71904 ACD/P4ADBD
71900 Series Super Precision Angular Contact Ball Bearings
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71904 ACD/P4ADBD Bearing Product Overview & Core Advantages
The 71904 ACD/P4ADBD is a super-precision duplex angular contact ball bearing designed for applications demanding exceptional rigidity and rotational accuracy. This matched back-to-back (DB) arrangement is preloaded to Class D (Heavy), providing superior stiffness and stability under complex combined loads (radial and axial). Manufactured to the stringent P4A tolerance class, it ensures minimal runout and is ideally suited for high-speed spindles and other high-precision machinery requiring reliable, long-term performance.
71904 ACD/P4ADBD Bearing Model Code Explained, Specifications & Naming Convention
- 71904: Basic designation denoting a super-precision, light series angular contact ball bearing with a 20mm bore.
- AC: Angular Contact design with a 25° contact angle.
- D: Indicates a Duplex (paired) bearing set.
- P4A: Denotes a super-precision tolerance class with specific running accuracy requirements.
- DB: Specifies the Back-to-Back mounting arrangement of the duplex pair.
- Heavy Preload (Class D): The bearings are preloaded to a heavy grade at the factory, ensuring maximum rigidity from installation.
71904 ACD/P4ADBD Bearing Structural Features & Performance Benefits
This bearing's performance is derived from its specific construction:
- High Rigidity & Stability: The back-to-back duplex arrangement creates a wide, rigid support system that effectively resists moment loads and shaft deflection, which is critical for high-precision machining.
- Superior Load Capacity: The 25° contact angle and heavy preload enable the bearing to handle significant combined radial and axial loads simultaneously.
- Optimized High-Speed Performance: The lightweight phenolic resin cage reduces centrifugal forces, while the precision-ground chrome steel components and optimized internal geometry contribute to a high limiting speed of 100,500 rpm.
- Precision Engineering: Adherence to the P4A tolerance class guarantees extremely tight dimensional and running accuracy, minimizing vibration and ensuring consistent performance.
71904 ACD/P4ADBD Bearing Typical Application Areas
The 71904 ACD/P4ADBD is engineered for the most demanding applications, including:
- Machine Tool Spindles: High-speed milling, grinding, and turning centers.
- Precision Spindles: PCB drilling, semiconductor manufacturing equipment.
- High-Frequency Motors: Spindles for routers and other high-RPM machinery.
- Robotics: High-accuracy joints and rotary actuators.
