634 ZZ Deep Groove Ball Bearing for General Compact Machinery | 4x16x5 mm
The 634-ZZ is a Premium Miniature Deep Groove Ball Bearing engineered for applications that demand compactness and reliable performance. Featuring double metal shields (ZZ) on both sides, this precision metric bearing provides effective protection against dust and contaminants while ensuring low-friction operation. With a 4mm bore and a robust outer diameter, it is an ideal choice for small yet demanding applications such as precision instruments, high-performance micro-motors, and compact machinery where space is limited but durability is required.
634 ZZ Deep Groove Ball Bearing 4x16x5 mm | ISO 63 Series – Medium | Double Shielded
A precision miniature bearing built with the universal deep groove geometry. Engineered for smooth and reliable performance at speeds up to 28,000 r/min (Oil). The 634-ZZ ball bearing is capable of supporting significant radial loads relative to its size, making it a versatile and dependable component for industrial, precision mechanical, and high-performance hobbyist equipment.

Ideally suited for a broad spectrum of equipment:
The dual non-contact pressed steel shields offer reliable two-sided protection against dust and larger particles. This effective sealing solution helps retain grease, extend service intervals, and maintain low rotational torque in various operating conditions.
As part of the medium series, the 634-ZZ provides an excellent balance of load capacity, speed capability, and durability within its compact dimensions. Its robust construction is suited for continuous operation in demanding environments.
Manufactured to standard industrial tolerances for reliable quality (up to P5 precision grades). ). Its optimized internal geometry promotes smooth and stable rotation, reducing vibration and noise in applications such as small gear reducers, encoders, and precision mechanisms.
| Bearing Type | Single Row Deep Groove Ball Bearing |
| ISO Dimension Series | 63 Series – Medium |
| Basic Designation | 634 |
| Suffix | ZZ (Both sides with steel shields) |
| Bore Diameter (d) | 4 mm |
| Outer Diameter (D) | 16 mm |
| Width (B) | 5 mm |
| Material (Races & Balls) | Chrome Steel (GCr15 / SAE 52100) |
| Precision Class | Standard / P5 Grade Available |
| Cage Material | Pressed Steel Ribbon |
| Dynamic Load Rating (Cʳ) | 2.52 kN |
| Static Load Rating (C₀ʳ) | 1.12 kN |
| Limiting Speed (Grease) | 22,000 r/min |
| Limiting Speed (Oil) | 28,000 r/min |
| Weight (approx.) | 3.7 g |
Direct replacement for:
The 634-ZZ is supplied with double pressed steel shields as the standard configuration. For environments requiring protection against moisture or where lower starting torque is essential, alternative versions with contact rubber seals (634-2RS) can be selected.
"For applications like small gear reducers, precision motor encoders, or high-torque micro mechanisms, the 634-ZZ provides dependable performance and contamination protection.
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Details
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Details
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Details
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Details
The 6303-ZZ is a Double Metal Shielded Deep Groove Ball Bearing engineered for applications demanding reliable protection against dust and solid contaminants while maintaining high-speed capability. Equipped with two non-contact metal shields (ZZ) on both sides, this bearing effectively prevents ingress of larger particles and retains grease lubrication with minimal friction. With a 17 mm bore, it is a versatile choice for electric motors, pumps, compressors, and industrial equipment where compact dimensions, moderate load capacity, and long service life are required.
Details
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Details
The 6305-ZZ is a Premium Single Row Deep Groove Ball Bearing designed for demanding applications that require reliable performance and durability. Featuring double metal shields (ZZ) on both sides, this metric bearing provides effective protection against dust and contamination while maintaining low rotational friction. With a 25mm bore, 62mm outer diameter, and 17mm width, it is ideal for electric motors, pumps, gearboxes, conveyors, and various machinery where robust construction and long service life are essential.
Details
The 6308 is a Premium Single Row Deep Groove Ball Bearing engineered for medium-to-heavy duty applications requiring reliable performance and extended service life. This metric bearing features an open design, allowing for flexible lubrication options and easy integration into various housing configurations. With a 40mm bore, 90mm outer diameter, and 23mm width, it is ideal for electric motors, pumps, gearboxes, industrial fans, and automotive components where robust construction and high load capacity are essential.
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