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684 / 684ZZ / 684-2RS Ultra-Miniature Ball Bearing (4mm x 9mm x 2.5mm / 4mm)
- Delivers high torque density in a compact diameter design
- Precision gear structure ensures smooth & ultra-low noise operation
- Wide output speed range to meet versatile industrial needs
- Fully customizable gear ratios, shaft dimensions, and wire leads
- Heavy-duty industrial grade quality with long operational lifespan
Key Features
Engineered for superior reliability, high torque efficiency, and low-noise continuous operations.
Ultra
miniature metric dimensions (4mm ID x 9mm OD) suited for compact mechanical assemblies
Available in open type (2.5mm width) and shielded / sealed type (4mm width)
High
carbon chromium bearing steel (GCr15) providing superior surface hardness and fatigue resistance
Capable of high rotational speeds up to 63,000 RPM under oil lubrication
Precision ground raceways ensuring sub
micron concentricity, low vibration, and quiet rotation
Ultra
low starting torque optimizing energy efficiency for battery-powered micro drives
ABEC
3 / ABEC-5 precision rating guaranteeing reliable rotational accuracy under load
Full RoHS and REACH environmental compliance across all manufacturing processes
Technical Specifications
Detailed engineering parameters, mechanical dimensions, and electrical performance figures.
| Parameters | Specifications |
|---|---|
| Inner Diameter | 4mm |
| Outer Diameter | 9mm |
| Width | 4mm |
| Precision Rating | P0 |
| Clearance | C0 |
| Sealing Type | ZZ |
| Number of Row | Single Row |
| Material | chrome steel |
| Grease RPM Limit | 2000 RPM |
| Lubrication | Grease |
| Size | 4*9*4MM |
| Certificate | ISO9001 |
| Weight | 0.01(kg) |
Why Choose Us
Direct industrial manufacturing capabilities, certified international quality standards, and dependable engineering support.
Factory Manufacturing Capabilities
Modern precision workshop, advanced CNC automated machining centers, and 100% full-inspection assembly lines.
CNC Machining Workshop
High precision ±0.005mm tolerance
Automated Assembly Lines
Capacity up to 50,000 units/month
Rigorous QC & Testing Lab
Noise, torque & life cycle testingInternational Certifications
Verified compliance with global standards, supporting smooth customs clearance and regulatory approvals across North America and Europe.
ISO9001
European Conformity Verified
CE RoHS
Eco-friendly & hazardous-free
CE
Standardized Quality Management
