SF6902ZZ Stainless Steel Flanged Ball Bearing for Compact Robotic Mechanisms

The SF6902ZZ stainless steel flanged ball bearing is a compact, single-row deep groove ball bearing with an integrated flange on the outer ring. With a 15 mm bore, a 28 mm bearing outside diameter, and a 30.5 mm flange outside diameter, it is designed for mechanical assemblies where space-efficient bearing support and convenient axial positioning are important.

Manufactured with 440C stainless steel bearing rings, the SF6902ZZ can be considered for applications requiring corrosion resistance and compact rotating support. Its double metal shields help reduce the entry of dust and retain lubricant within the bearing. The integrated flange may simplify housing design and assembly in suitable applications.

This 15 mm bore flanged bearing can be evaluated for compact robotic mechanisms, finger linkages, small actuator supports, and other space-constrained mechanical assemblies. Actual suitability depends on the applied loads, operating conditions, mounting arrangement, and required service life.

SF6902ZZ Bearing Specifications

Parameter	Specification
Bearing model	SF6902ZZ
Bearing type	Single-row deep groove ball bearing
Flange type	Integrated outer-ring flange
Bore diameter (d)	15 mm
Bearing outside diameter (D)	28 mm
Flange outside diameter (DF)	30.5 mm
Bearing width (B)	7 mm
Flange thickness (BF)	1.5 mm
Bearing material	440C stainless steel*
Shield configuration	Double metal shields, ZZ
Lubrication	Grease lubricated*
Dynamic load rating	To be confirmed by BLH*
Static load rating	To be confirmed by BLH*
Limiting speed	To be confirmed by BLH*
Precision grade	Available options to be confirmed*
Internal clearance	Available options to be confirmed*

*Please contact BLH Bearing for the latest technical drawing, material specifications, load ratings, speed limits, and available customization options.

Key Features of SF6902ZZ Stainless Steel Flanged Bearings

Integrated Flange for Simplified Housing Design

The SF6902ZZ features an integrated flange on the outer ring. When matched with a suitable housing, the flange provides a locating surface that can simplify axial positioning and assembly. It may reduce the need for separate locating components in certain designs.

The flange is primarily intended for positioning and mounting. The housing, shaft, and bearing assembly must be designed to withstand the actual operating loads.

Compact 15 mm Bore and 28 mm Outside Diameter

With a 15 mm bore and a 28 mm bearing outside diameter, the SF6902ZZ offers a compact bearing format for space-limited assemblies. Its dimensions make it a candidate for small rotating mechanisms where radial space and component weight are important design considerations.

The bearing's compact size does not, by itself, determine the load capacity or service life of a complete robotic joint.

440C Stainless Steel Construction

440C stainless steel is commonly used for bearing components that require a combination of hardness, wear resistance, and corrosion resistance. The SF6902ZZ can be considered for applications where stainless steel construction is preferred over conventional chrome steel.

Corrosion resistance depends on the material condition, surface finish, operating environment, and maintenance practices. Stainless steel bearings should not be treated as completely corrosion-proof, especially in saltwater or aggressive chemical environments.

Double Metal Shields for Dust Protection

The ZZ configuration uses metal shields on both sides of the bearing. These shields help limit the entry of dust and other external contaminants while retaining grease inside the bearing.

ZZ shields are not equivalent to contact rubber seals and should not be treated as a waterproof sealing solution. The appropriate bearing closure depends on the contamination level, operating speed, temperature, and lubrication requirements.

Suitable for Selected Compact Robotic Mechanisms

The SF6902ZZ may be evaluated for compact robotic mechanisms that require a small flanged bearing, including:

Robotic finger linkages and dexterous hand mechanisms

Small wrist and forearm actuator supports

Compact rotary joints and linkage pivots

Auxiliary supports in robotic actuator assemblies

Small servo motor output-shaft support arrangements

These are potential application areas rather than a guarantee of suitability for every humanoid robot joint. Engineers should confirm the load, stiffness, mounting, and service-life requirements before selecting the bearing.

SF6902ZZ for Humanoid Robot Applications

Humanoid robots use a wide range of bearing sizes and configurations across their hands, arms, legs, actuators, and transmission systems. The appropriate bearing depends on the mechanical function, available installation space, load direction, and expected motion profile.

The SF6902ZZ may be suitable for selected lightweight or compact mechanisms, particularly where an integrated flange can simplify housing positioning.

Robotic Finger and Hand Linkages

In dexterous hand mechanisms, the SF6902ZZ can be considered for selected finger pivots, linkage shafts, and compact rotating supports. Its 15 mm bore may suit a shaft or pin of the corresponding design size, subject to proper shaft tolerances and bearing fit.

Finger joints may experience frequent reversals and varying loads. Bearing selection should account for oscillation angle, frequency, radial load, axial load, and required operating life.

Compact Wrist and Forearm Mechanisms

A small flanged bearing may be considered for auxiliary supports in compact wrist or forearm actuator assemblies. It can help support a rotating shaft when the bearing arrangement is designed for the actual loads and alignment requirements.

Where a reducer output experiences significant bending moments, engineers must assess bearing spacing, shaft deflection, housing stiffness, and the load capacity of the complete support arrangement.

