Aerospace engineering demands materials that combine lightweight performance, durability, and high-temperature resistance. Two standout materials in this sector are Titanium alloys and PEEK (Polyether Ether Ketone). Both bring unique benefits and machining challenges that require precision, advanced tooling, and expertise.
For manufacturers seeking high-quality machining of these demanding materials, Boona Prototypes provides advanced CNC machining, rapid prototyping, and small-batch production services, ensuring aerospace-grade results.
I. Material Properties: Titanium vs PEEK
Titanium and PEEK serve very different roles in aerospace but share one similarity: both are difficult to machine without proper strategies.
Table 1. Comparison of Titanium vs PEEK Properties
| Property | Titanium Alloy (Ti-6Al-4V) | PEEK (Unfilled) |
|---|---|---|
| Density (g/cm³) | 4.43 | 1.30 |
| Tensile Strength (MPa) | ~900 | ~100 |
| Elastic Modulus (GPa) | 110 | 3.6 |
| Melting Point (°C) | 1660 | 343 |
| Continuous Use Temp (°C) | 400+ | 250 |
| Corrosion Resistance | Excellent | Excellent (chemicals, solvents) |
| Machinability | Poor–Moderate (hard on tools) | Moderate (heat sensitive) |
Key Insight: Titanium offers exceptional strength-to-weight ratio, while PEEK is a lightweight polymer ideal for non-structural aerospace parts requiring chemical resistance.
II. Machining Challenges
Titanium
-
Low thermal conductivity causes heat buildup.
-
Work-hardening leads to tool wear.
-
Low modulus → vibration and chatter during machining.
Solutions: Use coated carbide or CBN tools, apply cryogenic or high-pressure coolant, and adopt rigid fixturing.
PEEK
-
Thermoplastic behavior → can melt or deform with excessive heat.
-
Moisture absorption may cause dimensional instability.
-
Burr formation common in milling.
Solutions: Use sharp tools, low cutting speeds, and air cooling instead of liquid coolant to prevent swelling.
III. CNC Machining Techniques
Boona Prototypes leverages advanced machining setups for aerospace polymers and metals:
-
5-axis CNC machining for complex geometries.
-
Cryogenic cooling for titanium alloys.
-
Precision milling and turning for PEEK with tight tolerances.
-
Surface finishing services (polishing, bead blasting, anodizing, passivation).
Table 2. Recommended Machining Parameters
| Material | Tool Type | Cutting Speed (m/min) | Feed Rate (mm/rev) | Cooling Method |
|---|---|---|---|---|
| Titanium | Carbide, TiAlN-coated | 30–60 | 0.1–0.3 | High-pressure/coolant or cryogenic |
| PEEK | Sharp carbide tools | 250–500 | 0.1–0.4 | Air blast (avoid liquid) |
IV. Aerospace Applications
-
Titanium Alloys
-
Jet engine components
-
Landing gear and fasteners
-
Structural frames and skins
-
-
PEEK
-
Cable insulation, seals, and gaskets
-
Lightweight bearings and bushings
-
Cabin interior components
-
The combination of Titanium’s structural strength and PEEK’s lightweight versatility is increasingly common in hybrid aerospace designs.
V. Cost and Manufacturing Considerations
Machining costs vary depending on complexity, tool wear, and finishing requirements.
Table 3. Cost Comparison Factors
| Factor | Titanium | PEEK |
|---|---|---|
| Raw Material Price | High (~$40–60/kg) | Moderate (~$60–80/kg for pellets; ~$150/kg for rods) |
| Machining Cost Impact | High (tool wear, longer cycle times) | Moderate (thermal distortion control needed) |
| Scrap/Waste Impact | High | Low–Moderate |
Insight: While Titanium machining is expensive due to tooling and cycle time, PEEK offers cost savings for non-critical load-bearing parts.
VI. Future Trends
-
Composite PEEK (CF-PEEK, GF-PEEK): Reinforced for higher structural strength.
-
Next-generation Titanium alloys: Engineered for improved machinability.
-
Hybrid manufacturing: Combining additive manufacturing with CNC finishing.
-
AI-driven machining: Optimized toolpaths to reduce waste and improve precision.
Conclusion
Machining Titanium and PEEK requires expertise, precision, and advanced equipment. Titanium offers unmatched structural strength, while PEEK delivers lightweight, chemical-resistant versatility.
For aerospace manufacturers, partnering with specialists like Boona Prototypes ensures high-quality machining, faster lead times, and aerospace-grade reliability.
FAQs
1. Why is Titanium so difficult to machine?
Titanium has low thermal conductivity, which causes heat to build up at the cutting edge, leading to rapid tool wear. It also has a low modulus of elasticity, making it prone to vibration and chatter during machining. Specialized tooling and cooling methods are required.
2. Is PEEK a good alternative to metal in aerospace applications?
Yes. PEEK (Polyether Ether Ketone) offers excellent chemical resistance, lightweight properties, and high temperature performance (up to 250°C continuous use). While it cannot match Titanium’s structural strength, it is ideal for interior, electrical, and non-load-bearing aerospace components.
3. What are the best machining practices for Titanium alloys?
-
Use carbide or coated tools (TiAlN, CBN, PCD).
-
Maintain low cutting speeds (30–60 m/min).
-
Apply high-pressure or cryogenic cooling.
-
Ensure rigid clamping to minimize vibration.
4. How do you prevent PEEK from melting or deforming during machining?
PEEK should be machined with sharp tools, low cutting speeds, and light feed rates. Air cooling or dry machining is recommended, as liquid coolants can cause swelling. Proper fixturing prevents part distortion.
5. Which aerospace parts are commonly made from Titanium?
Titanium is used for jet engines, landing gear, fasteners, airframes, and other high-load structural components where strength and temperature resistance are critical.
6. What aerospace components are typically made from PEEK?
PEEK is commonly used for electrical connectors, seals, bearings, gaskets, cable insulation, and lightweight interior parts, especially where chemical resistance and weight savings are needed.
7. How do machining costs compare between Titanium and PEEK?
Titanium machining is generally more expensive due to tool wear, slower cutting speeds, and finishing requirements. PEEK is easier and faster to machine, but raw stock (rods, plates) can also be costly.
8. Can CNC machining be combined with additive manufacturing for these materials?
Yes. Hybrid manufacturing is an emerging trend. Titanium parts are often 3D printed (additive manufacturing) and then finished by CNC machining for precision. PEEK can also be 3D printed and post-machined for tight tolerances.
