71821 ACD/P4DBA
71800 Series Super Precision Angular Contact Ball Bearings
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Part No.
Part No.
71821 ACD/P4DBA
Basic Information
System of measurement
Metric
Weight
0.64 kg
Tolerance class
P4
Seal type
Open
For load direction
Angular Contact
Main Dimensions
Bore diameter
105 mm
Bore diameter tolerance
-0.004mm to 0
Outside diameter
130 mm
Outside diameter tolerance
-0.004mm to 0
Width
26 mm
Width tolerance
-0.2mm to 0
Contact angle
25 °
Ball & Washer Dimensions
Ball diameter
7.144 mm
Ball quantity
35
Performance
Temperature range
- 30°C to 110 °C
Radial dynamic load rating
7898 lbf
Radial static load rating
12825 lbf
Limiting speed
16 X 1000 rpm
Lubrication
Lubricated
Matched arrangement
Duplex Back-to-Back (DB)
Number of bearings in matched set
2
Universal matching bearing
No (Standard)
Preload
Extra light / Class A
Materials
Ring material
Chrome Steel
Ball material
Chrome Steel
Cage material
Phenolic
Technical Drawings
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In Stock
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71821 ACD/P4DBA Bearing Product Overview & Core Advantages
The 71821 ACD/P4DBA is a duplex pair of metric precision angular contact ball bearings designed for the most demanding applications. This matched set in a Back-to-Back (DB) arrangement is preloaded to Extra light / Class A standards, delivering exceptional running accuracy and system rigidity. Its primary advantage lies in its ability to withstand combined loads—significant radial loads and thrust loads in both directions—simultaneously, making it ideal for high-precision, high-speed spindles requiring maximum stability.
71821 ACD/P4DBA Bearing Model Code Explained, Specifications & Naming Convention
| Code Segment | Technical Meaning |
|---|---|
| 71821 | Basic bearing designation, defining the core dimensions (105mm bore, 130mm OD, 26mm width). |
| AC | Angular Contact design with a 25° contact angle, optimized for high axial load capacity. |
| D | Indicates a duplex pair of two bearings supplied as a matched set. |
| P4 | Specifies a high-precision tolerance class (P4), ensuring ultra-precise rotational performance. |
| DB | Defines the Back-to-Back mounting arrangement, which provides high moment rigidity. |
| A | Specifies the Extra light preload level, minimizing friction for high-speed operation. |
71821 ACD/P4DBA Bearing Structural Features & Performance Benefits
- Superior Rigidity and Running Accuracy: The duplex DB arrangement creates a highly rigid bearing system that effectively resists moment loads, ensuring exceptional shaft positioning accuracy and minimal deflection under load. The P4 precision tolerance guarantees smooth, quiet, and vibration-free operation.
- Optimized High-Speed Performance: The phenolic resin cage is lightweight and possesses excellent sliding properties, contributing to lower centrifugal forces and reduced friction at the limiting speed of 16,000 rpm. The open design and factory-applied lubrication facilitate efficient heat dissipation.
- High Load Capacity: With a 25° contact angle and a high count of 35 precision balls, this bearing set offers a high dynamic load rating of 7898 lbf and a static load rating of 12825 lbf, enabling reliable performance under significant combined radial and axial loads.
- Premium Material Construction: Manufactured from chrome steel for both rings and balls, this bearing provides high hardness, wear resistance, and a long operational lifespan under demanding conditions.
71821 ACD/P4DBA Bearing Typical Application Areas
The 71821 ACD/P4DBA is engineered for high-performance machinery where precision, speed, and rigidity are paramount. Key application areas include:
- Machine Tool Spindles: High-speed milling, grinding, and turning centers.
- Precision Spindles: PCB drilling and routing spindles.
- High-Frequency Motors: Spindles for electric motors requiring high rotational accuracy.
- Robotics: High-precision joints and arm linkages.
