Custom Bearings for Robotics: When Standard Bearings Are Not Enough

As robotics technology continues to develop, robotic systems are becoming smaller, lighter, faster, and more highly integrated.

This trend creates new challenges for bearing selection.

In many conventional industrial applications, a standard bearing can meet the requirements of the machine. However, robotic joints, integrated actuators, precision rotary mechanisms, and customized automation equipment may have strict requirements for dimensions, rigidity, accuracy, friction, speed, and service life.

When a standard bearing cannot fully match these requirements, a custom bearing may provide a more suitable solution.

A modern robotic joint may need to integrate a motor, reducer, encoder, brake, wiring, housing, and bearing into a very limited space.

The bearing must fit within this mechanical architecture while supporting the required loads and maintaining the required rotational performance.

Typical reasons for considering a custom bearing include:

• Non-standard dimensions

• Limited installation space

• Special shaft or housing interfaces

• Specific preload requirements

• Higher rotational accuracy

• Special sealing requirements

• Low-friction requirements

• High-speed operation

• Weight reduction

• Special lubrication requirements

• Integration with a reducer or actuator

Instead of forcing the robot structure to adapt to a standard bearing, customized bearing development allows the bearing to be designed around the application.

A custom bearing is not simply a standard bearing with a different outside diameter.

Depending on the application, customization may involve:

• Raceway geometry

• Rolling-element dimensions

• Internal clearance

• Preload

• Cage design

• Material selection

• Heat treatment

• Sealing

• Lubrication

• Accuracy class

• Surface finish

• Mounting configuration

Each parameter can affect bearing performance.

For example, changing preload may influence rigidity and rotational torque. Changing internal geometry may influence load distribution and service life. Changing sealing or lubrication may influence friction and operating temperature.

Therefore, customized bearing development should be based on the complete operating requirements.

The more application information a manufacturer receives, the easier it is to evaluate an appropriate bearing configuration.

Useful technical information may include:

• Radial load

• Axial load

• Moment load

• Static load

• Dynamic load

• Rotation speed

• Operating temperature

• Duty cycle

• Direction of rotation

• Vibration and shock conditions

• Shaft diameter

• Housing dimensions

• Available radial space

• Available axial space

• Mounting method

• Accuracy

• Runout

• Rigidity

• Friction torque

• Noise

• Expected service life

• Preload or internal clearance

Even if some parameters are not finalized during the prototype stage, preliminary information can help the bearing manufacturer develop an initial concept.

Humanoid robot joints are a particularly demanding application for precision bearings.

A single joint may need to combine compact dimensions, high torque, accurate positioning, low friction, and high mechanical rigidity.

Depending on the joint architecture, engineers may consider different bearing types, including:

• Crossed roller bearings

• Angular contact ball bearings

• Four-point contact bearings

• Thin-section deep groove ball bearings

For applications involving high moment loads and compact installation space, crossed roller bearings may be an appropriate option.

For more information about the technical characteristics of crossed roller bearings in robotic joints, see our article Crossed Roller Bearings in Humanoid Robot Joints: From Bearing Design to Joint Performance.

For an introduction to bearing selection for humanoid robot joints, see How to Choose a Precision Crossed Roller Bearing for a Humanoid Robot Joint.

Robotics applications are not limited to humanoid robots.

Customized bearings can also be used in:

• Robotic arms

• Collaborative robots

• Industrial robots

• AGV and AMR systems

• Semiconductor equipment

• Precision automation equipment

• Rotary positioning mechanisms

• Inspection equipment

• Medical automation

• Specialized actuators

Different applications can require completely different bearing characteristics.

For example, a high-speed precision actuator may prioritize low friction and rotational accuracy, while a robotic joint may place greater emphasis on rigidity, moment-load capacity, and compact dimensions.

Therefore, the bearing should be developed according to the application rather than selected only by model number.

For robotics companies, bearing development often begins with a prototype.

At this stage, the mechanical structure may still be changing.

The motor, reducer, housing, encoder, shaft, and bearing dimensions may all be optimized during development.

A suitable bearing supplier should therefore be able to support more than mass production.

A typical development process can include:

Application analysis → Bearing design → Prototype production → Testing → Design optimization → Validation → Mass production

Early communication between the robot manufacturer and bearing manufacturer can help identify potential mechanical issues before the design enters mass production.

Precision bearing performance depends on manufacturing consistency.

Important quality parameters may include:

• Raceway accuracy

• Roller or ball dimensional accuracy

• Roundness

• Runout

• Hardness

• Surface finish

• Internal clearance

• Preload

• Assembly quality

For high-precision applications, quality control should be considered throughout the manufacturing process rather than only during final inspection.

International standardization for rolling bearings is managed through ISO/TC 4 and related working groups. Applicable standards should be considered when defining dimensional, performance, testing, and life-related requirements.

Beining Intelligent Technology (Zhejiang) Co., Ltd., formerly Ningbo Beining Bearing Co., Ltd., was established in February 2013.

The company focuses on the research, development, and manufacturing of high-precision, low-noise, long-life, and high-speed bearings.

Beining's manufacturing facility covers more than 30,000 m² and is equipped with more than 100 automated bearing production lines.

The company has more than 200 employees, including more than 20 senior engineers, engineers, and master's-level technical professionals.

Its product portfolio includes:

• Precision crossed roller bearings

• Four-point contact bearings

• Angular contact ball bearings

• Thin-section deep groove ball bearings

• Miniature deep groove ball bearings

• Medium-size deep groove ball bearings

• Customized non-standard bearings

The company offers more than 400 bearing models and supports customized bearing development for different mechanical applications.

Not every application requires a custom bearing.

If a standard bearing can satisfy the required dimensions, load, speed, accuracy, and service life, it may be the most practical choice.

Customization becomes more relevant when the standard product cannot meet one or more critical requirements.

The objective should not be to customize a bearing simply because customization is possible.

The objective is to develop the most appropriate bearing solution for the actual application.

This approach can help balance:

• Performance

• Reliability

• Manufacturing feasibility

• Cost

• Service life

• Supply stability

For robotics and automation companies, a bearing supplier is not only a component supplier.

The manufacturer may also become an engineering partner during product development.

A capable supplier should be able to support:

• Technical communication

• Bearing selection

• Customized design

• Prototype development

• Sample production

• Quality control

• Mass production

• Production consistency

• Delivery planning

Beining combines bearing R&D, manufacturing, and customized production capabilities to support customers from initial bearing requirements through production.

For companies developing new robotic joints, actuators, or automation equipment, sharing the application requirements with the bearing manufacturer at an early stage can help determine whether a standard or customized solution is more appropriate.

As robotic systems become more compact and integrated, bearing requirements are becoming increasingly application-specific.

Standard bearings remain suitable for many applications, but customized bearings can provide greater flexibility when dimensional, accuracy, rigidity, friction, or integration requirements fall outside standard product ranges.

For humanoid robots, robotic actuators, industrial automation, and precision rotary mechanisms, the right bearing solution should be developed around the complete mechanical system.

With experience in precision bearing manufacturing and non-standard bearing development, Beining provides crossed roller bearings, angular contact ball bearings, four-point contact bearings, thin-section bearings, and customized bearing solutions for demanding applications.

If you are developing a new robotic joint or automation mechanism and need a customized bearing, provide the required dimensions, load, speed, accuracy, and operating conditions. Beining's engineering team can evaluate the application and recommend a suitable bearing configuration.