W 638
W Series Stainless Steel Miniature Bearings
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Part No.
Part No.
W 638
Basic Information
Bearing type
Ball
System of measurement
Metric
Construction
Single Row
Weight
0.027 kg
Tolerance class
P0
Seal type
Open
For load direction
Radial
Main Dimensions
Bore diameter
8 mm
Bore diameter tolerance
-0.008mm to 0
Outside diameter
28 mm
Outside diameter tolerance
-0.009mm to 0
Width
9 mm
Width tolerance
-0.12mm to 0
Performance
Temperature range
-30° to 120 °C
Radial dynamic load rating
892 lbf
Radial static load rating
441 lbf
Limiting speed
40 X 1000 rpm
Lubrication
None
Radial internal clearance
CN
Materials
Ring material
Stainless Steel
Ball material
Stainless Steel
Cage material
Stainless Steel
Environment & Compliance
REACH
Compliant
ROHS
Compliant
Technical Drawings
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In Stock
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W 638 Bearing Product Overview & Core Advantages
The W 638 is a metric single row deep groove ball bearing engineered for high-performance applications requiring reliable radial load capacity. Constructed entirely from stainless steel, it offers excellent corrosion resistance, making it suitable for harsh environments. Its open design and P0 tolerance class ensure smooth operation and consistent performance, while its compact dimensions provide a space-saving solution for precision assemblies.
W 638 Bearing Model Code Explained, Specifications & Naming Convention
| Code Segment | Technical Meaning |
|---|---|
| W | Designates a stainless steel deep groove ball bearing. |
| 638 | Indicates the bearing size series, specifying an 8 mm bore, 28 mm outside diameter, and 9 mm width. |
| No Seal Suffix | The bearing is open, allowing for high-speed operation and custom lubrication schemes. |
| No Clearance Suffix | Standard CN radial internal clearance is applied. |
W 638 Bearing Structural Features & Performance Benefits
- All-Stainless-Steel Construction: The rings, balls, and cage are made from stainless steel, providing superior corrosion resistance and enabling use in washdown, chemical, and food-processing environments.
- Optimized Radial Load Capacity: The single row deep groove raceway geometry is designed to efficiently support radial dynamic loads up to 892 lbf and static loads up to 441 lbf.
- High-Speed Capability: The open design and precision-ground components minimize friction and heat generation, supporting a limiting speed of 40,000 rpm.
- Precision & Reliability: Manufactured to P0 tolerance class with tight dimensional control, ensuring consistent fit, smooth running, and long service life in demanding applications.
W 638 Bearing Typical Application Areas
This bearing is ideal for applications requiring compact size, corrosion resistance, and high-speed operation. Key sectors include:
- Medical and Dental Equipment: Handpieces, small pumps, and precision instruments.
- Food & Beverage Machinery: Conveyor rollers, mixers, and filling machines where washdown is frequent.
- Precision Mechanisms: Office automation equipment, small motors, and robotics.
- Chemical and Laboratory Apparatus: Pumps, agitators, and other equipment exposed to corrosive media.
