Analysis and Prevention of Gear Tooth Surface Failures

Failure Modes and Their Prevention

1. Pitting of Tooth Surfaces

Repeated contact stress can cause metal particles to detach from the tooth surface, creating pits. This phenomenon is known as pitting.

• Cause: Contact stress exceeds the material’s fatigue limit; inadequate lubrication
• Characteristics: Initially small pits form on the tooth surface, which may progressively enlarge into extensive spalling
• Prevention: Raise tooth surface hardness to HRC 58 or above; select lubricating oil containing extreme pressure additives

2. Wear on Tooth Surfaces

Wear manifests as a reduction in tooth thickness, alteration of the tooth profile, and increased transmission noise. It typically results from poor lubrication or the ingress of external hard particles into the meshing zone. To mitigate wear, improve lubricant filtration and apply tooth surface hardening treatments.

3. Scuffing

Scuffing occurs under high speed and heavy load, where excessively high tooth surface temperature causes the lubricating film to rupture. Tear-like marks appear on the tooth surface. Preventive measures include using extreme pressure lubricating oil and applying phosphating or sulfiding treatment to the tooth surface.

4. Tooth Breakage

Overload impact or stress concentration at the tooth root can lead to cracks that propagate to complete fracture. Prevention strategies involve optimizing the tooth root fillet and performing shot peening strengthening at the tooth root.