Manufactured by CHG Bearing, the 638 is a precision Metric Miniature Deep Groove Ball Bearings. Key dimensional parameters include a 8 mm bore diameter, a 28 mm outer diameter, and a 9 mm overall width. This component is designed to meet standard load requirements and ensure consistent operational performance. For comprehensive technical evaluation, please explore the detailed specifications, dimensional data, product images, and CAD drawings provided below. A complete PDF data sheet is also readily available for direct download to support your engineering and procurement needs.
638 - Metric Miniature Deep Groove Ball Bearings
Technical Specifications
| Overview | |
|---|---|
| Part Number | 638 |
| Dimensions | |
| Bore Diameter (d) | 8 mm |
| Width (B) | 9 mm |
| Outer Diameter (D) | 28 mm |
| Open Width B | 9 mm |
| Radius rs min | 0.3 mm |
| Closed Width B1 | 9 mm |
| Performance | |
| Dynamic Load Cr (N) | 4563 N |
| Static Load C0r (N) | 1983 N |
| Grease Speed (x1000 rpm) | 28 x1000 rpm |
| Oil Speed (x1000 rpm) | 34 x1000 rpm |
| Design Configurations | |
| Open Model | 638 |
| Flanged Open Model | - |
| Shielded Model | 638ZZ |
| Flanged Shielded Model | - |
| 2RS | 2RS |
| 2RU | 2RU |
| TTS | - |
| Internal Design & Weight | |
| Cage Type | J |
| Ball Qty. Z | 7 |
| Ball Size Dw | 4.762 mm |
| Shielded Weight (g) | 30.3 g |
| Open Weight (g) | 28.1 g |
638 28 mm 8 mm 9 mm Frequently Asked Questions about 638 Metric Miniature Deep Groove Ball Bearings
Find key technical answers regarding dimensions, specifications, and replacement options for this model.
Yes, 100% of 638 Metric Miniature Deep Groove Ball Bearings leaving CHG Bearing production lines are subjected to multi-frequency Anderometer sound testing. All units satisfy baseline Z1V1 levels, with dedicated quiet-running electric motor quality (EMQ) lots certified to Z2V2 and Z3V3 standards for silent machinery integration.
Absolutely. The CHG Bearing 638 Metric Miniature Deep Groove Ball Bearings is a 1:1 direct interchange for renowned brands, matching part numbers: SKF 638, FAG 638, NSK 638. It shares identical envelope boundary dimensions, load capacities, and shaft fits, allowing instant drop-in replacement without retrofitting your machinery.
As standard production, CHG Bearing subjects 638 to precision bainite or martensite quenching, offering dimensional stability up to 120°C (248°F). For high-heat processing equipment, CHG Bearing also supplies custom S0 (150°C), S1 (200°C), or S2 (250°C) stabilization heat treatments upon request to prevent residual austenite transformation.
As a primary manufacturer, CHG Bearing supports both trial batch evaluations and container-load supply for 638. Standard catalog sizes are stocked for rapid 3–7 day dispatch, while high-volume OEM production runs typically dispatch within 30–45 days.
