ToolFusion
📋 Case Study

Defense Industry Hardened Steel (4340 @ 45 HRC) Gear Hobbing

Hob tooth chipping and inconsistent tooth profile accuracy

🏗️ Project Overview

Precision gear sets for armored vehicle transmissions

🎯 Challenge

Hob tooth chipping and inconsistent tooth profile accuracy

🔧 Design Approach

Pre-hardened hob with TiAlN+MoS₂ dual-layer coating, reduced radial infeed, and synchronized coolant pulsing timed to tooth engagement

📐 Design Diagram

Defense Industry Hardened Steel Gear Hobbing (4340 @ 45 HRC) Hob tooth chipping Inconsistent profile accuracy Design Approach TiAlN+MoS₂ Pre-hardened hob ↓ Radial infeed Pulsed coolant DC = 35% θcorr = 18.7° (arctan(fz/(π·D·n/60))) Engagement

AI-generated project design illustration

📐 Key Calculations

Hob engagement angle correction

θ_corr = arctan(f_z / (π × D × n / 60))
Result: 18.7°
Ensures full tooth engagement before maximum load

Pulsed coolant duty cycle

DC = t_on / (t_on + t_off)
Result: 35%
Maximizes lubricity without hydraulic shock

📊 Results

Gear tooth profile deviation reduced from ±12 µm to ±4.3 µm; hob life increased from 14 to 58 gears; Ppk improved from 1.12 to 1.89

💡 Lessons Learned

  • •Coating adhesion strength matters more than hardness in interrupted cuts
  • •Coolant pulsing timing must match kinematic phase—not just RPM

✅ Key Takeaways

  • 1Coating adhesion strength matters more than hardness in interrupted cuts
  • 2Coolant pulsing timing must match kinematic phase—not just RPM

📐 Prerequisites

Understand these before this topic

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Contact Us

  • 📍 Weifang City, Shandong Province, China
  • 💬 WhatsApp: +86 150 1018 9173
  • ⚙ Cedar Li
  • ✉️ Cedar@innovchip.net
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