Choosing the right aluminum alloy is critical for achieving optimal performance, machinability, and cost-effectiveness in CNC machined components. This technical guide compares the most commonly specified aluminum alloys and their ideal applications.

Alloy Comparison

6061-T6 (The Workhorse)

• Tensile strength: 310 MPa, yield 276 MPa
• Machinability: Excellent — good chip formation, minimal tool wear
• Weldability: Excellent — retains 60% strength in HAZ after re-aging
• Best for: Structural brackets, housings, jigs, fixtures, general machined components
• Cost index: 1.0× (baseline)

7075-T6 (The Strong One)

• Tensile strength: 572 MPa, yield 503 MPa
• Machinability: Very good — requires sharp tools and rigid setups
• Weldability: Poor — not recommended for welded assemblies
• Best for: Aerospace structures, high-stress components, lightweight alternatives to steel
• Cost index: 1.8× (vs. 6061)

2024-T3 (The Fatigue Resistant)

• Tensile strength: 483 MPa, yield 345 MPa
• Machinability: Good — slightly abrasive, use carbide tooling
• Weldability: Poor — typically riveted or mechanically fastened
• Best for: Aircraft skin, fatigue-critical structural members, fuselage components
• Cost index: 1.5× (vs. 6061)

Selection Decision Matrix

DFM Tips

• Specify 6061-T6 as default unless specific properties require alternatives
• For 7075, design for minimum 2mm wall thickness to avoid distortion during machining
• Request T6 temper for maximum strength; T651 for stress-relieved plate to minimize warping
• Consider anodizing compatibility early — 2024 produces inconsistent color in decorative anodize