Aluminum CNC Parts Machining

The first decision on any aluminum job shapes everything downstream: the alloy. 6061-T6 is the default for brackets, housings and fixtures because it machines clean, welds, and holds ±0.005 mm on a stable setup. Yield strength sits near 276 MPa, which is enough for most structural work without the tool wear that comes with harder grades.

2024 and 7075 raise strength but change the shop floor. 7075 cuts at 7075 speeds with sharp carbide and light radial engagement; let it rub and you get chatter on the floor and a poor finish on the wall. 2024 machines well but has lower corrosion resistance unless it is anodized or plated. Neither grade likes a deep finishing pass with a long reach tool.

Casting alloys such as ADC12 behave differently. Porosity is common, so a machined surface may open small voids after anodizing. If the part needs a cosmetic finish, tell us and we will pick a billet grade instead. 5052 and 5083 are for formed or welded parts, not for tight-tolerance features.

GreatLight stocks 6061, 6061-T6, 2024, 5052, 5083, 6063, 6082, 7075 and ADC12. Material certificates ship with the inspection report on request. If you are not sure which grade fits, send the drawing and we will come back with a recommendation and a free DFM note within 12 hours.

A three-axis mill cuts from one direction. Every new face means a new fixture, a new zero, and a new chance for stack-up error. That is fine for a plate with holes and a pocket. It gets expensive when the part has angled bores, contoured flanges or features on five sides.

Simultaneous 5-axis changes the math. The tool reaches the feature without re-clamping, so the datum never moves. We run 16 simultaneous 5-axis machining centers with a Ø400 mm rotary table, plus 12 four-axis mills, 27 three-axis machines and 16 mill-turn centers. Total capacity is 127 high-precision CNC machines across three plants.

The trade-off is programming time and tool access. A 5-axis setup usually costs more to program than a 3-axis one, so it only wins when it removes two or more fixtures, or when the geometry cannot be reached any other way. For a simple bracket, 3-axis with a soft jaw is faster and cheaper.

Size matters too. Our largest travel is 4,000 × 400 × 150 mm for long extrusions and rails. Medium work covers 750 × 1,150 × 550 mm and 600 × 600 × 600 mm. Compact cells handle 500 × 500 × 450 mm and 500 × 310 × 200 mm. Tell us the envelope early; it decides which cell the job lands in.

Aluminum cuts fast, which tempts designers to push wall thickness down. In practice, a 1 mm wall on a 100 mm long part will deflect under cutting force and ring during inspection. For unsupported walls, 1.5 mm to 2 mm is a safer floor on a 6061 part. Add a rib or a boss if you need less.

Deep pockets have a similar limit. A tool needs roughly three times its diameter in reach before it starts to deflect. A 6 mm end mill cutting 18 mm deep is workable with a stub holder. Push to 40 mm and you need a necked tool, lower feed, and more passes. That shows up in the price.

Threads are straightforward. We cut M2 and up with a form tap or a thread mill, and thread milling is the better choice near a wall or a thin floor because it cuts with less radial force. Minimum character height for laser marking is 1.5 mm, so plan part numbers accordingly.

Tolerances hold at ±0.005 mm (±0.0002 in) on critical features when the setup supports it. That is not a blanket number for every dimension on the drawing. Mark the two or three features that matter; holding everything to that band adds cost and time for no gain.

As-machined aluminum lands around Ra 1.6–3.2 μm. A finishing pass with a sharp tool and light depth of cut gets to Ra 0.8–1.6 μm, which is the common callout for mating faces. Fine work reaches Ra 0.2–0.8 μm, but it costs time and is usually reserved for sealing surfaces or optical mounts.

Anodizing is the most requested finish: clear, color, hardcoat or conductive. Hardcoat adds 0.025 mm to 0.05 mm per side, which matters on a bore or a thread. Tell us the masked areas and we will build the growth into the pre-plate dimensions. Electroless nickel, zinc, silver and gold plating are also available, along with powder coating, black oxide, bead blasting, tumbling, brushing and polishing.

Inspection runs 100% before shipment. Raw material check, in-process monitoring, final inspection, and reports on request. If you need first article data or a CMM report, say so on the PO and we build it into the routing rather than adding it at the end.

Every job ships with the confidentiality default on. Files stay internal, and we sign an NDA on request. No minimum order quantity applies, so a single prototype and a 10,000-part run go through the same inspection path.