7028 CDGA/HCP4A
Hybrid Ceramic Super Precision Bearings
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Part No.
Part No.
7028 CDGA/HCP4A
Basic Information
System of measurement
Metric
Weight
2.83 kg
Tolerance class
P4A
Seal type
Open
For load direction
Angular Contact
Main Dimensions
Bore diameter
140 mm
Bore diameter tolerance
-0.004mm to 0
Outside diameter
210 mm
Outside diameter tolerance
-0.004mm to 0
Width
33 mm
Width tolerance
-0.2mm to 0
Contact angle
15 °
Ball & Washer Dimensions
Ball diameter
22.225 mm
Ball quantity
22
Performance
Temperature range
- 30°C to 110 °C
Radial dynamic load rating
34425 lbf
Radial static load rating
37350 lbf
Limiting speed
6.3 X 1000 rpm
Lubrication
Lubricated
Matched arrangement
Single
Number of bearings in matched set
3
Universal matching bearing
Universal Matchable (SU)
Preload
Extra light / Class A
Materials
Ring material
Chrome Steel
Ball material
Ceramic
Cage material
Phenolic
Technical Drawings
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In Stock
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Product Overview and Core Advantages
The 7028 CDGA/HCP4A is a high-precision angular contact ball bearing designed for demanding applications requiring exceptional accuracy and performance. This single bearing features an extra light preload (Class A) and is manufactured to P4A tolerance class, ensuring ultra-precise rotational characteristics. Its 15° contact angle is optimized to support combined radial and axial loads simultaneously. A key advantage is its universal matchable (SU) design, allowing it to be mounted in tandem, back-to-back, or face-to-face arrangements with other bearings from a pre-selected set to achieve specific stiffness and load requirements.
7028 CDGA/HCP4A Bearing Model Code Explained, Specifications & Naming Convention
The model number 7028 CDGA/HCP4A is decoded as follows:
- 7028: Basic series number, indicating a 140mm bore and 210mm outside diameter.
- C: Signifies a 15° contact angle.
- D: Indicates the use of a phenolic resin cage.
- GA: Denotes a universally matchable bearing with a specific preload group.
- HCP4A: A composite suffix where:
- P4A: Specifies the tolerance class, superior to ABEC 7/ISO P4, ensuring extremely tight dimensional and running accuracy.
- HC: Likely indicates the use of Hybrid Ceramic components (Ceramic balls with a steel ring).
Structural Features and Performance Benefits
- Hybrid Ceramic Construction: The combination of chrome steel rings and ceramic balls (Si3N4) significantly reduces friction, heat generation, and wear. This construction enables higher limiting speeds (6,300 rpm) and provides superior performance in lubricant-starved conditions compared to all-steel bearings.
- Phenolic Resin Cage: The D-designated cage offers excellent strength-to-weight ratio, low friction, and smooth operation at high speeds, contributing to the bearing's overall high-speed capability and stability.
- Exceptional Precision and Rigidity: Manufactured to P4A tolerance class with an extra light preload, this bearing provides minimal runout and high rotational accuracy. The preload eliminates internal clearance, resulting in high system rigidity and precise shaft positioning, which is critical for machine tool spindles and other high-precision equipment.
- High Load Capacity: With a dynamic load rating of 34,425 lbf and a static load rating of 37,350 lbf, it is engineered to handle significant combined loads.
7028 CDGA/HCP4A Bearing Typical Application Areas
This bearing is ideally suited for high-performance applications where speed, precision, and reliability are paramount. Key industries and equipment include:
- Machine Tool Spindles: High-speed milling, grinding, and turning centers.
- Precision Robotics: Arm joints and high-accuracy rotary axes.
- Aerospace & Defense: Gyroscopes, radar systems, and jet engine components.
- High-Frequency Motors and Spindles: Motors for PCB drilling and dental handpieces.
