What is Aircraft Grade Aluminum? Complete Guide to Aerospace Alloys

Aircraft aluminum grades vary, offering capabilities ranging from superior fatigue resistance and thick-plate corrosion resistance to ultra-high structural strength. For different aviation aluminum components and operating conditions, selecting the right aerospace aluminum grade is critical. Simultaneously, these aluminum alloys used in aircraft (2014, 2024, 6061, 7050, 7075, 7068) exhibit different levels of machinability during CNC machining or secondary processing. This article covers the key properties, applications, and manufacturing considerations for these aircraft aluminum parts, while providing practical tips for machining, cost reduction, and design optimization. At the end, we will also share a case study of how we solved the warp and the micro-gaps along the sealing joint issues for a client’s drone aluminum EMI enclosures.

What Is Aircraft Grade Aluminum？Key Pros and Uses

This is a very easy concept to understand that some high-performance aluminum alloy grades are widely favored for aircraft parts and UAV (drone) components due to their lightweight nature (essential for aerospace weight reduction) combined with high strength, fatigue resistance, and stress corrosion resistance.

The most common aircraft aluminum grades include 2014, 2024, 6061, 7050, 7075, and 7068. Below, they are listed in order of popularity, highlighting their core aerospace advantages and typical applications (large components are typically produced via die forging or extrusion with assembly, while smaller are usually CNC machined aluminum parts ):

7075 Aircraft Aluminum (Ultra-High Structural Strength): Primary wing spars, landing gear components, and fuselage structural frames; control rod joints, rocker arms, small latches, high-load support brackets, and critical hinge pins.

7050 (Highest Stress Corrosion Resistance in Thick Sections): Large fuselage frames and thick-plate structural components; small frame connectors machined directly from thick plates, internal thick-walled angle fittings, etc.

2024 (Best Fatigue Strength): Fuselage skins, lower wing surfaces, and primary load-bearing structures; attachment fittings subject to cyclic tension or vibration, hinges, fuselage reinforcing plates, and high-tensile structural rivets.

6061 (Good All-Around Performance, Easy to Weld): Precision 6061 CNC machined parts, such as instrument panel mounts, air conditioning duct clamps, and cabin interior brackets.

7068 (High Tensile Strength, High Load Capacity): Heavy-duty lugs and pivot pins at wing-to-fuselage joints, landing gear actuator rocker arms; aerospace hydraulic valve blocks, high-pressure pistons, etc.

2014 (Forged High-Hardness Aluminum): Mostly large/heavy aircraft forgings, wheel hubs, and load-bearing connection members; high-stress anti-collision fittings, small heavy-load brake forgings, small wheel assemblies, and high-strength retaining rings.

Key Properties Comparison for Aircraft Grade Aluminum

The following matrix compares these aircraft aluminum grades across core physical mechanical properties, corrosion resistance, machinability ratings, and cost factors:

(“T “ means temper, that the aluminum can be strengthened by heat treatment)

How to Control Deformation and Manage Tolerance for Aircraft Aluminum Machined Parts

Precision small-to-medium aluminum parts for aircraft, drones, or satellite applications are typically made using precision CNC machining. In this process, computer-controlled tools of various shapes and sizes cut a solid aluminum block along specific paths to shape the part. If tighter tolerances (such as ±0.005 mm) are required, further precision grinding is needed to achieve better accuracy and surface quality, which incurs extra costs.

Tips for Managing Tolerances for Cost Optimization

• Precision Fit Areas (±0.005 mm to ±0.01 mm): Limit tight tolerances strictly to functional mating features, like bearing seats and locating pin holes.

• Screw & Mounting Holes (±0.05 mm to ±0.1 mm): Apply moderate tolerances to custom screw placement and mounting holes. Clearance holes naturally provide enough play for smooth custom assembly.

• Internal Cutouts & Open Spaces (±0.1 mm to ±0.2 mm): Use looser tolerances for hollowed-out pockets, corner radii, and open clearance cuts that do not touch other components.

