CNC machining is one of the most versatile and precise manufacturing methods available today.
It enables the production of complex parts with tight tolerances and excellent surface finishes. While CNC machines can handle a variety of materials, metals remain the backbone of most industrial applications due to their strength, durability, and thermal stability.

This guide highlights the top five metals used in CNC machining, explaining their unique characteristics and where they’re most effectively applied. Whether you're prototyping or producing in volume, choosing the right metal is crucial to part performance, cost-efficiency, and manufacturability.

1. Aluminum: Lightweight Versatility

Aluminum is the most commonly used metal in CNC machining due to its excellent machinability and lightweight properties.

Key Characteristics:

• Low density (2.7 g/cm³)

• High strength-to-weight ratio

• Corrosion-resistant (especially with anodizing)

• Excellent thermal and electrical conductivity

• Cost-effective and widely available

Common Alloys:

• 6061: General-purpose; great for structural parts

• 7075: High-strength alloy used in aerospace

• 2024: Offers high fatigue resistance

Applications:

• Aerospace frames and brackets

• Automotive engine components

• Consumer electronics housings

• Medical device enclosures

• Robotics and automation parts

Aluminum’s balance of strength and machinability makes it ideal for parts requiring both performance and manufacturability. It’s also easy to anodize for added surface protection and color coding.

2. Stainless Steel: Corrosion Resistance & Strength

Stainless steel is known for its excellent strength and corrosion resistance, especially in harsh environments.
It’s used widely in industries that require durability, hygiene, and structural integrity.

Key Characteristics:

• High tensile strength

• Excellent resistance to rust and chemicals

• Can withstand sterilization and extreme temperatures

• Non-reactive, making it ideal for food-grade and medical applications

Common Grades:

• 304: General-purpose stainless with good formability

• 316: Higher corrosion resistance, especially in saline environments

• 17-4 PH: Precipitation-hardened for extra strength and wear resistance

Applications:

• Surgical tools and medical implants

• Food processing equipment

• Industrial fasteners

• Marine hardware

• Chemical tanks and valves

Stainless steel is more challenging to machine than aluminum due to its hardness and work hardening properties. However, experienced CNC machining service providers use the right tooling and coolant strategies to ensure high-quality finishes.

3. Brass: Excellent Machinability and Appearance

Brass is a copper-zinc alloy prized for its ease of machining, acoustic properties, and attractive appearance.
It is often chosen when aesthetic finish and tight tolerances are essential.

Key Characteristics:

• Outstanding machinability

• Low friction and excellent wear resistance

• Naturally antimicrobial

• Visually appealing (gold-like color)

• Good electrical conductivity

Common Grades:

• C360 (Free-Cutting Brass): Highly machinable and ideal for high-volume production

• C260 (Cartridge Brass): Better formability, used for bending and drawing

Applications:

• Electrical connectors and terminals

• Valve and pump components

• Decorative hardware

• Musical instruments

• Plumbing fittings

Brass offers the added advantage of reduced tool wear, making it ideal for precision machining in large quantities.

4. Titanium: High Strength and Biocompatibility

Titanium is a high-performance metal used in critical applications where strength, weight savings, and corrosion resistance are vital.
Though expensive and harder to machine, it’s unmatched in performance for demanding sectors.

Key Characteristics:

• High strength-to-weight ratio

• Excellent corrosion resistance (even in seawater and bodily fluids)

• Biocompatible and non-toxic

• Non-magnetic and non-reactive

• Low thermal conductivity

Common Grades:

• Grade 2: Commercially pure titanium, easier to machine

• Grade 5 (Ti-6Al-4V): Aerospace-grade, high strength and heat resistance

Applications:

• Aerospace structural components

• Medical implants and surgical tools

• Military and defense hardware

• High-performance automotive parts

• Chemical processing equipment

Titanium machining requires specialized tools, slower feed rates, and controlled heat management, but the resulting parts offer unparalleled performance.

5. Steel (Carbon & Alloy): Durability and Cost Efficiency

Carbon steel and alloy steel are staples in industrial CNC machining for parts that need strength, toughness, and wear resistance.
They are more affordable than stainless steel and offer excellent mechanical properties.

Key Characteristics:

• High hardness and impact resistance

• Cost-effective for structural applications

• Easily heat-treated for improved strength and wear properties

• Can be surface-hardened or coated for corrosion protection

Common Grades:

• 1018 (Low Carbon Steel): Easily machined, suitable for general-purpose parts

• 4140 (Alloy Steel): High-strength and wear-resistant

• 1045 (Medium Carbon Steel): Balanced hardness and machinability

Applications:

• Shafts, gears, and couplings

• Tooling components

• Heavy machinery and construction equipment

• Automotive axles and frames

• Industrial rollers and dies

While steel is harder on tools than aluminum or brass, it’s a top choice for parts that require long-term durability under mechanical stress.

Choosing the Right Metal for CNC Machining

Selecting the right metal depends on the following:

• Application Requirements: Does the part need to be lightweight, corrosion-resistant, or able to withstand high loads?

• Machinability: How easily can the metal be shaped, and what tooling is required?

• Cost: Is the project budget-sensitive, or is material performance the top priority?

• Post-Processing Needs: Will the part be anodized, coated, or heat-treated?

• Regulatory Standards: Medical and aerospace applications require specific certifications and traceability.

A knowledgeable CNC machining partner can help evaluate these variables and recommend the optimal material based on your design and performance goals.

Summary Table: Top 5 CNC Metals at a Glance

Final Thoughts

The choice of metal in CNC machining has a direct impact on performance, cost, and product success.
Each metal brings unique mechanical and chemical properties, and choosing the right one requires a balance between function, budget, and manufacturability.

Whether you’re developing a prototype or running a high-volume part order, partnering with an experienced CNC machining service ensures that your material selection, toolpath strategy, and surface finish align perfectly with your project’s goals.