Metric Miniature Series Bearing Steel Bearings Manufacturers

Metric Miniature Series Range and Positioning

The Metric Miniature Series consists of metric-sized, single-row deep groove ball bearings made from bearing steel. The range is positioned between our smallest Metric MR classes and the larger inch R and thin-section families.

For very small metric bores with a different numbering system, compare the Metric MR Series. Our engineering team confirms the correct series after reviewing the shaft diameter, housing envelope and load conditions.

Application Fit and Operating Conditions

Metric miniature bearings appear wherever shaft diameters are small and radial space is limited. These bearing steel versions suit clean, oil- or grease-lubricated environments such as electric motors, gearboxes, printers, medical instruments, robotics joints, drones, flow meters and specialized industrial assemblies.

• Low noise and low vibration for audio equipment, medical devices and laboratory instruments.
• High-speed operation for spindle-type assemblies with light loads, using a matched cage and lubricant.
• Compact envelopes where the 68 series thin section saves radial space.
• Moderate load capacity where 60 and 69 series provide larger cross-sections and higher radial capacity.

For washdown, chemical or high-humidity environments, we recommend stainless steel miniature bearings instead of bearing steel. The same metric envelope can be supplied in our stainless steel bearing families.

Materials, Tolerances and Critical Specifications

Rings and balls are manufactured from high-carbon chromium bearing steel, ground and honed to control roundness, raceway curvature and surface finish. Because miniature rings are thin, heat treatment consistency is important to avoid distortion and maintain dimensional stability.

Critical specifications for the Metric Miniature Series include bore, outside diameter, width and chamfer dimensions, radial internal clearance, inner and outer ring running accuracy, noise or vibration grade, and the static and dynamic load ratings for the selected size. We use these parameters to confirm the bearing can survive the actual fit and operating conditions.

Configuration Options

All series can be configured around sealing, lubrication, cage and tolerance needs. The correct combination depends on speed, torque, temperature, contamination level and expected service life.

• Shields: non-contact metallic shields for low-torque, high-speed applications.
• Seals: contact or non-contact rubber seals for protection against contamination.
• Grease: base oil viscosity, operating temperature range and fill quantity are matched to the duty.
• Cages: steel or polymer formats depending on noise and speed requirements.
• Flanged OD: axial location can be provided through a flange on the outer ring.
• Modified bore or OD: custom dimensions for non-standard shafts and housings.

Quality Assurance and Acceptance Testing

YHU operates a closed-loop quality management system that starts at incoming material and continues through production and finished-batch inspection. Our factory uses high-precision testing equipment to verify dimensional accuracy, noise, vibration, sealing and surface condition. We hold IATF 16949, RoHS, CE and SGS certifications, allowing the same metric miniature range to be supplied under automotive and export compliance requirements.

During contract review, we confirm which reports are required. SGS test reports, dimensional data, noise and vibration results, and material traceability documentation can be included with delivery.

Engineering Support and Customization

As a National High-Tech Enterprise, YHU combines standard precision bearing production with non-standard bearing development. We can design and optimize the bearing structure, material and performance parameters for specific industries such as motors, medical equipment, semiconductor tools and aerospace. OEM and ODM projects are supported from drawing or sample through prototype production, mass delivery and after-sales technical support, including failure analysis.

The same Metric Miniature Series platform can be adapted with modified bore or outside diameter, flanged outer rings, special cage materials, alternative seals, customized grease and defined internal clearance. That approach turns a standard miniature bearing platform into an application-specific component.

Installation and Maintenance Notes

Miniature bearings are sensitive to mounting method and fit. Press on the ring with the interference fit, never through the balls, and avoid direct impact. Bore-to-shaft and outside-diameter-to-housing interference will reduce radial internal clearance, so the specified clearance should account for the actual fits and operating temperature.

For grease-lubricated bearings, keep the fill quantity within the recommended range and use a grease matched to the speed and ambient temperature. Bearings should stay in their original packing until assembly, and clean handling with gloves avoids corrosion and contamination.

Frequently Asked Questions

What is the Metric Miniature Series?

The Metric Miniature Series is our bearing steel deep groove ball bearing range in metric dimensions, mainly the 68, 60 and 69 series. These compact bearings are used where the envelope is small but the assembly still needs the running accuracy of a full deep groove ball bearing.

How do I choose between 68, 60 and 69 series?

Selection depends on envelope and load. The 68 series offers the thinnest section for minimum radial space, the 60 series provides a balanced section for general small-motor duty, and the 69 series adds a larger ball complement for higher capacity in a compact package. We confirm the choice after reviewing load, speed and available space.

Can these bearings be supplied with shields, seals and special grease?

Yes. We configure ZZ shields or 2RS seals, cage material, grease type and fill quantity according to torque, speed, temperature and noise requirements.

Can you produce non-standard versions based on our drawing?

Yes. Our engineering team supports OEM and ODM customization from drawings or samples. We can modify bore, outside diameter, width, flange features, clearance, sealing and lubrication, and produce prototype samples before serial mass production.

What quality documentation is available?

Deliveries can include dimensional inspection data and material traceability. SGS test reports, IATF 16949, RoHS and CE certificates are available for the relevant product scope.

Are bearing steel miniature bearings suitable for washdown or corrosive environments?

Bearing steel is best for clean, lubricated applications. For washdown, chemical or high-humidity conditions, the stainless steel bearing range is the better choice and can be supplied in equivalent metric miniature sizes.