How to Choose the Right Spacer for a Bearing

In mechanical assemblies, spacers are small but essential components that ensure correct positioning and alignment of bearings. They play a key role in maintaining the axial clearance, supporting proper load distribution, and preventing premature wear. Choosing the right spacer for a bearing means improving precision, performance, and durability in industrial systems.

Here’s a practical guide to help you make the best choice.

1. Understanding the Function of a Spacer

A bearing spacer is placed between two components—often between bearings or between a bearing and a housing shoulder—to set the correct distance and avoid unwanted axial loads. Its main functions include:

• Maintaining parallel alignment of bearing rings.
• Distributing axial forces evenly.
• Compensating for thermal expansion or machining tolerances.
• Preventing mechanical stress during operation.

By using the proper spacer, you can reduce vibration, increase bearing life, and improve system efficiency.

2. Choosing the Right Material

The material of the spacer must be compatible with the bearing type, load conditions, and working environment. Common materials include:

• Stainless steel – Resistant to corrosion and ideal for humid or aggressive environments (e.g. food and pharmaceutical industries).
• Carbon steel – Offers high strength for heavy-duty applications.
• Brass or bronze – Provide low friction and good machinability.
• Aluminum – Lightweight and suitable for low-load applications.
• Technical plastics (PTFE, POM, nylon) – Excellent for insulating, lightweight, or low-noise applications.

✅ Tip: When bearings operate in corrosive or high-moisture environments, stainless steel spacers (AISI 304 or 316) are the best option.

3. Determining the Correct Size and Tolerance

Choosing the right dimension is crucial for precision assembly. The spacer’s inner and outer diameter must perfectly match the bearing geometry, while the length determines the correct axial distance.

❌ Mistake: Using a spacer that is too short or long can cause misalignment or excessive preload.
✅ Solution: Always refer to the bearing manufacturer’s data sheet or use calibrated precision spacers with controlled tolerances (e.g. ±0.01 mm).

4. Considering the Application Type

Different mechanical systems require specific spacer designs:

• Axial spacers: Keep bearings aligned along a shaft.
• Radial spacers: Maintain the correct gap within housings.
• Adjustable spacers: Allow for fine tuning during assembly.

For high-speed or high-precision systems (such as electric motors or transmissions), it’s recommended to use ground and balanced spacers to avoid vibration and improve performance.

5. Thermal and Mechanical Considerations

Temperature variations can affect the performance of both bearings and spacers. Materials expand differently under heat, potentially altering the preload.

✅ Tip: In high-temperature applications, select materials with a similar expansion coefficient to the shaft and housing. For example, using steel spacers with steel components ensures dimensional stability during temperature changes.

6. Assembly and Maintenance

Correct installation is as important as the choice itself.

• Clean all contact surfaces before mounting.
• Avoid excessive tightening that can deform the spacer.
• Check alignment after assembly with measuring tools.
• Replace worn or deformed spacers during maintenance.

A small imperfection can affect the entire bearing system’s precision and lifespan.

Conclusion

Selecting the right bearing spacer requires attention to material, dimension, tolerance, and operating conditions. A well-chosen spacer ensures correct alignment, reduces mechanical stress, and extends the life of the bearing and surrounding components.

At Bearing Tools, we supply a wide range of precision spacers made from stainless steel, brass, aluminum, and technical polymers — all designed for durability, corrosion resistance, and high accuracy. Whether for industrial, automotive, or food-processing applications, our spacers guarantee optimal performance and reliability in every configuration.