The Best Materials for CNC Machining
When it comes to CNC machining, choosing the right material is just as important as choosing the right manufacturing process. The material you select affects everything from machining time and production costs to strength, corrosion resistance, weight, and the overall lifespan of the finished component.
Whether you’re manufacturing a one-off prototype or a high-volume production run, selecting the correct material can improve performance while reducing unnecessary costs.
At Engineered Components, we machine a wide range of metals and engineering plastics for customers across industries including oil and gas, aerospace, medical, food processing, automotive, defence, and general engineering. This guide explains the most commonly machined CNC materials, their advantages, limitations, and where each performs best.
What Makes a Material Suitable for CNC Machining?
Not every material machines equally well. Some cut cleanly at high speeds with excellent surface finishes, while others require slower machining, specialist tooling, or careful programming.
The main factors considered when selecting a CNC machining material include:
- Strength
- Weight
- Corrosion resistance
- Heat resistance
- Wear resistance
- Dimensional stability
- Machinability
- Material availability
- Cost
Balancing these factors ensures the finished part performs as intended without unnecessarily increasing manufacturing costs.
Aluminium
Aluminium is one of the most popular CNC machining materials due to its excellent balance of strength, low weight, corrosion resistance, and ease of machining.
Advantages
- Excellent machinability
- Fast machining times
- Lightweight
- Naturally corrosion resistant
- Good thermal conductivity
- Excellent surface finish
- Easily anodised
Typical Applications
- Aerospace components
- Automotive parts
- Medical equipment
- Electronics housings
- Pneumatic components
- Fixtures and jigs
Common Grades
6082
The UK’s most commonly used structural aluminium with excellent strength and good corrosion resistance.
6061
Widely used internationally with good all-round mechanical properties.
7075
A high-strength aerospace-grade aluminium with exceptional mechanical properties.
Stainless Steel
Stainless steel offers excellent corrosion resistance and mechanical strength, making it one of the most versatile engineering materials available.
Although machining takes longer than aluminium, the durability of stainless steel makes it ideal for demanding applications.
Advantages
- Excellent corrosion resistance
- High strength
- Long service life
- Hygienic
- Attractive surface finish
- Good temperature resistance
Typical Applications
- Food processing
- Pharmaceutical equipment
- Oil and gas
- Marine equipment
- Pumps
- Valves
- Medical devices
Popular Grades
303 Stainless Steel
Designed specifically for machining.
Advantages:
- Excellent machinability
- Good corrosion resistance
- Lower machining costs
Ideal for:
- Fasteners
- Shafts
- Fittings
304 Stainless Steel
The world’s most commonly used stainless steel.
Advantages:
- Excellent corrosion resistance
- Good weldability
- Strong and durable
Ideal for:
- Food equipment
- Medical equipment
- Architectural components
316 Stainless Steel
Contains molybdenum, providing superior corrosion resistance.
Advantages:
- Excellent chemical resistance
- Marine suitable
- High corrosion resistance
Ideal for:
- Offshore equipment
- Marine applications
- Chemical processing
- Pharmaceutical components
17-4 PH Stainless Steel
A precipitation-hardening stainless steel combining corrosion resistance with very high strength.
Advantages
- Extremely strong
- Good wear resistance
- Heat treatable
- Excellent dimensional stability
Applications
- Aerospace
- Defence
- Oil & gas
- Hydraulic components
- High-pressure equipment
Mild Steel
Mild steel remains one of the most economical materials for CNC machining.
Advantages
- Low material cost
- Easy to machine
- Strong
- Readily available
Applications include:
- Machinery
- General engineering
- Fabrications
- Mounting brackets
- Fixtures
Common grades include:
- EN3B
- EN1A
- EN8
- EN24
Tool Steel
Tool steels are selected where hardness and wear resistance are critical.
Advantages include:
- Exceptional hardness
- Excellent wear resistance
- Long service life
Applications include:
- Mould tools
- Dies
- Punches
- Cutting tools
- Production tooling
Titanium
Titanium offers one of the highest strength-to-weight ratios of any engineering metal.
Although expensive and slower to machine, it provides exceptional performance.
Advantages
- Lightweight
- Extremely strong
- Excellent corrosion resistance
- Biocompatible
Applications
- Aerospace
- Medical implants
- Motorsport
- Defence
- Marine
Brass
Brass is among the easiest engineering materials to machine.
