📋 Case Study

Defense Contractor Inconel 718 Turbine Blade Root Machining

Micro-cracking at root fillets due to localized thermal stress and residual tensile stress

🏗️ Project Overview

CNC milling of turbine blade root dovetails in Inconel 718 for jet engines

🎯 Challenge

Micro-cracking at root fillets due to localized thermal stress and residual tensile stress

🔧 Design Approach

Cryogenic cooling integration, low-heat toolpath sequencing (climb → conventional → rest-milling), and post-machining compressive stress induction via laser peening simulation

📐 Design Diagram

AI-generated project design illustration

📐 Key Calculations

Heat Affected Zone Depth

k × √(t / ρ·c)

Result: 0.18 mm

Must remain < 0.15 mm to avoid microcrack nucleation

Residual Stress Threshold

0.7 × Yield Strength

Result: 840 MPa

Target compressive stress to offset tensile peaks

📊 Results

Zero micro-cracks detected in 100% inspection, cycle time reduced 19% via optimized heat management, fatigue life increased 3.1×

💡 Lessons Learned

• •Thermal gradient control is more critical than raw MRR in superalloys
• •Sequential toolpath strategy directly governs residual stress distribution

✅ Key Takeaways

• 1Thermal gradient control is more critical than raw MRR in superalloys
• 2Sequential toolpath strategy directly governs residual stress distribution