Metric Size Standard Miniature Ball Bearings
Metric size standard miniature ball bearings are small single-row radial ball bearings measured in millimeters, designed for compact assemblies where shaft size, outer diameter and running accuracy must be confirmed precisely. This product list covers MR, SMR, 68, 69, 60, 62 and 63 series options from 0.6 mm to 9 mm bore, with open, ZZ shielded and 2RS sealed versions. Chrome steel and stainless steel options are available for different cost, corrosion and operating environment requirements. These bearings are commonly used in micro motors, robotics, medical tools, instruments, small fans, printers, scanners and precision mechanisms. TFL helps buyers match standard or custom alternatives based on bearing number, drawing, sample or application details.
Optimized for Miniature Applications
Good High-Speed Performance
Standard Metric Sizes for Interchangeability
Metric Miniature Ball Bearing Selection Guide
Metric miniature ball bearings are compact single-row radial ball bearings manufactured with millimeter dimensions and standard inner rings. This page covers MR, SMR, 68, 69, 60, 62 and 63 series miniature bearings. Compare bore size, outer diameter, width, open/ZZ/2RS design, material, radial load rating, speed and weight before requesting a quotation.
How to Choose This Bearing Type
Choose this category when your drawing specifies a small metric radial ball bearing without an outer-ring flange or extended inner ring. Start by confirming bore diameter, outer diameter, width, radial load, operating speed, sealing type, material, clearance and lubrication requirement.
If the design needs a flange for axial positioning, use metric size miniature flanged ball bearings. If the bearing number uses inch dimensions, compare inch size miniature ball bearings instead.
Metric vs Inch Miniature Ball Bearings: How to Identify
The main difference between metric and inch miniature ball bearings is the dimensional standard used for the bore, outer diameter and width. Metric miniature bearings use millimeter dimensions and common series such as MR, 68, 69, 60, 62 and 63, while inch miniature bearings use imperial sizing such as R-series numbers. Similar appearance does not guarantee interchangeability.
| Selection Item | Metric Miniature Bearings | Inch Miniature Bearings |
|---|---|---|
| Measurement System | Millimeter dimensions | Imperial dimensions |
| Common Examples | 608ZZ, 625ZZ, 694ZZ, MR137ZZ | R2ZZ, R188ZZ, R4ZZ |
| Common Series | MR, SMR, 68, 69, 60, 62, 63 | R and SR series |
| Replacement Method | Match bore, OD, width and bearing designation | Match original inch part number or confirm imperial dimensions |
Use a metric miniature ball bearing when the original drawing, shaft, housing or bearing designation is based on millimeter dimensions. Do not replace an inch miniature bearing with a metric bearing only because the size appears close, as small differences in bore, outside diameter, width or tolerance can affect fit, noise and service life.
Common Series and Model Range
| Series / Option | Typical Range | Selection Notes |
|---|---|---|
| MR / SMR series | Ultra-compact metric miniature bearings | MR series is commonly used for compact mechanisms, while SMR-style designations are often associated with stainless steel miniature bearing options. |
| 68 / 69 series | Thin-section metric miniature and small-size bearing series | Suitable where housing space is limited but speed and low friction remain important. |
| 60 / 62 / 63 series | Standard small-size metric bearing series | Selected when higher radial load capacity is needed within a compact bearing envelope. |
| Size coverage | 0.6 mm to 9 mm bore, 2.5 mm to 30 mm OD | Confirm bore, OD, width, load rating, speed and seal type before replacement. |
How to Read a Model Number: Example 694ZZ
In 694ZZ, “69” identifies the thin-section miniature bearing series, “4” indicates a 4 mm bore size, and “ZZ” means metal shields on both sides. This model has a 4 mm bore, 11 mm outer diameter and 4 mm width, making it a common example for compact metric miniature bearing selection.
Open vs ZZ vs 2RS Selection
Open bearings are suitable when the assembly allows external lubrication and the lowest running torque is preferred. ZZ shielded bearings help reduce dust entry while maintaining relatively low friction, making them common in small motors, fans and instruments. 2RS sealed bearings provide better contamination protection, but contact seals may increase starting torque and reduce practical speed in sensitive miniature applications.
Chrome Steel vs Stainless Steel Selection
Chrome steel is commonly selected for clean, dry applications where load capacity, availability and cost efficiency are important. Stainless steel miniature bearings are preferred when corrosion resistance, moisture exposure or cleaner operating conditions are required.
Stainless steel options may use designations such as “S” or “SMR” depending on the manufacturer. Always confirm material, lubrication and operating environment before replacement.
Key Specifications to Confirm Before Quotation
Before requesting a quote, confirm the part number, bore diameter, outer diameter, width, seal type, material, radial clearance, tolerance class, radial load, speed, temperature, lubrication and operating environment.
If you are replacing an EZO-style, NMB-style or other manufacturer-style miniature bearing number, send the current bearing code, drawing or sample photo so TFL can check dimensions and suffix details.
EZO / NMB-Style Replacement Notes
Many buyers source metric miniature bearings by original part number, cross-reference number or equipment replacement requirement. TFL can help compare dimensions, seal type, material, clearance and load rating before recommending a suitable replacement or alternative source.
Brand references and part numbers are used only for identification, replacement, interchange and cross-reference purposes. TFL does not imply original EZO, NMB or authorized distributor stock unless separately confirmed.
Common Applications
Metric miniature ball bearings are commonly used in micro motors, robotics, dental tools, medical devices, encoders, small fans, printers, scanners, drones, RC models, laboratory instruments, miniature pumps and compact automation equipment.
Selection should consider speed, noise, torque, contamination, corrosion risk and whether the bearing operates continuously or intermittently.
Popular Models / High-Demand Models
| Model Example | Typical Size / Feature | Common Buying Scenario |
|---|---|---|
| 608ZZ | 8 mm bore, 22 mm OD, ZZ shielded | High-demand metric small-size bearing for small motors, rollers and compact mechanisms. |
| 625ZZ | 5 mm bore, 16 mm OD, ZZ shielded | Used when a smaller 5 mm shaft bearing with moderate radial capacity is required. |
| 694ZZ | 4 mm bore, 11 mm OD, compact 69 series | Suitable for compact instruments, small motors and miniature precision assemblies. |
| S68/0.6 | 0.6 mm bore, stainless steel, open type | Used for ultra-small precision devices requiring extremely small metric bore sizes. |
| MR137ZZ | 7 mm bore, 13 mm OD, MR series | Compact MR-series option for lightweight instruments and small mechanical assemblies. |
Why Source from TFL
TFL helps customers source metric miniature ball bearings from qualified factory resources based on bearing number, drawing, sample or application requirements. Before shipment, we check model, quantity, appearance, packaging and basic quality requirements, then coordinate delivery to the customer.
Custom options, OEM requirements and customized packaging can be discussed according to model availability and order quantity.
Need Help Matching a Metric Miniature Bearing?
Send your bearing number, drawing, sample photo or application details. TFL can help confirm the series, dimensions, seal type, material and replacement options before quotation.
Request a QuoteTFL is a bearing supplier and sourcing partner. We provide replacement and alternative bearing options based on confirmed part numbers, drawings or application requirements; we do not claim to be the original brand or an authorized distributor of third-party brands.
FREQUENTLY ASKED QUESTIONS
How do I identify a specific metric miniature ball bearing?
- Bores＜10mm, the last digits in the model directly indicate the size in millimetres (e.g., model 684 has a 4mm bore);
- Bores≥10mm, the standard code rule "code × 5" applies (e.g., "00" in model 6200 corresponds to a 10mm bore).