What Is the MR126ZZ Bearing?
The MR126ZZ is a miniature deep-groove ball bearing engineered for precision, low-noise and long-life performance in compact mechanisms. It is manufactured from premium bearing steel (GCr15 / high-carbon chromium steel), with optional stainless steel (AISI 440C) for corrosive environments.
The model code breaks down as follows: “MR” is the manufacturer miniature series designation, “126” encodes the size envelope (bore x OD x width = 6 x 12 x 4 mm), and “ZZ” denotes double-sided metal shields (double-sided steel dust covers).
Key Features at a Glance
| Feature | Specification |
|---|---|
| Standard material | GCr15 bearing steel (high-carbon chromium) |
| Custom material | AISI 440C stainless steel (corrosion-resistant) |
| Dimensions | Bore 6 mm x OD 12 mm x Width 4 mm |
| Sealing | Double-sided metal shields (ZZ) |
| Accuracy class | P0 / P6 / P5 available |
| Limiting speed | Up to 40,000 rpm (grease lubrication) |
| Operating temperature | -20 to +100 degrees C (standard material) |
| Typical applications | Precision instruments, miniature motors, RC models |
Seal Type Reference
The “ZZ” in MR126ZZ stands for double-sided metal shields, delivering excellent dust protection:
| Seal type | Code | Dust protection | Lubrication retention | Suitable for |
|---|---|---|---|---|
| Open | – | None | Poor | Clean, enclosed environments |
| Single shield | Z | One direction | Fair | One-sided dust source |
| Double shield | ZZ | Both directions | Excellent | Dusty environments (recommended) |
| Rubber seal | VV / 2RU | Both directions | Very good | High-humidity environments |
MR126ZZ Specifications & Dimensions
All values below follow the original manufacturer data for the MR126ZZ. Bore diameter is 6 mm, outer diameter is 12 mm, and width is 4 mm. Verify these three figures against your housing and shaft drawings before ordering.
Basic Dimensional Parameters
| Parameter | Value | Unit | Tolerance (P0) |
|---|---|---|---|
| Bore diameter (d) | 6 | mm | 0 to -8 micrometers |
| Outer diameter (D) | 12 | mm | 0 to -11 micrometers |
| Width (B) | 4 | mm | 0 to -120 micrometers |
| Weight | approx. 2.1 | g | plus/minus 5% |
Technical Performance Parameters
| Performance parameter | Value | Unit | Notes |
|---|---|---|---|
| Basic dynamic load rating | 480 | N | Basis for fatigue-life calculation |
| Basic static load rating | 200 | N | Static load capacity |
| Limiting speed | 40,000 | rpm | Under grease lubrication |
| Material hardness | HRC 60-64 | – | After heat treatment |
| Lubrication | Grease | – | Lithium-based grease recommended |
| Seal type | ZZ | – | Double-sided metal shields |
Selection Guide: How to Choose the Right MR-Series Bearing
MR126ZZ vs. MR126Z – What Is the Difference?
Many buyers ask how MR126ZZ and MR126Z differ. The answer comes down to the shield configuration:
| Comparison | MR126Z | MR126ZZ |
|---|---|---|
| Number of shields | Single metal shield | Double metal shields |
| Dust protection | One-directional | Bidirectional |
| Dust-blocking capacity | approx. 60% | 95%+ |
| Protected side | One side | Both sides |
| Lubrication retention | Average | Excellent |
| Price delta | Baseline | +5-10% |
Buying advice:
- Choose MR126Z for relatively clean environments that need protection on only one side, such as enclosed motors.
- Choose MR126ZZ for dusty environments that require full protection, such as open power-transmission equipment.
Selecting by Accuracy Class
| Accuracy class | Application | Recommended |
|---|---|---|
| P0 (normal) | RC models, fans, general appliances | 4/5 stars |
| P6 (higher) | Motors, pumps, office equipment, instruments | 5/5 stars |
| P5 (precision) | High-precision machine tools, measuring devices | 4/5 stars |
Selecting by Seal Type
| Environment | Recommended model | Seal type | Reason |
|---|---|---|---|
| Clean and enclosed | MR126 (open) | None | Lowest friction, highest speed |
| General indoor | MR126Z | Single shield | One-sided protection, cost-effective |
| Dusty | MR126ZZ | Double shield | Full protection (recommended) |
| High humidity | Custom MR126VV | Rubber seal | Water/moisture resistant |
Material Selection Guide
Standard MR126ZZ bearings use GCr15 high-carbon chromium bearing steel:
| Property | GCr15 bearing steel | Notes |
|---|---|---|
| Hardness | HRC 60-64 | Excellent wear resistance |
| Strength | High | Suitable for higher loads |
| Machinability | Good | Easy precision machining |
| Price | Baseline | Best value |
| Corrosion resistance | Average | Anti-rust treatment needed |
For humid or corrosive environments, stainless steel (AISI 440C / SUS440C) is available as a custom option:
| Stainless steel grade | AISI 440C | 440C | SUS440C |
|---|---|---|---|
| Corrosion resistance | Excellent | Excellent | Excellent |
| Rust resistance | Inherent | Inherent | Inherent |
| Hardness | HRC 58-62 | HRC 58-62 | HRC 58-62 |
| Operating temperature | -30 to +120 degrees C | -30 to +120 degrees C | -30 to +120 degrees C |
| Price factor | +60-80% | +60-80% | +60-80% |
| Operating environment | Recommended material | Reason |
|---|---|---|
| Dry indoor | GCr15 bearing steel | High value, stable performance |
| General industrial | GCr15 bearing steel | Meets most requirements |
| Humid | Custom stainless steel | Prevents rust and corrosion |
| Food industry | Custom stainless steel | Meets hygiene requirements |
| Medical devices | Custom stainless steel | Resists sterilization corrosion |
Installation & Maintenance Tips
Installation steps:
- Clean and inspect – ensure shaft and housing are free of burrs and debris.
