Miniature Ball Bearings Supplier
Miniature ball bearings are very small radial bearings (outer diameter usually <9 mm) used where space and weight are limited. They consist of hardened steel (or stainless/ceramic) inner and outer rings with miniature balls and a cage. These components are manufactured to tight (micrometer) tolerances, enabling high-speed, low-noise operation in precision equipment. In fact, miniature bearings “reduce friction and handle radial or axial loads in tight spaces” and are essential in devices from medical equipment to robotics and electronics. By standard definition, a miniature bearing has a nominal outside diameter below 9 mm.
BRK Bearings's miniature ball bearings are manufactured with high-quality materials (often chrome alloy or stainless steel) and tight tolerances (with precision grades up to ABEC 7 or 9), so that they have extremely low friction and torque, high rotational precision, and the ability to operate at very high speeds relative to their size.
At BRK Bearings, we provide the following series (stainless steel version also available):
- 600 Series (Extra Light) – Extra-light miniature bearings, starting from bore sizes 1 mm and up. Often used in precision instruments and compact devices
- 620 Series (Light) – Light-duty miniature bearings with slightly larger outer diameters for higher load capacity
- 630 Series (Medium) – Medium-duty miniature bearings. Larger and more robust than 60X/62X series
- 670 Series (Extra Thin) – Extra-thin section miniature bearings with very small cross-section. Ideal for space-limited applications
- 680 Series (Thin Section - Light) – Thin-section miniature bearings. Balance between load capacity and compactness
- 690 Series (Thin Section - Heavy Duty) – Thin-section but higher load than 68X series. Used in robotics, medical, and small motors
- R Series (Inch Series) - Standard inch-size miniature bearings. R followed by a number indicates fractional inch bore (e.g., R4 = ¼″ bore). Very common in North American markets
- TR Series (Thin Inch Series) - Inch-size thin section miniature bearings, less common than R-series but used in space-constrained mechanical systems
Miniature Ball Bearings
Check out our online product catalog of Miniature Ball Bearings with full specifications. We offer also free consultation and technical support to help you select the right bearing solution for your application, no matter the industry and application, and no matter whether you made the purchase or not.
Classifications, Standard Designations, and Design Variations
Miniature ball bearings are generally a subset of single-row deep groove ball bearings, distinguished mainly by their size. Each series is defined by a combination of bore size and cross-sectional profile (which determines load capacity and envelope). While many conform to ISO and ABMA nomenclature for deep groove ball bearings, some miniature types (especially R series) follow special conventions
Both Metric Series and Inch Series products can be offered in open, shielded, or sealed configurations for lubrication retention and contaminant protection. Letters like Z or ZZ indicate metal shields on one or both sides of the bearing, while RS/2RS (or RZ/2RZ) indicate rubber seals (contact or low-contact) on one or both sides
Metric Series (ISO-based)
- Basic Bearing Number (Type): Like standard deep groove bearings, most metric miniature ball bearings start with “6” (indicating single-row deep groove ball bearing, per ISO/ABMA)
- Basic Bearing Number (Size Series): The second digit indicates the general size series, which is related to the bearing’s robustness or cross-sectional size. Common series for miniature ball bearings are: 0 or 1 (extra light series, often marked as 60x or 61x), 2 (light series, 62x), 3 (medium series, 63x).
- Bore Size Code: The bore size is identified by the last part of the designation: for bore codes 00 to 03, standardized diameters are 10 mm, 12 mm, 15 mm, and 17 mm, respectively; from code 04 onward, the actual bore diameter is calculated by multiplying the code by
Inch Series (ABMA/ANSI R-Series Based)
-
Basic Bearing Number (Type): In the designation of miniature inch-series ball bearings, the letter "R" indicates that the bearing is part of the R-Series, which refers to standard single-row deep groove ball bearings with inch-based dimensions, as defined by ABMA standards.
-
Bore Size Code: The number following the "R" (e.g., R4, R8) typically represents the bore diameter in 1/16-inch increments. For example, an R4 bearing has a 4/16" (or 1/4") bore, and an R8 bearing has an 8/16" (or 1/2") bore
- Variants and Suffixes: The letters A and B following the R-series code indicate dimensional or structural variations—A typically means a larger outer diameter or different width (e.g., R4A), while B often signifies an alternate design such as an extended inner ring (e.g., R4B), used for specific mounting or load requirements
Precision Classes for Ball Bearings
BRK Bearings offer a huge selection of miniature ball bearings. Precision tolerances from ABEC-1 through ABEC-9 are generally available for most miniature ball bearing products.
- ABEC-1: Standard commercial bearings
- ABEC-3: Higher-quality commercial bearings
- ABEC-5: Precision grade
- ABEC-7: High precision instrument bearings
- ABEC-9: Super precision
Advantages and Performance Benefits
- Compact Size & Light Weight: Ideal for tight spaces and lightweight systems in electronics, medical, and aerospace. Bore sizes can go as small as 0.5 mm.
- Low Friction & High Speed: High-precision design enables low torque and very high RPMs, making them great for small motors and turbines.
- Radial & Axial Load Support: Can handle both radial and moderate axial loads, often eliminating the need for extra thrust bearings.
- High Precision & Low Noise: Tight tolerance classes (e.g., ABEC 5–9) reduce vibration and noise, ensuring smooth operation in precision equipment
- Low Starting Torque: Minimal friction enables smooth startup in delicate systems; optional low-torque cages and lubricants enhance this further.
- Long Service Life: With proper lubrication, miniature bearings last long and wear slowly, unlike plain bearings or flexural pivots
Applications of Miniature Ball Bearings
- Precision Instruments: Used in gyroscopes, encoders, and dial indicators for accurate, low-runout rotation.
- Medical & Dental Equipment: Essential for high-speed drills, pumps, and tools; stainless or ceramic bearings ensure hygiene and durability.
- Electric Motors & Blowers: Support rotors in fans, drones, and small motors, allowing higher speed and lower noise than bushings.
- Consumer Electronics: Enable smooth, quiet motion in HDDs, printers, fans, and vibration units in phones and gadgets.
- Robotics & Automation: Used in joints, servos, and small actuators of robots and automated machines for compact motion control.
- Automotive Systems: Found in motors for mirrors, seats, sensors, and hobby engines needing small, fast bearings.
- Industrial & Scientific Tools: Power small spindles, pumps, and lab devices needing precise micro-scale motion.
Your Reliable Bearing Partner
Our established network at BRK Bearings means that your company taps into a reliable supply chain. This gives your business a competitive advantage and helps you gauge production quotas. You will also experience quality assurance and fair pricing. Contact us for additional information.
have a question?
our experts can help
Our experts are here to assist with any bearing inquiries or custom solutions. Whether you need guidance on product selection, design consultation, or technical support, we're ready to help.
Call us at (425) 494-8394 or submit your inquiry, and we'll respond promptly!
Prefer to order online? Shop our storefront ›
*denotes a required field.