + nano-coatings, enhancing wear and corrosion resistance; ceramic hybrid ball bearings gradually scalable application .

Process: Laser precision machining, intelligent heat treatment universal, bearing life improved by 20%–30%.

Practical Selection Recommendations

Scenario-Based Prioritization: Main joints prioritize crossed roller bearings, transmission chains prioritize flexible bearings, high-speed parts prioritize angular contact ball bearings .

Localization Substitution: Medium-low load joints can use domestic P4 grade crossed roller bearings; harmonic drive flexible bearings it is recommended to verify first domestic leading companies' products.

Preload & Clearance: All precision joint bearings must apply preload to eliminate backlash; adjust preload force based on load magnitude,avoid over-preload causing heat generation .

Customization Needs: Special joints in humanoid robots can adopt constant section thin-wall design + built-in torque measurement function to improve control accuracy .

For technical specifications, pricing, or custom engineering solutions:

Email: frank@newbeetrans.com

Website: www.newbeetrans.com