CNC Machining Materials | Metal & Plastic

Surface finish? See our Ra roughness chart for achievable values and cost by finish level.

Machining titanium? See our titanium machining guide for speeds, tooling and the fire precautions.

Choosing a material? See our side-by-side aluminium vs stainless steel vs titanium comparison for specific strength, machinability and real cost ratios.

Materials We Machine

We work with the full range of engineering materials used in OEM products: aluminum, stainless steel, carbon and alloy steels, brass, copper, titanium, and engineering plastics. Below are our most common grades with typical applications, finish options, and machining notes. For a focused guide on machining aluminum parts — grades, tolerance and anodizing — see our aluminum CNC machining guide. These same alloys feed the parts we machine across our industries — from automotive EV housings to aerospace brackets and satellite hardware.

Aluminum

Aluminum 6061 / 6063 / 7075 / 2024

The default choice for lightweight structural parts, housings, brackets and enclosures. Excellent machinability, good corrosion resistance, and accepts a wide range of finishes.

Common grades and uses

6061-T6 — General purpose, structural, housings, brackets.
7075-T6 — High strength, aerospace and robotics load-bearing parts.
2024 — Aerospace structures, fatigue-resistant parts.
6063 — Architectural and decorative extrusions, light structural.

Available finishes

Type II anodize (clear / black / colors), Type III hardcoat anodize, chem film (chromate), powder coat, bead blast, brushed / polished, laser marking.

Stainless Steel

Stainless 304 / 316 / 17-4PH / 420 / 303

For parts requiring corrosion resistance, high strength, or medical / food-grade compliance. 17-4PH offers high strength and is often used for shafts and aerospace components.

Common grades and uses

304 — General purpose, food equipment, decorative.
316 — Marine, medical, chemical exposure.
17-4PH (H900 / H1025) — High-strength shafts, aerospace, tooling.
420 — Hardenable, wear-resistant cutting edges and tools.
303 — Free-machining, best for high-volume screw-machine parts.

Available finishes

Passivation (ASTM A967), electropolishing, mirror polish, bead blast, tumbled, brushed.

Brass & Copper

Brass C3602 / C3604 / H59 / H62 · Copper C1100 / C1220

Excellent for electrical and thermal conductivity applications, decorative components, and precision instrument parts. Free-machining brass (C360) is the easiest material to machine — fast cycle times, long tool life. See our brass CNC machining guide for the grades, tolerances and finishes we run on brass parts.

Common grades and uses

C3602 / C3604 (free-machining brass) — Connectors, fittings, instrument parts.
H59 / H62 — Decorative, plumbing fittings, valves.
C1100 (pure copper) — Electrical conductors, bus bars.
C1220 (DHP copper) — Heat exchangers, plumbing.

Available finishes

Polished, satin, antique / aged patina, tin plating, nickel plating, gold flash, clear lacquer.

Engineering Plastics

POM / PEEK / Nylon / PC / PTFE / ABS / Acrylic / UHMW

Plastics offer low weight, electrical insulation, low friction, and chemical resistance. We machine them in rod, plate and sheet form to close tolerances — ideal for prototypes and small-batch production where injection molding is uneconomical. See our plastic CNC machining guide for the grades we run and the tricks that keep them in tolerance.

Common grades and uses

POM (Delrin / Acetal) — Gears, bearings, low-friction sliding parts.
PEEK — High-temp (up to 260°C), aerospace, medical implants.
Nylon (PA6 / PA66) — Wear strips, rollers, structural insulators.
PC (Polycarbonate) — Housings, transparent covers, impact-resistant parts.
PTFE (Teflon) — Chemical seals, gaskets, low-friction surfaces.
ABS — Enclosures, prototypes, jig/fixture components.
UHMW-PE — Wear strips, guides, food-grade components.

Available finishes

As-machined, bead blast, polished, painted, anti-static coating.

Reference

Material Machinability Quick-Reference

Relative machinability compared with aluminum 6061 (≈100). Higher means faster, lower-cost cutting; lower means more tool wear and longer cycle times. Tighter tolerances are achievable on rigid, temperature-controlled setups.

Material	Machinability (6061=100)	Typical tolerance	Common use
Aluminum 6061	100	±0.02 mm	Structural, housings, brackets
Aluminum 7075	70	±0.02 mm	Aerospace, robotics load parts
Brass C360	200	±0.02 mm	Connectors, fittings, instruments
Stainless 304	45	±0.02 mm	Food, medical, decorative
Stainless 17-4PH	35	±0.02 mm	High-strength, aerospace shafts
Titanium Ti-6Al-4V	25	±0.03 mm	Aerospace, medical implants
PEEK	50	±0.1 mm	High-temp, medical, aerospace

Approximate values for planning only; final cycle time depends on geometry and tooling. Property data from MatWeb. Choosing a grade? See our material selection guide.

Real Production Samples

Parts We've Actually Cut Recently

Three examples from the shop floor — the kind of parts that show what each material can do when it is machined well, not catalog renderings.

Custom stainless steel CNC machined shaft and flange — 304/316 OEM part example — **Stainless steel — shaft & flange**
A 304/316 shaft with turned flange and milled register. See CNC turning.

Brass CNC turned parts — threaded inserts, knurled components, sleeves — **Brass — turned inserts & knobs**
C360 free-machining brass, knurled grips, threaded fasteners. See brass & copper above.

Custom aluminum 6061 manifold blocks — CNC milled housings — **Aluminium — 6061 manifold blocks**
Milled, drilled and tapped housings. See aluminum CNC guide.

Grid of precision CNC machined aluminum parts — brackets, housings and fittings — **Aluminium — precision grid**
Brackets, housings and fittings in 6061/7075. See aluminum CNC guide.

Mixed-metal CNC turned parts collection — brass, stainless and steel components on one tray — **Mixed metals — turned set**
Brass, stainless and steel in one batch. See CNC turning.

POM (Delrin) CNC machined flange hub — engineering plastic turned component — **Plastic — POM flange hub**
Acetal turned to a clean edge. See plastic machining guide.

FAQ

Frequently Asked Questions

Can you supply material, or do I need to provide it?

We supply material for almost every job. We keep common aluminum, steel, brass and plastic grades in stock and source specialty alloys through certified mill channels. Material certificates are available on request. Customer-supplied material is also accepted.

Do you work with certified or aerospace-grade materials?

Yes. We work with mill-certified aerospace alloys (7075-T7351, 2024-T3, Ti-6Al-4V, 17-4PH H1025) and can provide full material traceability documentation.

What tolerances can you hold on plastic parts?

Standard plastic machining tolerance is ±0.1mm due to thermal expansion. Tighter tolerances (±0.05mm) are possible on small features with temperature-controlled machining.

Can you advise which material is right for my application?

Yes. Tell us the operating environment, load, temperature and regulatory requirements, and our engineers will recommend 2–3 material options with cost and lead-time trade-offs.

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Deep-dive guides

Material-Specific Machining Guides

Per-alloy guides with grades, tolerances and finishes: aluminum CNC machining, stainless steel CNC machining, steel CNC machining, brass CNC machining, titanium machining, Inconel & Hastelloy CNC machining, and plastic CNC machining.

References: MatWeb — material property database