Materials · Metals · Plastics · Selection guide
CNC machining materials
The CNC machining materials we stock and machine every week, from aluminum 6061 to titanium Grade 5 and PEEK, with properties, typical uses, relative cost and machinability, plus a short method for choosing between them.
CNC machining materials comparison
The table lists every standard material in our range. Relative cost combines raw material price and machining time, because a cheap material that machines slowly can still produce an expensive part. Machinability is relative to free-machining brass and aluminum, which cut fastest. Other grades can be sourced on request, and material (mill) certificates are available for any order.
| Family | Grade | Key properties | Typical uses | Cost | Machinability |
|---|---|---|---|---|---|
| Aluminum | 6061-T6 | Good strength, corrosion resistant, weldable, anodizes evenly | Brackets, housings, fixtures, general parts | Low | Excellent |
| Aluminum | 7075-T6 | Very high strength-to-weight, harder, poor weldability | Aerospace-style structures, high-load brackets, drone and robotics frames | Med | Excellent |
| Aluminum | 5052 | Formable, good marine corrosion resistance, lower strength | Sheet metal enclosures and panels | Low | Fair (gummy) |
| Aluminum | 2024 | High strength and fatigue resistance, weaker corrosion resistance | Structural and fatigue-loaded parts | Med | Good |
| Stainless | 303 | Free-machining, moderate corrosion resistance | Shafts, fittings, fasteners, turned parts | Med | Good |
| Stainless | 304 | General-purpose corrosion resistance, weldable | Food equipment, enclosures, brackets | Med | Fair |
| Stainless | 316 | Better chloride and chemical resistance than 304 | Marine, medical, chemical and outdoor parts | Med–High | Fair |
| Stainless | 17-4PH | Precipitation hardening, high strength with good corrosion resistance | Valve parts, shafts, high-load components | High | Fair |
| Steel | 1018 | Low carbon, easy to weld, case hardenable | Fixtures, spacers, general mechanical parts | Low | Good |
| Steel | 1045 | Medium carbon, stronger, can be hardened | Shafts, gears, pins | Low | Good |
| Steel | 4140 | Chromoly alloy, tough, heat treatable | Tooling, high-stress shafts, axles | Low–Med | Fair–Good |
| Copper alloy | Brass C360 | Free-machining, good corrosion resistance, decorative | Fittings, valves, connectors, knobs | Med | Excellent |
| Copper | C110 | High electrical and thermal conductivity, soft | Busbars, heat spreaders, electrodes | Med–High | Fair (gummy) |
| Titanium | Grade 2 | Commercially pure, excellent corrosion resistance | Chemical, marine and medical parts | High | Fair |
| Titanium | Grade 5 (Ti-6Al-4V) | Very high strength-to-weight, biocompatible, heat resistant | Aerospace, medical, motorsport parts | High | Difficult |
| Plastic | POM (Delrin) | Stiff, low friction, dimensionally stable | Gears, bushings, jigs, sliding parts | Low | Excellent |
| Plastic | PEEK | High temperature, chemical resistant, strong | Medical, semiconductor, high-temp insulators | High | Good |
| Plastic | Nylon | Tough, wear resistant, absorbs moisture | Wear pads, rollers, bushings | Low | Good |
| Plastic | PC | Impact resistant, transparent grades available | Covers, windows, guards | Low–Med | Good |
| Plastic | ABS | Low cost, easy to finish | Prototype housings, fit-check models | Low | Good |
| Plastic | PTFE | Very low friction, chemically inert, soft | Seals, gaskets, insulators | Med | Fair (creeps) |
CNC material selection: how to choose
There is no single best material for CNC machining. Work through the requirements in order, and stop at the first material that meets them all, because the cheapest suitable material usually wins.
- Strength and stiffness. 6061-T6 covers most brackets and housings. Step up to 7075-T6 or 2024 for higher loads at low weight, and to 4140, 17-4PH or titanium Grade 5 when aluminum is not strong enough. Note that stiffness (elastic modulus) barely changes within a family: 7075 is stronger than 6061 but bends almost the same under the same load.
- Weight. Density is roughly 2.7 g/cm³ for aluminum, 4.4 for titanium, about 7.9–8.0 for steel and stainless, and about 8.5–8.9 for brass and copper. Plastics are 1–2.2 g/cm³.
- Corrosion. Anodized aluminum is fine indoors and in mild outdoor use. 304 handles general wet environments; 316 or titanium for salt water and chemicals. Carbon steel always needs a coating.
- Temperature. Aluminum loses strength well above about 150 °C. Stainless, titanium and PEEK hold up at higher temperatures; POM, nylon, ABS and PC are limited to moderate service temperatures.
- Electrical and thermal. Copper C110 for conductivity, aluminum as a lighter, cheaper alternative. PEEK, POM and PTFE for insulation.
- Cost. Machining time often outweighs stock price. Titanium and 17-4PH cut slowly and wear tools; 303 machines much faster than 304 or 316 if its lower corrosion resistance is acceptable. See what drives CNC machining cost.
Tip: a 6061-T6 prototype is a quick and inexpensive way to check fit and function before committing to 7075, stainless or titanium for the final part.
Material and finish go together
Choose the finish at the same time. Only aluminum can be anodized; stainless benefits from passivation; carbon steel needs plating or powder coating; brass is often nickel plated. Plastics are usually left as machined. The surface finishes chart lists compatible combinations, and the anodizing guide explains how 6061 and 7075 differ in color.
Plastics are not just cheap metal
Engineering plastics expand with temperature far more than metals and can move after machining as internal stresses relax. Tolerances on plastic parts are usually looser than on the same geometry in aluminum, and thin walls deflect under cutting forces. Nylon absorbs moisture and grows; POM is the most stable common choice. Our plastics page covers these limits in detail.
Material guides
Go deeper by material
Aluminum
The default for prototypes and housings. Grade comparison, tolerances and anodizing.
303 · 304 · 316 · 17-4PHStainless steel
Which grade to pick for corrosion, strength and machining cost, plus passivation.
Grade 2 · Grade 5Titanium
Why titanium costs more, design tips and finishes for Ti-6Al-4V parts.
PEEK · POM · Nylon · PC · ABS · PTFEPlastics
Tolerances, stress relief and selection for machined engineering plastics.
FAQ
Material questions
What is the best material for CNC machining?
For most parts it is aluminum 6061-T6: it machines quickly, is low cost, resists corrosion and anodizes well. Choose another material only when strength, temperature, corrosion or conductivity requirements rule 6061 out.
Can you machine a material that is not on your list?
Yes. Other grades can be sourced on request. Specify the grade and any standard on the drawing, and the quote will confirm availability and lead time.
Do you provide material certificates?
Yes, material (mill) certificates are available on request. Mention it in your RFQ so it is included with the shipment.
Is 7075 always better than 6061?
No. 7075-T6 is much stronger, but it costs more, cannot be welded well and anodizes with a slightly different color. Its stiffness is almost the same as 6061, so it does not reduce deflection.
Which material is cheapest to machine?
Free-machining materials such as 6061 aluminum, brass C360 and POM usually give the lowest part price because they cut fastest with little tool wear. Titanium and 17-4PH are at the other end.