Optimizing Aerospace Bracket Machining at Tier-1 Supplier in Wichita
Engineering Case Study
Scenario
A Tier-1 aerospace supplier in Wichita, Kansas, was tasked with high-precision milling of titanium alloy (Ti-6Al-4V) bracket components for a next-gen UAV airframe. Tight delivery windows, strict AS9100 traceability requirements, and limited spindle uptime on their legacy 5-axis CNC (Haas UMC-750) constrained the process. The shop floor team needed to validate whether a proposed feed rate increase—intended to reduce cycle time without compromising surface finish (Ra ≤ 1.6 µm) or tool life—was viable.
Given Data
- Length of cut: 245 mm
- Feed rate: 0.32 mm/rev (baseline) → tested at 0.45 mm/rev (proposed)
- Spindle speed: 850 rev/min (fixed due to Ti-6Al-4V chip load limits & machine torque curve)
- Time for tool changes: 0.75 min (due to manual tool presetting and verification)
- Non-cutting motions time: 0.82 min (complex 5-axis repositioning and probing)
Calculation
Using the CNC Cycle Time Estimator’s core formula:
Cutting Time = (Length of cut) ÷ (Feed rate × Spindle speed)
= 245 mm ÷ (0.45 mm/rev × 850 rev/min)
= 245 ÷ 382.5 ≈ 0.6405 min → 0.64 min (rounded to 2 decimals)
Total Cycle Time = Cutting Time + Tool Change Time + Non-Cutting Motions Time
= 0.64 + 0.75 + 0.82 = 2.21 min
(Baseline with 0.32 mm/rev yielded 245 ÷ (0.32 × 850) = 245 ÷ 272 = 0.90 min cutting time → total = 0.90 + 0.75 + 0.82 = 2.47 min)
Result and Decision
The estimator confirmed a 0.26-min reduction per part (10.5% cycle time improvement) with the higher feed rate. Post-validation runs verified no tool deflection, maintained Ra = 1.52 µm, and tool wear remained within 85% of expected life (measured via flank wear microscopy). The team adopted 0.45 mm/rev as the new standard for this operation, enabling a 12% increase in daily output without adding shifts or machines.
Lesson
Feed rate optimization must be validated against material-specific chip load envelopes—not just machine capability—and always cross-checked with real-world tool wear metrics, not just theoretical cycle time.