71909 CD/HCP4ADBA
Hybrid Ceramic Super Precision Bearings
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Main Dimensions
Ball & Washer Dimensions
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Materials
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71909 CD/HCP4ADBA Bearing Product Overview & Core Advantages
The 71909 CD/HCP4ADBA is a duplex back-to-back (DB) matched pair of super-precision angular contact ball bearings. Engineered for the most demanding applications, this set is characterized by its P4A tolerance class, ceramic balls, and phenolic cage. Its primary advantage lies in providing exceptional running accuracy, high rigidity, and superior high-speed performance, making it ideal for spindle systems requiring maximum precision and minimal thermal growth.
Model Code Breakdown
| Code Segment | Technical Meaning |
|---|---|
| 71909 | Basic bearing series and size designation (45mm bore, 68mm OD). |
| C | 15° contact angle. |
| D | Duplex Back-to-Back (DB) arrangement. |
| HC | Hybrid Ceramic: Indicates the use of ceramic balls. |
| P4A | Super-precision tolerance class, tighter than ABEC 7. |
| DB | Duplex Back-to-Back mounting (reiterated for clarity). |
| A | Extra light preload. |
71909 CD/HCP4ADBA Bearing Structural Features & Performance Benefits
Duplex DB Arrangement & High Rigidity: The back-to-back mounting creates a wide, stable support base, significantly increasing system rigidity and moment load capacity. This configuration is optimal for applications where shaft deflection must be minimized.
Hybrid Ceramic Construction: The use of silicon nitride (Si3N4) ceramic balls reduces centrifugal forces, lowers operating temperature, and extends bearing life. This material's lower density and non-conductive properties contribute to superior high-speed performance.
Super-Precision P4A Tolerances: Manufactured to the strictest P4A tolerance class, this bearing set ensures minimal runout and vibration, which is critical for achieving the highest levels of machining accuracy and surface finish.
Phenolic Cage & High-Speed Capability: The lightweight and robust phenolic resin cage is designed for high-speed operation, offering excellent strength and guidance with minimal friction. This, combined with the hybrid design, enables the high limiting speed of 41,000 rpm.
Preload & Running Accuracy: The bearings are supplied as a matched set with a predefined extra light preload (Class A). This eliminates internal clearance, enhances shaft positioning accuracy, and ensures consistent performance from startup.
71909 CD/HCP4ADBA Bearing Typical Application Areas
This high-performance bearing set is specifically designed for ultra-precise, high-speed machinery, including:
- High-Frequency Machine Tool Spindles (e.g., for milling, grinding, and drilling)
- Precision Grinding Spindles
- High-speed Robotic Drives and Servo Motors
- Aerospace and Defense Instrumentation
- Medical Device High-Speed Rotors
