CNC machined aluminum parts

Aluminum CNC machining service for prototypes and low-volume runs

Aluminum is the default material for machined brackets, housings, heat sinks, fixtures and enclosures. It cuts fast, holds tolerance well, is light (about one third the density of steel) and anodizes into a hard, corrosion-resistant surface. For most CNC aluminum parts the machine time is short, so the price is driven more by setups, tolerances and finishing than by the metal itself.

We machine aluminum on 3-, 4- and 5-axis mills and on lathes and mill-turn centers. Standard tolerance is ±0.03 mm; tighter tolerances on critical features are possible when called out on the drawing and confirmed in the quote. Every order ships with an inspection report on critical dimensions, and mill certificates are available on request.

6061 vs 7075 vs 5052 vs 2024: grade comparison

Typical room-temperature properties for plate and bar. Values are textbook typicals, not guaranteed minimums; check the relevant ASTM/EN standard if your design depends on them.

6061-T6: the default

If the drawing says only "aluminum", 6061-T6 is usually the right answer. It machines cleanly, is widely stocked in plate, bar and tube, anodizes evenly in clear, black and colors, and can be welded (with a loss of temper in the heat-affected zone). Choose it unless you have a specific reason not to.

7075-T6: when strength matters

7075-T6 has roughly 80% higher yield strength than 6061-T6 at almost the same weight, and machines just as well, often with a better surface finish. Trade-offs: it costs more as raw stock, it is not suitable for fusion welding, its corrosion resistance is lower, and clear anodize can come out with a slightly different tone than on 6061. Use it for parts that see high static loads, such as clamps, structural brackets and mounts where stiffness is fixed but stress is high. Note that stiffness (Young's modulus, about 69–72 GPa) is almost identical across all aluminum grades; switching to 7075 does not reduce deflection.

5052: formable and corrosion resistant

5052 is a non-heat-treatable alloy mostly used as sheet. It bends well without cracking and resists salt water, which makes it a standard choice for sheet metal enclosures and brackets. As a machined block it is soft and gummy, so it is a poor choice for complex milled parts.

2024: fatigue strength, poor corrosion

2024 has high strength and good fatigue resistance, the reason it is used in aerospace structures. Its high copper content means low corrosion resistance and uneven, often blotchy anodizing. Specify it only when a drawing or legacy design calls for it.

Design tips for CNC milling aluminum parts

• Inside corner radii. Pockets are cut with round end mills. Give internal vertical corners a radius of at least one third of the pocket depth, and use the same radius throughout so one tool finishes the part.
• Pocket depth. Keep pocket depth under about 4× the tool diameter. Deep, narrow pockets need long tools that deflect and chatter.
• Wall thickness. Aim for 1.0 mm (0.04 in) or more on metal walls; 0.5 mm is possible on short walls but slows machining and can distort.
• Threads. Tapped threads in aluminum strip more easily than in steel. Use a thread engagement of at least 1.5× the diameter, or specify helical inserts for threads that will be assembled many times.
• Tolerances. Call out tight tolerances only where parts mate. General dimensions can follow ISO 2768-m. See our tolerance guide.
• Thin plates. Large thin plates move when material is removed from one side. Flatness better than about 0.05 mm over 100 mm needs a note on the drawing so we can plan stress relief and flipping.

Each quote includes free DFM notes that flag features that add cost or risk. More detail on milling and turning is on the CNC milling and CNC turning pages, and our cost guide explains what drives the price.

Finishes for aluminum