Advantages
- Outstanding machinability
- Attractive finish
- Corrosion resistant
- Excellent electrical conductivity
Applications
- Hydraulic fittings
- Pneumatic fittings
- Electrical connectors
- Decorative components
- Instrumentation
Copper
Copper is selected primarily for its conductivity.
Advantages
- Excellent electrical conductivity
- Excellent thermal conductivity
- Corrosion resistant
Applications
- Busbars
- Electrical contacts
- Heat exchangers
- Cooling systems
Bronze
Bronze alloys offer exceptional wear resistance.
Advantages
- Excellent bearing properties
- Low friction
- Good corrosion resistance
Applications
- Bearings
- Bushes
- Marine components
- Wear plates
Common grades include:
- Phosphor Bronze
- Aluminium Bronze
- Gunmetal
Engineering Plastics
Engineering plastics have become increasingly popular due to their low weight, chemical resistance, and ease of machining.
Acetal (Delrin®)
Advantages
- Excellent dimensional stability
- Low friction
- Easy machining
- Moisture resistant
Applications
- Rollers
- Bearings
- Gears
- Wear strips
Nylon
Advantages
- Tough
- Wear resistant
- Low friction
Applications
- Bushes
- Rollers
- Guide rails
- Pulleys
PTFE (Teflon®)
Advantages
- Outstanding chemical resistance
- Very low friction
- High temperature resistance
Applications
- Seals
- Valve seats
- Bearings
- Chemical equipment
PEEK
PEEK is one of the highest-performance engineering plastics available.
Advantages
- Extremely strong
- High temperature capability
- Chemical resistant
- Excellent wear resistance
Applications
- Aerospace
- Medical
- Semiconductor
- Oil & gas
- Electrical insulation
Material Comparison
| Material | Machinability | Strength | Corrosion Resistance | Relative Cost |
|---|---|---|---|---|
| Aluminium | Excellent | Medium | Excellent | £ |
| Mild Steel | Excellent | High | Poor | £ |
| 303 Stainless | Excellent | High | Good | ££ |
| 304 Stainless | Good | High | Excellent | ££ |
| 316 Stainless | Moderate | High | Outstanding | £££ |
| 17-4 PH | Moderate | Very High | Excellent | £££ |
| Brass | Outstanding | Medium | Excellent | ££ |
| Bronze | Good | High | Excellent | £££ |
| Titanium | Difficult | Very High | Outstanding | ££££ |
| Acetal | Excellent | Medium | Excellent | ££ |
| Nylon | Good | Medium | Excellent | ££ |
| PEEK | Moderate | High | Excellent | ££££ |
Which Material Is Right for Your Project?
There is no universal “best” material for CNC machining. The ideal choice depends on the application’s requirements, including:
- Mechanical strength
- Operating temperature
- Chemical exposure
- Weight restrictions
- Wear resistance
- Required tolerances
- Surface finish
- Production volume
- Budget
For example, aluminium is ideal when weight and cost are priorities, while stainless steel is better suited to corrosive environments. PEEK excels in demanding high-temperature applications, and brass offers excellent machinability for precision fittings.
An experienced machining partner can help balance performance, manufacturability, and cost to recommend the most suitable material for your project.
Why Material Selection Matters
Material selection has a significant impact on machining efficiency, lead times, and overall project costs. A material that is stronger than necessary may increase machining time and tooling wear, while a material that is too soft or lacks corrosion resistance may lead to premature failure in service.
By selecting the most appropriate material from the outset, manufacturers can achieve better performance, improved reliability, and lower lifetime costs.
At Engineered Components, we work closely with customers to identify the optimum material for every application, ensuring components meet performance requirements while remaining cost-effective to manufacture.
Frequently Asked Questions
What is the easiest material to CNC machine?
Brass and aluminium are generally considered the easiest materials to machine due to their excellent machinability and ability to produce high-quality surface finishes.
What is the strongest material commonly CNC machined?
17-4 PH stainless steel, tool steels, and titanium are among the strongest materials regularly machined, depending on the application’s requirements.
Which material is best for corrosion resistance?
316 stainless steel provides excellent corrosion resistance for most industrial environments, while titanium offers exceptional resistance in highly aggressive conditions.
Can plastics be CNC machined?
Yes. Engineering plastics such as Acetal (Delrin®), Nylon, PTFE, and PEEK are widely CNC machined for applications requiring low weight, chemical resistance, electrical insulation, or low friction.
Does the material affect machining cost?
Absolutely. Material hardness, machinability, tooling wear, machining time, and raw material cost all contribute to the overall cost of CNC machining.