7228AC Angular Ball Bearing Heavy Duty High Load Capacity Bearing

7228AC Angular Contact Ball Bearing: Heavy-Duty, High-Precision Performance

Basic Parameters

• Bore diameter (d):140mm
• Outer diameter (D):250mm
• Width (B):42mm (single bearing); total thickness 84mm when mounted in pairs (e.g., DB/DF/DT configurations)
• Contact angle:25° (suffix "AC" indicates standard angular contact design)
• Weight:Approximately 12.5~13.2kg (single bearing)
• Structure:Single-row, non-separable design with inner/outer rings (with raceways), paired with balls and a cage. Cage options include solid brass (for high-speed stability) or bakelite (cost-effective).

Core Performance Specifications

1. Load Capacity
   • Dynamic load rating (Cr):228kN (typical value, e.g., NACHI 7228 bearing)
   • Static load rating (C0r):198kN (estimated based on size and load relationships)
   • Material:
     • Standard: GCr15/SUJ2 high-carbon chromium bearing steel (surface hardness of HRC58-62)
     • Optional: Stainless steel (SUS440C) or ceramic (Si3N4 balls + steel rings), available via customization
2. Speed & Precision
   • Limiting speed:
     • Grease-lubricated: 2,200rpm (standard type)
     • Oil-lubricated: 3,000rpm (optimized for heat dissipation)
   • Precision class:Standard P0; customizable to P4/P5 (e.g., SKF 7228 ACDGA/P4A for precision spindles)
3. Technical Features
   • Axial-radial load capability:
     • Single bearing: Supports radial loads and unidirectional axial thrust (requires paired mounting for bidirectional load capacity).
     • Mounting configurations: DB (back-to-back), DF (face-to-face), DT (tandem) to enhance rigidity and load distribution.
   • Stability design:Optimized raceway curvature and cage structure reduce friction and temperature rise during high-speed operation.

Structural & Environmental Adaptability

• Tolerance compatibility:
  • Shaft: H7/k6
  • Housing: J7
• Temperature range:
  • Standard: -20°C to 120°C
  • High-temperature type: Up to 300°C (requires ceramic materials + high-temperature grease)
• Sealing options:
  • Standard: Open (no seals)
  • Optional: 2RS (double rubber seals) or ZZ (double metal shields) with protection class IP54

Typical Applications

1. Industrial Machinery
   • Heavy-duty gearboxes: High-speed, heavy-load transmission systems in mining crushers and metallurgical rolling mills.
   • Large-scale motors: Support high-torque output for main shafts of chemical pumps or compressors.
   • Wind turbines: Pitch drive systems (1.5MW+ models) requiring corrosion resistance and impact resistance.
2. Transportation
   • Marine propulsion: Stainless steel (SUS440C) variants suitable for salt-spray environments in marine gearboxes.
   • Railway traction systems: Withstand axial vibration and radial loads from train motors.
3. Precision Equipment
   • CNC machine tool spindles: P4-class precision models provide rigid support for heavy-duty cutting.
   • Industrial robotics: Joint bearings for robotic arms, supporting high dynamic response and positioning accuracy.

Maintenance & Lubrication Guidelines

• Lubrication:
  • Grease: Lithium-based grease (NLGI 2) with 15%-20% filling volume; synthetic polyurea grease (temperature-resistant up to 200°C) recommended for high-temperature scenarios.
  • Oil: ISO VG 46-68 circulating oil for continuous high-speed operation to enhance heat dissipation.
• Re-lubrication interval:
  • Normal operating conditions: Every 8,000~12,000 hours (or calculated using the formula tf​=bf​A​, where A = speed × average diameter, and bf​ = bearing coefficient).
  • High-temperature/high-pollution environments: Shorten to 4,000 hours and enhance sealing protection.

Certifications & Compatibility

• Standards compliance:ISO 9001:2015, ISO 281 load standards
• Cross-brand compatibility:Interchangeable with models such as NACHI 7228 and SKF 7228 ACDGA.

Customization Options

1. Material Upgrades
   • Ceramic hybrid: Si3N4 ceramic balls + steel rings, with 15% higher dynamic load capacity, suitable for non-magnetic or high-frequency vibration scenarios.
   • Stainless steel: SUS440C material with corrosion resistance >1,000 hours in salt spray tests, ideal for food and pharmaceutical industries.
2. Special Configurations
   • Phosphating coating: Surface treatment reduces friction coefficient and extends wear life.
   • Laser-etched coding: High-precision marking supports Industrial Internet of Things (IIoT) equipment tracking.

Summary

The 7228AC angular contact ball bearing features large dimensions, high load capacity (228kN dynamic), and multi-scenario adaptability as core advantages, making it widely used in wind power, heavy machinery, and precision machining fields. Its standardized design and customizable features (e.g., materials, seals, precision) balance performance and cost. With scientific lubrication and maintenance, it delivers reliable long-term operation in extreme environments ranging from -20°C to 300°C.