Choosing the right material is a critical first step in CNC machining. The material you select not only affects the final product’s performance and durability, but also impacts machining time, cost, and how well the part performs in its intended environment. In this guide, we’ll walk you through key types of materials used in CNC machining, their main characteristics, common applications, and how to choose the most suitable option for your project.

Why Material Selection Matters？

1. It Determines Part Performance

The material defines how your part behaves in real use:

• Strength (can it withstand load?)

• Hardness (wear resistance)

• Corrosion resistance

• Heat resistance

Example: Aluminum is lightweight and good for housings, while stainless steel is better for harsh environments.

2. It Impacts Cost

Material choice affects:

• Raw material price

• Machining time

• Tool wear

Example:

• Aluminum → cheap + fast machining

• Titanium → expensive + slow machining

So choosing the wrong material can double your cost.

3. It Affects Machinability

Some materials are easy to machine, others are not:

• Easy: aluminum, brass

• Difficult: stainless steel, titanium

Harder materials mean:

• Slower production

• Higher tooling cost

• More risk of defects

4. It Must Match the Working Environment

Your part may face:

• High temperature

• Moisture

• Chemicals

• Friction

Example:

• Outdoor parts → need corrosion resistance

• Moving parts → need wear resistance

Wrong material = early failure.

5. It Affects Precision & Tolerances

Different materials behave differently during machining:

• Thermal expansion

• Deformation

• Surface finish quality

 Some plastics may deform, while metals hold tighter tolerances.

6. It Influences Production Efficiency

Material affects:

• Cutting speed

• Tool life

• Scrap rate

Good material choice =

•  faster production
• stable quality
•  lower defect rate 

Characteristics of Different Metal Materials and Their Applications in CNC Machining

• Aluminum

Aluminum is a silvery-white metal known for its lightweight nature, excellent corrosion resistance, and outstanding electrical and thermal conductivity. Easy to machine and infinitely recyclable, it has become one of the most versatile materials in modern manufacturing. Its unique combination of strength and low weight supports industries striving for higher efficiency and energy savings, while its natural resistance to corrosion ensures long-term durability across a wide range of applications—from construction and transportation to advanced electronics. In addition, aluminum offers exceptional value in sustainability: recycled aluminum retains its core properties and significantly reduces production costs and environmental impact, making it one of the most cost-effective and eco-friendly materials in today’s manufacturing landscape. Making recycled aluminum only takes around 5% of the energy needed to make new aluminum — reducing carbon emissions and saving money for businesses and end consumers.

Although aluminum is widely used in CNC machining due to its lightweight and excellent machinability, it also has several limitations that should be considered when selecting materials.

One of the main disadvantages of aluminum is its lower strength compared to steel. While certain alloys like 7075 offer higher strength, most common grades such as 6061 are not suitable for applications requiring extremely high load-bearing capacity. In addition, aluminum has relatively low hardness, which makes it more prone to surface scratches, wear, and deformation under heavy mechanical stress.

Another limitation is its poor high-temperature resistance. Aluminum tends to lose strength when exposed to elevated temperatures, making it less ideal for components used in high-heat environments. Furthermore, although aluminum has good corrosion resistance, it can still be affected by galvanic corrosion when in contact with other metals, especially in humid or marine conditions.

Overview of Aluminum Properties 

• Lightweight: Density of ~2.7 g/cm³, about one-third of steel
• High strength-to-weight ratio: Especially in alloys like 6061 and 7075
• Excellent corrosion resistance: Natural oxide layer protects against rust
• Good electrical conductivity: ~61% of copper
• High thermal conductivity: ~205 W/m·K, ideal for heat dissipation
• Excellent machinability: Suitable for CNC machining and mass production
• Infinitely recyclable: Retains properties with up to 95% energy savings

Disadavantages

• Lower strength than steel in heavy-load applications
• Relatively soft: prone to scratches, wear, and deformation
• Poor high-temperature resistance: loses strength under heat
• Galvanic corrosion risk when in contact with dissimilar metals
• Higher material cost than some steels (in certain markets)

Best Applications of Aluminum

• Aerospace – aircraft structures, frames
• Automotive – lightweight parts, EV components
• CNC Machining – precision parts, housings
• Electronics – heat sinks, enclosures
• Construction – windows, facades, roofing
• Power Transmission – electrical cables and conductors

When NOT to Use Aluminum

• Heavy load-bearing structures → steel is a better choice
• High-temperature environments → risk of strength loss
• High-wear applications → insufficient hardness
• Strong impact or fatigue conditions
• Galvanic environments without protection (marine + mixed metals)

• Stainless Steel

Stainless steel is a key material in CNC machining, valued for its outstanding corrosion resistance, high strength, and long service life. 

The term “stainless steel” refers to a broad family of corrosion-resistant alloys, typically containing a minimum of around 11% chromium，which reacts with oxygen to form a thin, protective oxide film on the surface, preventing rust and environmental damage.. By adjusting the chromium level and incorporating additional elements such as nickel, molybdenum, titanium, and niobium, manufacturers can significantly modify the material’s mechanical strength, durability, and chemical resistance.

