Wholesale aluminum CNC parts: alloys, tolerances and what to verify

The grade decides machinability, corrosion behavior, and whether you can anodize the part. 6061-T6 is the default for brackets, housings, and fixtures: it machines cleanly, welds, and takes a hard anodized coating. Tensile strength sits near 310 MPa, which is enough for most structural work.

For thin walls and light parts, 5052 and 5083 hold up better against salt water. They machine slower and tend to gum up taps, so keep thread depths generous. 6063 is common on heat sinks and frames where surface finish matters more than strength.

When weight matters more than cost, 7075-T6 gives you roughly 570 MPa tensile and excellent fatigue life. It also costs more, machines with more tool wear, and cannot be welded. Use it for aircraft fittings, drone arms, and high-load brackets.

2024 machines to a fine finish and is common in aerospace, but its copper content makes it corrode faster outdoors unless you anodize or prime it. ADC12 is a die casting grade, not a billet grade, so do not spec it for machining from plate.

On production aluminum parts we hold ±0.005 mm on critical features. That number only applies to features you actually dimension that way. Blanket tolerancing the whole drawing to ±0.005 mm raises cost with no functional gain. Call out the fits that matter and let the rest follow the title block.

Five-axis work pays off when a part has angled faces, deep pockets, or features on five sides. One setup means fewer datum shifts and tighter position control. We run 16 simultaneous five-axis centers, 12 four-axis mills, 27 three-axis machines, and 16 mill-turn centers, so the routing is matched to the geometry rather than forced onto one machine.

Size ceiling is 4,000 mm of travel. Long extrusions, rails, and frame members fit on the large machines; small connector bodies and sensor housings run on the compact 500 × 500 × 450 mm and 500 × 310 × 200 mm platforms. A Ø400 mm rotary table handles round and index features.

Threads, bores, and sealing faces are where aluminum bites back. Thin walls deflect under clamping, and deep bores wander if the tool is too long. Tell us the wall thickness and we will adjust fixturing and step-downs before the first chip.

Machining is rarely the last step. Anodizing, plating, and coating all change dimensions slightly and can hide or expose surface defects. Hardcoat anodize builds roughly half in and half out, so a tight bore can close up. Flag any bore or thread that must stay on size after coating.

We handle clear, color, hardcoat, and conductive anodizing, plus electroless nickel, zinc, silver, and gold plating. Powder coating, black oxide, bead blasting, tumbling, brushing, and polishing are available. Laser marking works at a minimum character height of 1.5 mm, so keep part numbers readable at that size.

As-machined finish lands around Ra 1.6–3.2 μm. A high-quality finish runs Ra 0.8–1.6 μm, and fine finishing reaches Ra 0.2–0.8 μm on sealing faces and optical mounts. Each step up means slower passes and more inspection time, so spec the finish the function needs.

One supplier handling machining and finishing removes the shipping step between shops. That matters on cosmetic parts, where a scratch picked up in transit becomes a rejected lot.

Ask for the inspection plan, not just a certificate. We inspect 100% of parts before shipment, with raw material checks, in-process monitoring, and a final inspection. Reports go out on request. If a supplier only inspects a sample at the end, a bad setup can run for hours before anyone notices.

Check how change is handled. On a 10,000-part run, a tool change or a material lot switch should trigger a first-article check. Ask who signs off on that, and whether you get the data.

Lead time matters as much as price. We return a quotation and free DFM analysis within 12 hours, and production can start within 24 hours. Parts ship in 3–5 days. Our historical late-delivery probability is below 2%.

Confidentiality is part of the package. Uploads stay secure, and we sign an NDA on request. For defense and medical work, that should be settled before drawings move.

There is no minimum order quantity. One prototype and a 10,000+ part run go through the same process. Volume pricing comes from fixturing and setup spread across the lot, not from cutting corners on the first article.