Case Study: How We Helped a Vacuum Motor Customer Lower 6201 Bearing Noise from 48dB to 42dB

Welink Bearing Factory

The Challenge: Unstable Noise in Vacuum Motor Bearings

A vacuum motor factory in Suzhou was struggling with unstable bearing noise. They produce roughly 2 million motors annually for major vacuum brands, meaning any motor exceeding strict noise limits faces immediate rejection.

They were using standard 6201 bearings, but the noise levels were inconsistent. While the average was around 47dB, some batches measured 45dB, and others spiked up to 49dB. This lack of stability caused occasional failures during export inspections. The client urgently needed a quieter, more consistent bearing solution.

The Root Cause: Micro-Issues Adding Up

We asked for samples of their current bearings and disassembled them in our lab. We found that while there were no catastrophic flaws, several small issues compounded to create loud, unstable noise:

Parameter	Original Bearing	The Issue
Ball grade	G16	Roundness was off, causing irregular vibration
Raceway finish	Ra 0.12	Slightly rough, adding friction noise
Grease fill	Inconsistent	Some had too much, some too little
Vibration grade	ZV2	Barely adequate for high-speed vacuum motors

The Welink Solution: Upgrading the Details

We proposed upgrading to a different specification: 6201 ZZ, P6, ZV3. Here is exactly what we optimized:

Parameter	Original Spec	Welink Bearing Spec
Ball grade	G16	G10
Raceway finish	Ra 0.12	Ra ≤ 0.08
Grease fill	Inconsistent	±2% tolerance with low-noise grease
ibration grade	ZV2	ZV3

A Note on Testing: We didn't hand-pick special "golden" samples. We sent 200 pieces straight from our standard production line because we wanted the client to see what we can deliver consistently.

The Results: 5dB Drop and Stabilized Quality

The customer tested both bearings in their own independent noise lab. The key outcome: average noise dropped by about 5dB, and batch variation was cut by more than half.

Metric	Original Bearing	Welink 6201 ZZ ZV3
Noise range	46 – 49 dB	41 – 43 dB
Average noise	47.2 dB	42.1 dB
Batch variation	±1.5 dB	±0.6 dB

One of their senior engineers noted:

"The motor sounds much quieter now. That sandy noise is gone."

Long-Term Impact: Following a successful 3-month trial using 5,000+ bearings with zero noise complaints, the client now orders approximately 20,000 pieces monthly. Furthermore, they have officially introduced Welink Bearing to another motor factory within their group.

4 Key Takeaways for Motor Manufacturers

If you are a manufacturer dealing with electric motor bearing noise, check these four critical details:

• Ball grade matters: Upgrading from G16 to G10 can alone make a 2–3dB difference.

• Refine the raceway finish: An Ra 0.08 finish significantly outperforms 0.12 in reducing friction.

• Strict grease control: Grease needs to be consistent—the exact same amount every time.

• Upgrade to ZV3: It is highly worth the investment for quiet applications like vacuum motors.

That's it. Nothing fancy. Just better control of the manufacturing details.

Want to test our low-noise bearings on your motor assembly line? Contact us at sales@welinkbearing.com for free samples. Your test samples will be supplied within 7 days after your quality requests are confirmed.