As a result, stainless steel is available in hundreds of different grades, each designed to meet specific industrial requirements and standardized under various international systems. These grades are further classified into five main categories based on their metallurgical microstructure: austenitic, ferritic, martensitic, duplex, and precipitation hardening stainless steels.

Lex Hardware lists below the most suitable stainless steel materials for CNC machining, along with material references from AZoM, and provides a comparison of the advantages and disadvantages of stainless steel in machining.

Suitable stainless steel materials for CNC machining

Grade	Machinability	Key Characteristics	Typical Applications
303 Austenitic stainless steel	Good	Sulfur-added free-machining stainless steel; excellent chip breaking; slightly reduced corrosion resistance vs 304	Screws, fasteners, precision shafts, fittings
304 Austenitic stainless steel	Fair	Most common stainless steel; excellent corrosion resistance; prone to work hardening	Food equipment, tanks, architectural parts
316 / 316L Austenitic stainless steel	Poor	Molybdenum-added for superior corrosion resistance; excellent for marine and chemical environments	Marine components, medical devices, chemical equipment
416 Martensitic stainless steel	Excellent	Free-machining stainless steel with high sulfur content; very good machinability but lower corrosion resistance	Shafts, gears, valves, pump components
17-4 PH Precipitation Hardening stainless steel	Fair	High strength, heat treatable, good corrosion resistance, widely used in aerospace	Aerospace parts, high-strength structural components

comparison of the advantages and disadvantages of stainless steel in machining.

• Copper

Copper is a cornerstone of precision manufacturing. Its unique combination of excellent thermal conductivity, corrosion resistance, and high ductility makes it an ideal engineering metal. However, its soft and ductile nature can present challenges in CNC machining, such as chip evacuation problems and increased tool wear. Nevertheless, these very properties render copper indispensable for electrical components, heat sinks, and diverse industrial applications.

• Conclusions

Dimension	Aluminum Alloys	Stainless Steel	Copper Alloys
1. Common Grades	6061-T6: General Structural 7075-T6: Aerospace High-Strength 5052: Sheet Metal Forming	304 / 304L: General Corrosion Resistant 316 / 316L: Medical/Marine Grade 17-4 PH: Precipitation Hardening	C36000: Free-Cutting Brass C11000: ETP Copper (High Conductivity) C17200: Beryllium Copper (High Strength/Spring)
2. Key Advantages	Excellent Machinability: High cutting speeds, long tool life. Lightweight: Low density (~2.7 g/cm³). Cost-Effective: Low raw material cost, versatile finishing.	High Strength & Hardness: Wear-resistant, structurally robust. Superior Corrosion Resistance: Ideal for harsh environments. Heat Resistance: Suitable for high-temperature applications.	Top-Tier Conductivity: Best for electrical & thermal apps. Antimicrobial: Ideal for medical/hygiene uses. Non-Magnetic: Critical for specific electronic environments.
4. Primary Applications	Consumer Electronics Housings Automotive Lightweight Structures Drone/Aerospace Brackets Robotics Arms	Medical Devices & Surgical Tools Marine Engineering Components Food Processing Equipment Oil & Gas Valves	Electrical Connectors & Busbars Heat Sinks & Heat Exchangers Musical Instruments & Decor Explosion-Proof Tools (BeCu)
6. Machining Labor Cost	Lowest Extremely high Material Removal Rate (MRR). Short cycle times. Ideal for high volumes.	High Low Surface Feet per Minute (SFM). Frequent tool changes. Cycle times can be 3-4x longer than Aluminum.	Variable C36000 (Brass): Very fast (cost comparable to Aluminum). C11000 (Pure Cu): Slow due to reduced speeds to prevent BUE; high labor cost.
7. Post-Processing Cost	Medium Often requires Anodizing, bead blasting, or brushing. Adds process steps.	Low Usually only needs Passivation or polishing. No coating required for rust protection.	Medium Often requires Nickel/Tin plating to prevent oxidation. Chemical polishing common. High packaging care needed.
8. Total Budget Verdict	Best Value King Ideal for: Weight-sensitive parts, non-critical strength, high-volume budgets.	Performance First Ideal for: High-strength, corrosion-resistant, high-temp critical structural parts.	Function Critical Ideal for: Parts where conductivity, thermal dissipation, or antimicrobial properties are mandatory.

Our material selection guide and cost estimates are based on current market data from the London Metal Exchange (LME) and technical machining parameters defined by ASM International and leading tooling manufacturers like Sandvik Coromant. The 2026 price projections align with supply-demand forecasts from the International Copper Association and BloombergNEF regarding the EV and AI infrastructure boom.

Reference Sources

• ASM International (American Society for Materials)

ASM Handbook, Vol. 2: Properties and Selection: Nonferrous Alloys and Special-Purpose Materials 及 Vol. 16: Machining.

• NIST (National Institute of Standards and Technology)
•  International Copper Association (ICA)