Neck Rotation and Other Compact Joints

The SF6902ZZ may be evaluated for selected small neck rotation mechanisms or other compact rotary assemblies with appropriate loads. It should not be selected solely on the basis of its small size or nominal load rating.

Primary load-bearing joints that experience high overturning moments, shock loads, or substantial structural loads may require a different bearing arrangement, such as a larger-capacity bearing or a cross-roller bearing.

SF6902ZZ Bearing Selection Considerations

Before using an SF6902ZZ stainless steel flanged bearing in a robotic mechanism, consider the following factors.

Load Capacity and Bearing Life

The dynamic and static load ratings must be confirmed using the actual BLH product specification. Engineers should calculate the equivalent bearing load, expected bearing life, and static safety factor under the intended operating conditions.

For robotic joints, the applied overturning moment and bearing spacing may be as important as the nominal radial load. A bearing's catalog rating should not be treated as the allowable load for an entire robot joint.

Mounting and Flange Support

The integrated flange provides a convenient locating surface, but it is not a substitute for a properly designed housing and axial retention arrangement.

Check the following before assembly:

Shaft and housing tolerances

Bearing fit and installation method

Flange clearance and housing contact

Axial loads and shock loads

Housing stiffness and flange support

Alignment between the shaft and housing

Precision and Internal Clearance

Bearing precision and internal clearance should be selected according to the requirements of the complete mechanism. Higher bearing precision does not automatically eliminate backlash in a robot joint.

Internal clearance should be considered together with shaft and housing fits, temperature changes, thermal expansion, operating loads, and the required running characteristics. C2, normal clearance, or C3 should be selected only after reviewing the application conditions.

Lubrication and Operating Conditions

The correct grease and filling quantity depend on the bearing design, speed, temperature, load, and motion profile. For oscillating robotic mechanisms, starting torque, lubricant distribution, friction, and wear should be evaluated.

A ZZ-shielded bearing may reduce maintenance requirements in a suitable enclosed mechanism, but it should not be described as maintenance-free without supporting service-life evidence.

SF6902ZZ vs. F6902ZZ

The SF6902ZZ and F6902ZZ share the same basic 6902 flanged bearing size designation, but the material configuration may differ.

Feature	SF6902ZZ	F6902ZZ
Basic size	15 × 28 × 7 mm	15 × 28 × 7 mm
Flange outside diameter	30.5 mm*	30.5 mm*
Flange thickness	1.5 mm*	1.5 mm*
Flange structure	Integrated outer-ring flange	Integrated outer-ring flange
Material	Stainless steel version*	Chrome steel version*
Shield type	ZZ*	ZZ*

*Confirm the exact material, dimensions, and performance ratings for the selected supplier's version. The SF and F prefixes are not sufficient to establish every component material or performance specification across all manufacturers.

The stainless steel version may be preferred where corrosion resistance is important. The final choice should be based on the operating environment, load, speed, cost, and required service life.

Why Choose BLH Bearing?

BLH Bearing provides bearing solutions for industrial equipment and compact mechanical assemblies. For projects involving stainless steel flanged bearings or robotic mechanisms, customers can discuss their application requirements with the BLH technical team.

When requesting a quotation for SF6902ZZ, please provide:

Required bearing quantity

Shaft and housing dimensions

Radial and axial loads

Rotation speed or oscillation profile

Operating temperature

Environmental conditions

Required precision and internal clearance

Lubrication requirements

Expected service life

BLH can then review the application requirements and confirm the appropriate product configuration, technical specifications, and available options.

Frequently Asked Questions

What is an SF6902ZZ bearing?

SF6902ZZ is a stainless steel flanged deep groove ball bearing with double metal shields. The standard dimensions supplied for this model are a 15 mm bore, 28 mm bearing outside diameter, 30.5 mm flange outside diameter, and 7 mm bearing width.

Can SF6902ZZ be used in humanoid robots?

It may be suitable for selected compact robotic mechanisms, such as finger linkages, small rotary supports, and auxiliary actuator assemblies. Suitability depends on the actual load, motion, mounting arrangement, and required service life. It should not automatically be treated as a main-joint bearing.

What is the difference between SF6902ZZ and F6902ZZ?

The SF6902ZZ is generally used to identify a stainless steel version of the flanged 6902 bearing, while F6902ZZ commonly identifies a chrome steel version. Exact materials and specifications should be confirmed with the supplier.

Does ZZ mean the bearing is waterproof?

No. ZZ refers to double metal shields, which provide dust protection and help retain lubricant. ZZ shields are not designed to provide the same sealing performance as contact rubber seals.

Can the flange replace a retaining ring?

The integrated flange can provide a locating surface in a suitable housing and may reduce the need for a separate locating component. However, the flange does not automatically replace every axial retention feature. The assembly must be designed for the actual loads and installation conditions.

How should the internal clearance be selected for a robotic mechanism?

Internal clearance should be selected based on shaft and housing fits, temperature, loads, operating speed, and motion characteristics. C2 is not automatically the best choice for all robotic applications. Contact BLH Bearing for application-specific guidance.

How can I request a quotation for SF6902ZZ?

Contact BLH Bearing with the required quantity, application, dimensions, loads, operating conditions, and any precision or lubrication requirements. The technical team can confirm the available SF6902ZZ configuration and provide the relevant product information.