684, 684Z, 684ZZ, 684RS, 684-2RS Ball Bearings 4x9x4mm – Ultra-Miniature Deep Groove Ball Bearings for High-Speed & Precision Micro Mechanical Systems

684, 684Z, 684ZZ, 684RS, 684-2RS Ball Bearings 4x9x4mm – Ultra-Miniature Deep Groove Ball Bearings for High-Speed & Precision Micro Mechanical Systems

Ultra-compact 684 series deep groove ball bearings in size 4mm (ID) × 9mm (OD) × 4mm (W), designed for micro-mechanical applications where space is limited and smooth, high-speed rotation is essential. Available in multiple sealing configurations to suit diverse operating conditions:

• 684: Open type – ideal for clean environments or custom lubrication
• 684Z / 684ZZ (684-2Z): Single or double metal shields – protect against fine dust while retaining lubricant
• 684RS / 684-2RS: Single or double rubber seals – offer superior resistance to moisture, dirt, and contaminants

Manufactured from high-quality chrome steel (GCr15), these micro bearings feature precision-ground raceways for low-noise, low-friction performance under light radial loads. Commonly used in miniature motors, dental and surgical tools, micro drones, smart watches, robotics joints, tiny cooling fans, lab automation, and precision instrumentation.

Most sealed models are pre-lubricated with high-performance grease for maintenance-free operation. The 684 series supports both radial and limited axial loads, making it ideal for ultra-compact, high-RPM systems requiring reliability, quietness, and long service life.

🔧 Key Specifications:

• Models: 684, 684Z, 684ZZ (684-2Z), 684RS, 684-2RS
• Dimensions: 4 × 9 × 4 mm
• Material: Chrome Steel (GCr15)
• Precision Rating: ABEC-1 (ISO P0)
• Ideal for: Micro motors, medical devices, wearables, and precision micro-mechanisms