To Clean or Not to Clean? A Practical Guide for New Machine Tool Spindle Bearings

You receive a new spindle bearing — it looks clean, maybe even greased. So, is it ready to install?

Not necessarily.

Many machine builders and maintenance engineers assume that the protective coating on new bearings is also functional lubrication. But in reality, this isn’t always the case. Improper handling of new spindle bearings can lead to:

• Reduced performance
• Increased noise and vibration
• Premature failure

This guide will help you make the right decision — whether to clean or not to clean — based on real-world experience and industry best practices.

Sealed vs. Open Bearings — Know What You're Dealing With

Do NOT Clean:

• Sealed or shielded bearings, which are often pre-lubricated with grease designed for both protection and operation.
• These bearings are shipped ready to install. Cleaning them risks removing essential lubricant or damaging the seals.

Must Clean:

• Open bearings coated only in rust-preventive oil.

Important: This type of oil is not a lubricant. It’s applied during storage and shipping to prevent corrosion. Leaving it in place can:

• Contaminate your spindle's lubrication system
• Reduce bearing performance
• Shorten service life

So yes — if you’re working with open bearings, cleaning before installation is strongly recommended.

 When Cleaning Is Even More Critical

Even sealed bearings may require cleaning under certain conditions:

1. Visible Contamination

If the bearing arrives with:

• Dust
• Metal particles
• Moisture or signs of corrosion

Cleaning (or replacement) is necessary.

2. High-Speed or Precision Applications

In high-performance machining centers or ultra-precision equipment, residual factory oils — even from “clean” bearings — can affect performance. Some shops choose to clean as an extra precaution.

3. Lubricant Incompatibility

If your spindle uses a specific grease different from any pre-applied lubricant (except dedicated dual-purpose grease), thorough cleaning is required to avoid mixing incompatible greases.

 How to Clean Spindle Bearings Properly (If Needed)

When cleaning is necessary, follow these steps carefully to avoid damage:

Step 1: Initial Degreasing

• Use a low-VOC solvent like kerosene.
• Submerge the bearing.
• Gently brush off heavy dirt or grease without rotating the bearing — spinning it now could scratch the raceways.

Step 2: Final Rinse

• Transfer the bearing to a fresh container of clean solvent.
• Now gently rotate it by hand while submerged to flush out fine particles.

Step 3: Dry Thoroughly

• Wipe dry with a lint-free cloth — medical-grade cotton works well.
• Or use filtered compressed air to blow off remaining solvent.
• Don’t leave the cleaned bearing exposed — proceed to lubrication quickly.

Step 4: Apply the Right Grease

• Use the manufacturer-recommended spindle grease.
• Never mix greases unless you know they are compatible.

Step 5: Final Check

• Rotate the bearing by hand — movement should be smooth and quiet.
• If there's roughness, noise, or play, stop and investigate — something may be wrong.

Final Thoughts: Small Steps, Big Impact

Cleaning new spindle bearings might seem like a minor step — but it plays a major role in ensuring long-term performance and reliability.

• Sealed bearings with dual-purpose grease? Install directly.
• Open bearings with rust-preventive oil? Clean before use.
• High-speed or precision applications? Extra care pays off.
• Lubricant mismatch? Can cause serious issues down the line.

By taking a few minutes to ensure proper cleaning and lubrication, you’re setting up your machine for smoother operation, less downtime, and longer life.

 Need Technical Support?

We understand how critical spindle performance is to your operations. If you have questions about spindle bearings, installation methods, or maintenance practices, our engineering team is here to help.

Beining Technology – Precision Bearings for Real Machines