1. Lubrication Problems

• Contaminated grease → Replace with clean, high-quality lubricant.

• Insufficient lubrication (low oil level/seal leakage) → Refill or repair seals.

• Water, acid, or paint contamination → Flush and replace lubricant.
  
  

2. Bearing Installation & Fit Issues

• Excessive or insufficient clearance (manufacturing defect) → Replace with properly sized bearings.

• Loose shaft fit (undersized shaft/unsecured adapter) → Re-machine shaft or tighten sleeve.

• Over-tightened bearing → Adjust preload to recommended specs.

• Misaligned/damaged housing (oval or distorted bore) → Correct housing roundness or replace.
  
  

3. Mechanical Damage & Wear

• Abrasive particles (sand, carbon) → Clean housing, replace bearings.

• Corrosion or rust → Use moisture-resistant grease, improve sealing.

• Cage fracture → Replace bearing immediately.

• Ball/roller wear or pitting → Check for misalignment or overload; replace bearing.
  
  

4. Assembly & Structural Issues

• Seal friction (misaligned/eccentric seals) → Realign or replace seals.

• Excessive axial load (improper bearing arrangement) → Use correct fixed/floating bearing setup.

• Shaft/housing shoulder interference → Machine to proper dimensions.

• Resonance/vibration → Reinforce base, add damping pads.
  
  

5. Thermal & Operational Failures

• Overheating (tight fit, poor lubrication) → Ensure proper clearance and oil flow.

• Thermal expansion mismatch → Allow for axial play in shaft design.

• Burning/discoloration (from forced heating) → Use induction heaters for installation.

Preventive Measures

• Regular inspections (noise, temperature, vibration).

• Proper tools (avoid hammer strikes during installation).

• High-quality replacements (match OEM specs).