- Align center – keep the bearing perpendicular to the shaft axis.
- Press-fit gently – use proper tooling or a press; never strike the shields.
- Lubricate properly – fill roughly 30-40% with lithium-based grease.
- Shield orientation – for single-shield types, face the shield toward the dust source.
Daily maintenance:
- Check periodically for abnormal noise or vibration.
- Avoid overloading – keep load under 70% of the rated value.
- Keep the operating environment clean and dry.
- Replace the grease after about 5,000 operating hours.
Typical Applications
Thanks to its compact size, high precision and low noise, the MR126ZZ is widely used in:
- Precision instruments – measuring devices, optical instruments, laboratory equipment
- Miniature motors – servo motors, stepper motors, gear motors, cooling fans
- RC models and toys – RC cars, model aircraft, robot joints
- Office equipment – printers, scanners, copiers
- Home appliances – fans, vacuum cleaners, blenders
Cross-Reference & Interchangeability
The MR126ZZ size envelope (6 x 12 x 4 mm, double-shielded) is a widely standardized miniature bearing footprint, so equivalents exist across major global brands. When sourcing replacements or quoting alternates, the following part numbers describe the same MR-series miniature deep-groove ball bearing family:
| Brand | Typical designation | Notes |
|---|---|---|
| NMB | MR126ZZ (miniature series) | NMB is a leading Japanese miniature-bearing maker; its MR-series follows the same bore/OD/width coding. |
| NSK | MR126ZZ / miniature deep-groove | NSK miniature MR-series uses identical sizing conventions. |
| MinebeaMitsumi | MR126ZZ equivalent | Same parent group as NMB; MR-series interchange applies. |
| Generic / interchange | MR126ZZ, MR126-2Z, 6124-2Z | The “-2Z” or “ZZ” suffix denotes two metal shields; confirm dimensions before substituting. |
Related MR-series miniature bearings from the same size family:
| Model | Bore | OD | Width | Seal | Feature | Application |
|---|---|---|---|---|---|---|
| MR85ZZ | 5 mm | 8 mm | 2.5 mm | Double shield | Ultra-miniature | Miniature robotics |
| MR104ZZ | 4 mm | 10 mm | 3 mm | Double shield | Thin type | Ultra-thin devices |
| MR105ZZ | 5 mm | 10 mm | 3 mm | Double shield | Miniature | Small motors |
| MR106ZZ | 6 mm | 10 mm | 3 mm | Double shield | Thin type | Tight spaces |
| MR115ZZ | 5 mm | 11 mm | 4 mm | Double shield | Standard type | General equipment |
| MR105Z | 5 mm | 10 mm | 3 mm | Single shield | Low friction | High-speed use |
MR126ZZ vs. 608 Bearing
A common comparison: the 608 has an 8 mm bore and 22 mm OD, while the MR126ZZ has a 6 mm bore and 12 mm OD. The MR126ZZ is much more compact, suiting more miniaturized assemblies.
Frequently Asked Questions (FAQ)
Q1: What are the bore, OD and width of the MR126ZZ?
A: Bore 6 mm, outer diameter 12 mm, width 4 mm. This is a standard miniature bearing size conforming to GB/T 276.
Q2: What does “ZZ” mean on the MR126ZZ?
A: ZZ stands for double-sided metal shields. A single “Z” is one shield; “ZZ” is two shields, providing superior dust protection.
Q3: How much load can the MR126ZZ carry?
A: Basic dynamic load rating is 480 N; basic static load rating is 200 N. In service we recommend staying below 70% of the rated value – i.e. static load under roughly 140 N.
Q4: What is the maximum speed of the MR126ZZ?
A: The limiting speed is 40,000 rpm under grease lubrication. Open-type variants can run higher.
Why Source MR126ZZ Bearings From NLHB?
- Authentic materials – premium GCr15 bearing steel with full material test reports.
- Strict QC – every bearing is tested for speed, noise and vibration before shipment.
- Accuracy guaranteed – P0/P6/P5 available, with inspection certificates.
- Customization – stainless steel, special seals and accuracy classes on request.
- Fast shipping – standard models in stock, same-day dispatch.
- After-sales support – return or replacement on quality issues, plus technical selection guidance.
Need a quote on MR126ZZ bearings or a custom miniature bearing solution? Contact the NLHB team today.