• Non-Critical Outer Dimensions (±0.2 mm to ±0.5 mm):Allow loose tolerances on non-mating overall length, width, and height to largely save production cost.

Additionally, during CNC machining, high-strength aerospace aluminum alloys often contain high internal residual stress. Material removal releases this stress, causing thin-walled or asymmetric parts to deform, warp, or twist.

Tips for Controlling Deformation (Design Tips):

Maintain Minimum Wall Thickness & Aspect Ratios:

• Keep minimum wall and floor thickness at ≥ 1.5 mm for 7075-T6 and 2024-T3 alloys.

• Limit the unsupported wall height-to-thickness ratio to a maximum of 10:1 (e.g., a 15 mm tall thin wall must be at least 1.5 mm thick) to prevent chatter, cutter deflection, and wall bowing during stock removal.

• Avoid sharp transitions from thick bosses to thin webs; add a transition fillet radius (R ≥ 2 mm) or a gradual 3:1 taper to distribute stress evenly.

Symmetric Cross-Sections & Pocket Placement:

• Dual-Sided Pocketing: Design deep light-weighting pockets symmetrically on both top and bottom faces relative to the part’s neutral axis, rather than milling out 80% of material from a single side.

• Balanced Structural Ribs: Position stiffening ribs symmetrically around the part centerline. Balanced geometric features ensure that internal residual stress in the aluminum block releases equally from both sides, preventing post-machining twisting or bowing.

Choose Surface Treatments for Aircraft Aluminum Components

Choosing the right surface treatment for aerospace aluminum depends on the operating environment, conductivity requirements, wear exposure, and target budget.

Aerospace Surface Treatment Selection Table

VMT CNC Prototyping Machining Fatcory Case Study

A UAV client came to us with a 6061-T6 aluminum EMI enclosure that failed RF sealing tests when produced by a previous supplier. The part featured a 1.2 mm thin wall and a 200 mm tongue-and-groove mating flange requiring ±0.01 mm flatness.

Our engineering team analyzed and told client that the primary reason is the material stress and improper machining (like, machined the main pocket in a single heavy pass from one side, which released internal material stresses and built up heat, causing the thin flange to warp slightly and create micro-gaps along the sealing joint).

We switched the stock to pre-stretched 6061-T651 aluminum to reduce base material stress, and then split the CNC process into distinct roughing and finishing stages: first, we rough-milled the pocket and outer profile symmetrically from both sides, leaving 0.5 mm of stock, and allowed the part to rest for 24 hours to relieve residual stresses. For final finishing, we replaced standard mechanical vise clamps with a custom vacuum fixture to avoid clamping distortion, using sharp, high-helix carbide tools with light cut depths to keep cutting forces and heat low.

To ensure proper electrical conductivity across the joint, we treated the part with MIL-DTL-5541 Class 3 trivalent chromate conversion (Chem Film) rather than anodizing, which would have formed an insulating layer. The chemical film offered reliable corrosion protection while maintaining low surface electrical resistance for EMI shielding.

With the final flange flatness held consistently within 0.008 mm, the custom enclosure passed all RF leakage tests on the first attempt. The clients were satisfied with these aluminum EMI enclosures for their drones and willing to keep in touch with us in the future.

Final Thoughts

Selecting the ideal aerospace aluminum alloy requires a balance between performance requirements, design symmetry, and manufacturing economics. While high-strength options like 7075 and 7068 excel in ultra-high load applications, versatile alloys like 6061-T6 provide exceptional value for less critical structural components and aesthetic parts. In addition, 7050 for high SCC to thick components safety while 2024 for excellent fatigue resistance, and 2014 for high forgings with high hardness. Ultimately, achieving a high-performance, cost-effective aerospace component goes beyond material selection. By applying selective tight tolerances, implementing stress-relieving design practices, and selecting the appropriate functional surface treatment, your team can surely reduce deformation risks and unnecessary machining costs. Still troubled by tolerances, design and cost optimization for aircraft aluminum alloy components? Welcome to contact us to get a free DFM review and quick quote within 24 hours. [2D Drawings (PDF files), 3D Drawings (IGS/STP/STEP files)].