Thin-Wall Aerospace Housing — Distortion Control via Symmetric Machining
How symmetric stock removal, intermediate stress relief, and reduced radial engagement eliminated distortion on a 0.8mm wall thickness titanium aerospace avionics housing.
Case Facts
| Application | Aerospace avionics enclosure housing |
|---|---|
| Material | Ti-6Al-4V (Grade 5) |
| Processes | 5-axis-machining, cnc-machining, milling |
| Equipment | Mazak i700 5-Axis |
| Surface Finish | Ra 0.4 µm |
| Standards | AS9100D, ISO 2768-f |
| Quantity | 500 units/year |
| Tolerance | ±0.025 mm |
| Lead Time | 6-8 weeks |
Challenge
Thin-wall titanium housing with 0.8mm wall thickness required for an aerospace avionics enclosure. Initial machining trials resulted in 0.18mm distortion after unclamping due to residual stress relief and inadequate workholding rigidity. The part would not meet the ±0.025 mm flatness specification.
Solution
A three-phase approach: (1) Symmetric machining strategy — rough and finish both sides alternately to maintain balanced material removal; (2) Intermediate stress relief at 700°C for 2 hours in vacuum furnace after roughing; (3) Reduced radial engagement during finishing — 20% stepover with climb milling, using a 12mm carbide end mill at 0.5mm axial depth. Custom soft jaws with full-surface contact replaced 3-jaw chuck.
Result
Distortion reduced from 0.18mm to 0.03mm, exceeding the ±0.025 mm flatness specification. Surface finish maintained at Ra 0.4 µm. Cycle time increased 15% but scrap rate dropped from 40% to under 2%. Projected annual savings of $28,000.
Key Metrics
| Metric | Before | After |
|---|---|---|
| Wall Flatness (Before) | 0.18 mm | 0.03 mm |
| Scrap Rate | 40% | <2% |
| Surface Roughness | - | Ra 0.4 |
| Annual Savings | - | $28,000 |
| Cycle Time Impact | baseline | +15% |
Lessons Learned
- Thin-wall titanium parts (<1mm) require symmetric stock removal to prevent distortion
- Intermediate stress relief is essential for tight flatness requirements
- Full-surface contact fixturing eliminates localized deformation
- Climb milling with reduced radial engagement (<25%) minimizes cutting forces on thin walls