Aluminum is one of the most commonly used metals in CNC machining due to its excellent machinability, strength-to-weight ratio, and versatility across industries. From aerospace to automotive, electronics to consumer products, aluminum components offer performance, affordability, and reliability.
However, not all aluminum grades are the same. Each alloy offers unique properties that affect strength, corrosion resistance, thermal conductivity, and machinability. Choosing the right aluminum grade for CNC machining is essential to ensure part performance, cost efficiency, and manufacturability.
This guide breaks down the most common aluminum grades for CNC machining, their properties, applications, and selection criteria.
Why Aluminum Is a Top Choice for CNC Machining Before we explore the grades, it's important to understand why aluminum is so widely used in CNC operations:
🔩 High machinability — Clean chip formation and low tool wear
⚖️ Lightweight — Ideal for reducing component mass without compromising strength
🧊 Thermal conductivity — Effective for heatsinks and enclosures
🌧️ Corrosion resistance — Useful for outdoor or moisture-prone applications
🔧 Anodizing compatibility — Supports cosmetic and protective surface treatments
💰 Cost-effective — Readily available and affordable for prototyping and production
These features make aluminum an ideal candidate for everything from rapid prototyping to mass production of custom parts.
Major Aluminum Grades Used in CNC Machining Aluminum alloys are typically categorized into two types: wrought alloys (worked into shape) and cast alloys (poured into molds). CNC machining almost exclusively uses wrought grades due to their better formability and mechanical consistency.
Here are the most common aluminum grades used in CNC machining.
Key Features: Good strength-to-weight ratio
Excellent corrosion resistance
Great for welding and anodizing
Widely available and affordable
Applications: Aerospace components
Consumer electronics
Bicycle frames and automotive parts
Housings and structural enclosures
Why it's popular: 6061 is a general-purpose alloy that’s easy to machine and meets a wide range of design requirements without added cost.
Key Features: High tensile strength (similar to steel)
Moderate corrosion resistance
Limited weldability
Anodizes well, though less consistently than 6061
Applications: Aircraft wing structures
Defense-grade brackets
High-performance sporting goods
Aerospace tooling and fixtures
Why it’s used: When you need strength and stress resistance without added weight, 7075 is the go-to alloy—even though it's more expensive and harder to machine than 6061.
Key Features: High strength and fatigue resistance
Poor corrosion resistance (often cladded)
Excellent shear strength
Not suitable for welding
Applications: Aerospace bulkheads and skins
Structural aircraft components
Load-bearing parts under dynamic stress
Note: Parts made from 2024 often need protective coatings or anodizing to prevent corrosion.
Key Features: Outstanding corrosion resistance (marine-grade)
High formability
Lower strength than 6061 or 7075
Great for bending and sheet fabrication
Applications: Marine equipment
Chemical tanks and containers
Brackets, panels, and enclosures
Electrical enclosures exposed to moisture
Why it’s useful: 5052 is perfect for components where environmental durability is more important than high tensile strength.
Key Features: Exceptional stability for precision machining
Pre-machined flat surfaces
Excellent for fixturing and jigs
Not suitable for structural use
Applications: Tooling fixtures
Precision machining bases
Inspection equipment
Mold bases (including plastic injection molding dies)
Why machinists love it: MIC-6 saves hours of surface prep and minimizes material distortion under load—critical for jigs and fixtures.
Comparison Table of Aluminum Grades Grade Strength Corrosion Resistance Machinability Weldability Best Use Case 6061-T6 Medium High Excellent Excellent General-purpose structural 7075-T6 Very High Moderate Moderate Poor Aerospace, high-stress parts 2024-T4 High Low Good Poor Fatigue-critical applications 5052-H32 Medium Excellent Fair Good Marine, moisture-exposed use MIC-6 Low Good Excellent N/A Fixtures, tooling plates
How to Choose the Right Grade for Your CNC Project When selecting an aluminum grade for CNC machining, consider the following factors:
Strength Requirements
Use 7075 or 2024 for high-load or fatigue-prone parts
Use 6061 for balanced performance
Corrosion Exposure
Use 5052 or anodized 6061 for marine or outdoor environments
Machining Tolerance and Flatness
Choose MIC-6 for stable, precision fixtures
Budget Constraints
6061 is cost-effective for most prototypes and production parts
Post-Processing Needs
Choose grades compatible with anodizing or coating for surface protection
Applications Across Industries Industry Common Parts Recommended Aluminum Grades Aerospace Brackets, panels, housings 7075, 2024, 6061 Automotive Engine parts, chassis components 6061, 7075 Medical Devices Fixtures, enclosures, non-implant parts 6061, MIC-6 Marine Equipment Panels, mounts, sealed housings 5052, 6061 Tooling & Molds Base plates, jigs, inspection tools MIC-6
Final Thoughts Aluminum offers a unique combination of machinability, strength, and cost-efficiency for CNC machining. But choosing the right grade is essential to ensure optimal part performance, durability, and value.
For general use: go with 6061-T6
For high-stress applications: choose 7075-T6 or 2024-T4
For marine and corrosion-sensitive parts: select 5052-H32
For precision fixtures: use MIC-6
By understanding the differences between aluminum alloys, engineers and machinists can select the most suitable material for prototyping, production, or tooling applications.
Need help selecting the right aluminum alloy for your CNC project or mold base? Whether you're machining a prototype or building a fixture for plastic injection molding, material selection can make or break your project success.