Products
MR Series Deep Groove Ball Bearings
Product Overview
The MR Series Deep Groove Ball Bearings belongs to the “miniature bearing series” within the deep groove ball bearing family, representing one of the smallest deep groove ball bearing categories available on the market. Bore sizes typically range from 2 mm to 15 mm, making this series purpose-built for precision small-scale applications with extremely demanding installation space requirements. Unlike series such as the 62, 63, 68, and 69, which follow the ISO 15 standard series designation system, the MR Series uses an industry-common bore-to-outer-diameter numbering convention. It is recommended to verify selections based on specific dimensional parameters (bore × outer diameter × width) rather than relying solely on the model designation.
In terms of materials, the MR Series is commonly manufactured from stainless steel (e.g., 440C), offering good corrosion resistance suitable for moisture-prone environments and medical applications with high cleanliness and anti-rust requirements. Sealing options include open type, single and double-sided metal shields (Z/ZZ), and rubber contact seals (RS/2RS), allowing flexible selection based on the dust protection, lubricant retention, and friction loss requirements of precision miniature equipment.
Technical Specifications
| Bearing No. | d (mm/in) | D (mm/in) | Open B (mm/in) | Sealed B (mm/in) | Chamfer (mm/in) | Cr (N) | C0r (N) | Weight (kg) |
|---|---|---|---|---|---|---|---|---|
| MR84 | 4 / 0.1575 | 8 / 0.3150 | 2 / 0.0787 | 3 / 0.1181 | 0.10 / 0.004 | 181 | 78 | 0.00056 |
| MR85 | 5 / 0.1969 | 8 / 0.3150 | 2 / 0.0787 | 2.5 / 0.0984 | 0.08 / 0.003 | 181 | 78 | 0.00025 |
| MR95 | 5 / 0.1969 | 9 / 0.3543 | 2.5 / 0.0984 | 3 / 0.1181 | 0.15 / 0.006 | 332 | 142 | 0.00058 |
| MR104 | 4 / 0.1575 | 10 / 0.3937 | 3 / 0.1181 | 4 / 0.1575 | 0.15 / 0.006 | 715 | 265 | 0.00133 |
| MR105 | 5 / 0.1969 | 10 / 0.3937 | 3 / 0.1181 | 4 / 0.1575 | 0.15 / 0.006 | 460 | 196 | 0.00126 |
| MR106 | 6 / 0.2362 | 10 / 0.3937 | 2.5 / 0.0984 | 3 / 0.1181 | 0.10 / 0.004 | 460 | 196 | 0.00070 |
| MR115 | 5 / 0.1969 | 11 / 0.4331 | 4 / 0.1575 | 4 / 0.1575 | 0.15 / 0.006 | 735 | 284 | 0.00062 |
| MR117 | 7 / 0.2756 | 11 / 0.4331 | 2.5 / 0.0984 | 3 / 0.1181 | 0.10 / 0.004 | 450 | 206 | 0.00071 |
| MR126 | 6 / 0.2362 | 12 / 0.4724 | 3 / 0.1181 | 4 / 0.1575 | 0.15 / 0.006 | 774 | 329 | 0.00166 |
| MR128 | 8 / 0.3150 | 12 / 0.4724 | 2.5 / 0.0984 | 3.5 / 0.1378 | 0.10 / 0.004 | 510 | 255 | 0.00090 |
| MR137 | 7 / 0.2756 | 13 / 0.5118 | 3 / 0.1181 | 4 / 0.1575 | 0.15 / 0.006 | 715 | 265 | 0.00201 |
| MR148 | 8 / 0.3150 | 14 / 0.5512 | 3.5 / 0.1378 | 4 / 0.1575 | 0.15 / 0.006 | 715 | 265 | 0.00219 |
| MR166 | 6 / 0.2362 | 16 / 0.6299 | 6 / 0.2362 | 6 / 0.2362 | 0.15 / 0.006 | 1470 | 600 | 0.00580 |
Key features
- Ultra-small bore size range — covering 2-15 mm, meeting rotational support needs under extreme space constraints
- High-precision rotational performance — suitable for precision mechanisms requiring smooth operation and low noise
- Corrosion-resistant material options — stainless steel construction extends service life in moisture-prone and medical environments
- Lightweight construction — aligns with the miniaturization trend toward low-weight, low-inertia components
- Multiple sealing options available — balances dust/moisture protection with low friction loss across different operating conditions
Applications
In precision instruments and measuring devices, the MR Series is widely used in watch movements, sensors, and other precision mechanisms requiring micron-level rotational accuracy.
In medical devices, the series is commonly applied in dental handpieces, micro-pumps, and other medical equipment components with stringent size and cleanliness requirements.
In model and hobby equipment, the MR Series is a common choice for drone motors, RC model vehicles/boats, and other miniature drive systems, supporting stable operation of small power systems through its lightweight design and high-speed performance.
In optical and precision mechanical equipment, including camera micro-mechanisms, scanning devices, and other optoelectronic integrated equipment, the series provides compact yet reliable rotational support.
The MR Series is also commonly found in small electronic products, precision gearboxes, and miniature transmission components — applications where strict size limitations apply while stable rotational performance remains essential.
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Technical Resources
Whether you are an engineer, procurement manager, or equipment maintenance professional, here you will find in-depth content covering bearing operating principles, technical parameter interpretation, industry application analysis, and selection logic — helping you build a comprehensive understanding of bearing products and make more informed decisions in real-world applications.
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FAQs
What loads can deep groove ball bearings handle?
Deep groove ball bearings are primarily designed for radial loads, but they can also handle moderate axial (thrust) loads in both directions. They are not suitable for heavy axial loads or combined shock loads. In those cases, angular contact or tapered roller bearings are preferred.
How do I select the right bearing size for my application?
Selection should be based on bore diameter (shaft size), required load capacity (dynamic rating C and static rating C0), operating speed compared with the bearing limiting speed, available space (outer diameter and width), and required precision grade from P0 to P2. Always apply a safety factor and verify that the calculated L10 service life meets your requirements.
What is the difference between open, shielded (ZZ), and sealed (2RS) bearings?
Open: No built-in protection, requires external sealing, and is suitable for clean environments or oil bath lubrication.
ZZ metal shields: Protect against dust and debris with low friction, making them suitable for high-speed applications, but they are not waterproof.
2RS rubber seals: Provide strong protection against dust and moisture. They are pre-greased and ideal for contaminated environments, but generate slightly more friction.
How often should I lubricate or replace the grease?
For general industrial use, grease should be replenished or replaced every 3,000 to 10,000 operating hours depending on speed, temperature, and environmental conditions. Bearings running above 70 C or in contaminated environments require shorter intervals. Sealed 2RS bearings are pre-greased for life and do not require re-lubrication.
What are the common causes of premature bearing failure?
The most frequent causes include inadequate or improper lubrication, contamination by dirt, dust, or moisture, incorrect installation, misalignment, excessive force during fitting, overloading beyond the rated capacity, improper shaft or housing fits, and fatigue at the end of normal service life.
How is the rated service life (L10) of a bearing calculated?
The basic L10 life is calculated as L10 = (C / P)^3 x 10^6 revolutions, where C is the dynamic load rating in kN and P is the equivalent dynamic bearing load in kN. It represents the number of revolutions that 90% of identical bearings will complete without fatigue failure. In practice, ISO 281 modified life calculations also apply correction factors for lubrication, contamination, material, and reliability.
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