🌐 Industry News
Gear Design & Manufacturing Enters the “Strength-Life Integration” Era
Modern gear transmission systems are shifting to full lifecycle design based on fatigue life prediction. ISO 6336:2024 further refines permissible stress coefficients for tooth contact and root bending, with stronger emphasis on surface integrity.
🔧 Technical Knowledge Points
Knowledge Point 1: ISO 6336 Gear Strength Verification — Contact vs Bending Dual Constraint
Gear design must satisfy both contact strength (σ_H ≤ σ_HP) and bending strength (σ_F ≤ σ_FP).
| Constraint Type | Core Formula | Key Coefficients | Failure Mode |
|---|---|---|---|
| Contact Strength | σ_H = Z_H·Z_E·Z_ε·√(…) | Z_H(zone), Z_E(elastic), K_Hβ(load dist.) | Pitting, wear |
| Bending Strength | σ_F = (F_t/(b·m_n))·Y_Fa·Y_Sa·… | Y_Fa(form), Y_Sa(stress), Y_ε(contact ratio) | Tooth breakage, cracks |
Engineering Insight: For 20CrMnTi carburized gear (m_n=3, Z=23/74, T=200N·m), ISO 6336 calculates contact stress ~720 MPa (allowable 1364 MPa) and bending stress ~258 MPa (allowable 667 MPa) — sufficient margins only if surface treatment meets standards.
Takeaway: Strength alone is not enough — surface integrity determines actual service life.
Knowledge Point 2: Shot Peening — A 5× Gear Fatigue Life Multiplier
Shot peening uses high-speed steel shots to create a residual compressive stress layer ≥800 MPa on tooth surfaces.
| Gear Type | Non-Peened Life | Peened Life | Improvement |
|---|---|---|---|
| 20CrMnTi Carburized | 2×10⁶ | 1×10⁷ | 5× |
| 40Cr Q&T | 1×10⁶ | 6×10⁶ | 6× |
Key Parameters (Geyontech Standard):
- Media: Cast steel shot φ0.6~1.2mm
- Almen intensity: 0.35~0.60 A (A-type strip for gears)
- Coverage: ≥100% (fluorescent/microscopic inspection)
- Caution: No heat treatment >250°C after peening
Key Technical Point: Almen intensity (N/A/C three strip types) is the gold standard: N=thin, A=general gears, C=heavy duty.
💡 Geyontech’s Differentiation Strategy
- Front-end integration: Include shot peening as standard in proposals
- Data-driven marketing: Embed 5× life data into materials
- ISO 6336 dual verification: Present “ISO 6336 × Shot peening” evidence
📎 Sources: Geyontech Knowledge Base — Gear Strength Calculation (GE-EN-001), Shot Peening Process