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Helped a Vacuum Motor Customer Lower Bearing Noise from 48dB to 42dB
Sep 30, 2026 0 Dreampower
A practical case study on improving bearing precision, vibration performance, lubrication consistency, and noise stability for vacuum motors.
The Situation
A vacuum motor factory in Suzhou was having trouble with bearing noise.
They produce about 2 million motors per year for well-known vacuum brands. Their customers closely monitor motor noise, and motors that exceed the required noise level may be rejected during inspection.
The factory was using 6201 bearings, but the noise performance was inconsistent. Some batches measured around 45dB, while others reached 49dB, with an average of approximately 47dB.
The bearing noise was not necessarily extremely high, but the batch-to-batch variation was too large. This occasionally caused problems during export inspection.
Customer Request
They wanted something quieter. More importantly, they wanted more consistent performance.
What We Found
We asked the customer to provide samples of their current bearings and carried out a detailed inspection. Nothing was dramatically wrong with the bearings. However, several small factors were working together to increase noise and vibration.
| Parameter | Original Bearing | Issue |
|---|---|---|
| Ball Grade | G16 | Roundness variation contributed to irregular vibration |
| Raceway Finish | Ra 0.12 | A relatively rough surface added friction-related noise |
| Grease Fill | Inconsistent | Some bearings had too much grease, while others had too little |
| Vibration Grade | ZV2 | Barely sufficient for this type of vacuum motor application |
Individually, these issues were relatively small. Together, however, they resulted in higher and less stable bearing noise.
Our Solution
Based on the application requirements, we proposed a different specification:
The main improvements focused on ball quality, raceway surface finish, grease consistency, and vibration performance.
| Parameter | Original | Our Bearing |
|---|---|---|
| Ball Grade | G16 | G10 |
| Raceway Finish | Ra 0.12 | Ra ≤ 0.08 |
| Grease Fill | Inconsistent | ±2%, low-noise grease |
| Vibration Grade | ZV2 | ZV3 |
Consistency was important to us. We did not select special samples for testing. Instead, we sent 200 pieces directly from our normal production line so the customer could evaluate what we could consistently deliver.
The Results
The customer tested both bearings in their own noise laboratory.
| Metric | Original Bearing | Our Bearing (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 |
Average noise dropped by approximately 5 dB, while batch variation was reduced from ±1.5 dB to ±0.6 dB.
Customer Feedback
“The motor sounds much quieter now. That sandy noise is gone.”
Long-Term Result
The customer then conducted a 3-month trial involving more than 5,000 bearings. No noise complaints were reported during the trial.
- More than 5,000 bearings tested during the 3-month trial
- No noise complaints reported
- Current purchase volume: approximately 20,000 pieces per month
- The customer also introduced us to another motor factory within their group
What You Can Learn From This Case
If you are a motor manufacturer dealing with bearing noise, these are four areas worth checking:
G10 vs. G16 can make a measurable difference in vibration and noise performance.
A smoother raceway, such as Ra ≤ 0.08, can help reduce friction-related noise.
Consistent grease quantity and suitable low-noise grease help maintain stable performance.
Higher vibration performance can be considered for applications where motor noise is especially critical.
Nothing fancy. Just better control of the details.
For quiet motor applications, small improvements in bearing quality and consistency can make a meaningful difference.
