CNC Machining Material Comparison
Aluminum, steel, brass, POM, PMMA, wood: which material to machine for your project?
Get a free quoteThe choice of material in CNC machining determines the strength, weight, cost and finish of your parts. From metals like aluminum and steel to engineering plastics like POM, each material has its area of excellence. Here's a comprehensive comparison.
Properties comparison
| Aluminum 6061 | Steel S235 | Brass CuZn39 | POM (Delrin) | PMMA (Acrylic) | Wood (beech) | |
|---|---|---|---|---|---|---|
| Density (g/cm³) | 2.7 | 7.85 | 8.5 | 1.41 | 1.18 | 0.6–0.9 |
| Tensile strength | 310 MPa | 400–550 MPa | 350 MPa | 65 MPa | 70 MPa | 30–50 MPa |
| Hardness | 95 HB | 120–200 HB | 100–150 HB | M80 Rockwell | M85–105 | Variable |
| Machinability | Excellent | Good | Excellent | Excellent | Good | Good |
| Corrosion resistance | Good (anodizable) | Low (rusts) | Good | Excellent | Good | Low |
| Available finishes | Anodizing, brushed, polished | Zinc plating, painting, bluing | Mirror polish, nickel plating | Raw, polished | Polished, clear, tinted | Varnish, oil, stain |
| Indicative price | €€ | € | €€€ | €€ | € | € |
Detailed material sheets
Aluminum 6061
The most commonly used aluminum in CNC machining. Lightweight, easy to machine and corrosion-resistant, it offers an excellent compromise for a wide range of applications.
Advantages
- Very lightweight (2.7 g/cm³, 3x lighter than steel)
- Excellent machinability (high cutting speeds)
- Corrosion resistant (+ anodizing option)
- Good strength-to-weight ratio
Disadvantages
- Less strong than steel for heavily loaded parts
- Scratches more easily than steel
- Limited weldability (depending on alloy)
Typical use cases
- Electronic enclosures and chassis
- Aerospace parts and drones
- Lightweight brackets and fixtures
- Metal functional prototypes
Steel S235 (structural steel)
Basic carbon steel, affordable and strong. Ideal for robust mechanical parts that will be painted or coated for corrosion protection.
Advantages
- Very high mechanical strength
- The most affordable metal to machine
- Easily weldable
- Wide availability of raw stock
Disadvantages
- Heavy (7.85 g/cm³)
- Rusts without surface treatment
- Average machinability (faster tool wear)
Typical use cases
- Structural mechanical parts
- Industrial tooling
- Heavy-duty fixtures and brackets
- Machine components
Brass CuZn39Pb3
A copper-zinc alloy, brass is a noble material that machines perfectly. It offers a characteristic golden appearance and excellent properties for precision parts.
Advantages
- Exceptional machinability (best among common metals)
- Aesthetic golden appearance, mirror polish possible
- Good electrical and thermal conductivity
- Corrosion resistant
Disadvantages
- Expensive (3x the price of aluminum)
- Heavy (8.5 g/cm³)
- Lower mechanical strength than steel
Typical use cases
- Electrical connectors and terminals
- Plumbing fittings and valves
- Decorative parts and watchmaking
- Measurement and precision instruments
POM / Delrin (Polyoxymethylene)
The quintessential engineering plastic for machining. POM offers excellent rigidity, low friction and superior chemical resistance. Ideal for precise mechanical parts.
Advantages
- Excellent friction coefficient (self-lubricating)
- Very good dimensional stability
- Chemical and moisture resistance
- Excellent machinability (fine surface finishes)
Disadvantages
- Limited mechanical strength compared to metals
- Sensitive to strong acids
- Limited use temperature (~100 °C)
Typical use cases
- Gears, bearings and bushings
- Guide parts and slides
- Food-grade components (FDA compatible)
- Precision spacers and washers
PMMA (Acrylic / Plexiglas)
The transparent plastic par excellence. PMMA machines well and offers 92% optical transparency, exceeding glass. Ideal for parts requiring clarity.
Advantages
- Exceptional optical transparency (92%)
- Lightweight (1.18 g/cm³)
- UV and weather resistant
- Can be polished to crystal-clear finish
Disadvantages
- Brittle on impact (chips)
- Sensitive to solvents (acetone, alcohol)
- Scratches easily without treatment
Typical use cases
- Display cases and showcases
- Optics and lenses
- Illuminated signs
- Transparent prototypes and models
Wood (beech, oak, MDF)
A natural and warm material that CNC machines easily. Beech and oak offer good mechanical properties, while MDF is more homogeneous and affordable.
Advantages
- Natural, aesthetic and warm material
- Easy and fast to machine
- Affordable (especially MDF and plywood)
- Can be varnished, painted or oiled
Disadvantages
- Moisture sensitive (swelling, warping)
- Variable properties depending on wood species
- Dust management required (extraction needed)
Typical use cases
- Architectural models
- Furniture and decorative pieces
- Casting molds and patterns
- Signage and displays
How to choose?
Lightweight and versatile metal parts → Aluminum 6061
Robust mechanical parts at the best price → Steel S235
Precision parts with beautiful appearance → Brass
Low-friction plastic mechanical parts → POM (Delrin)