71908 ACD/HCP4A
Hybrid Ceramic Super Precision Bearings
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Basic Information
Main Dimensions
Ball & Washer Dimensions
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71908 ACD/HCP4A Bearing Product Overview & Core Advantages
The 71908 ACD/HCP4A is a high-precision angular contact ball bearing engineered for applications demanding exceptional accuracy and performance. This single-row bearing is distinguished by its 25° contact angle and is supplied with a preload, ensuring high system rigidity and minimal axial/radial runout from the moment of installation. Manufactured to a P4 (ABEC-7) tolerance class, it guarantees superior rotational accuracy. The combination of a phenolic cage and ceramic balls enables outstanding high-speed performance, with a limiting speed of 38,000 rpm, while also offering reduced weight and superior resistance to thermal expansion.
Model Code Breakdown
| Code Segment | Technical Meaning |
|---|---|
| 71908 | Basic bearing series and size designation (40mm bore, 62mm OD, 12mm width). |
| AC | Angular Contact design with a 25° contact angle. |
| D | Signifies a high-precision design. |
| HC | Hybrid Ceramic: Indicates the use of ceramic balls (typically Silicon Nitride, Si3N4). |
| P4 | Specifies the tolerance class P4 (ABEC-7), denoting very high precision. |
| A | Indicates that the bearing is supplied with a preload for immediate high rigidity. |
71908 ACD/HCP4A Bearing Structural Features & Performance Benefits
- High Rigidity and Precision: The 25° contact angle and factory-applied preload work in tandem to deliver exceptional system stiffness and precise shaft positioning, critical for minimizing deflection under load.
- Superior High-Speed Capability: The lightweight phenolic resin cage offers excellent strength-to-weight ratio and centrifugal stability. Combined with low-density, hard ceramic balls, this significantly reduces centrifugal forces and friction, enabling reliable operation at the high limiting speed of 38,000 rpm.
- Enhanced Durability and Life: Ceramic balls are electrically insulating, harder, and smoother than steel, leading to reduced wear, longer service life, and improved resistance to lubrication starvation.
- Optimized for Combined Loads: The angular contact design is inherently capable of supporting combined loads (simultaneous radial and axial loads), making it an ideal choice for applications with complex loading conditions.
71908 ACD/HCP4A Bearing Typical Application Areas
The 71908 ACD/HCP4A is designed for the most demanding high-speed and high-precision machinery, including:
- Machine Tool Spindles: High-speed milling, grinding, and turning centers.
- Precision Spindles: PCB drilling and routing spindles.
- High-Frequency Motors: Spindles for CNC routers and engraving machines.
- Aerospace and Instrumentation: Gyroscopes, navigation systems, and other precision instruments.
