3 Axis CNC Machining Aluminum

Why aluminium needs its own process

Aluminium is the forgiving end of the spectrum: it cuts fast, conducts heat away from the edge, and is easy on tools. That does not make it free of problems — it changes which problems appear. The ones that actually cost money are built-up edge at low cutting speed, chip evacuation in deep pockets, and thermal movement on a tight-tolerance part. Because the metal removes so quickly, setup time becomes a larger share of the unit cost, so batch size dominates price more than it does on steel.

Cast plate and wrought bar also behave differently after stress relief and can move by different amounts once machined, which is worth stating on the drawing when flatness matters. The practical point is that aluminium's "easy" reputation hides a tolerance problem: the part is stable, but only after it has returned to ambient and been measured there.

Which grades are used, and why

Your grade selection is usually settled by the service environment — corrosion, strength, or temperature — and only then by machinability. If you choose on machinability first, your part meets the drawing and fails in service. The grades that come up in practice:

Grade (typical)	Where it earns its keep	Machining note
6061-T6	General brackets, housings, anodised parts	The default; good chip control, finishes clean
7075-T6	High-strength structural, fixtures	Stronger but more prone to tearing; needs sharp tooling and care on thin sections
6082	Structural work in Europe	Slightly stronger than 6061; good all-rounder
2024 (T3/T4)	Fatigue-critical, aerospace secondary	Poor corrosion resistance; often clad; machined like 7075
5083 / 5052	Marine, weldments	Work-hardens; moderate, gummy at the cut
Cast plate (e.g. A356-T6)	Near-net blanks from a casting	Watch porosity; probe stock before final passes

The values above are typical published figures for the common tempers. Confirm the actual lot against the mill certificate — temper and specification move the numbers, and the certificate is what the assembly sees.

The cutting mechanism, and what it demands

Aluminium's low specific cutting force and high thermal conductivity let it run at high surface speed with a generous chip load. The failure mode is built-up edge: at too low a speed the chip welds to the tool, the edge roughens, and finish and tolerance degrade together. The response is the opposite of what intuition from steel suggests, keep speed up, keep the chip load positive, and use polished flutes or a tool coating that resists adhesion. Chip packing in a deep pocket is a second, separate problem: it is solved by tool geometry and coolant delivery, not by slowing down.

DFM tips specific to aluminium

Most cost on an aluminium part is decided at the drawing, before the first chip:

• Internal corner radius — match it to a real cutter diameter; a sharp corner forces a smaller tool and far more passes.
• Wall thickness — a 1 mm wall on a large pocket will flex under cutting pressure even in aluminium; holding it flat costs a slower finishing pass. Open the wall where function allows.
• Pocket depth — keep it within roughly 3–4× the tool diameter, or the tool gets long, flexible, and slow.
• Thermal expansion — at ~23 × 10⁻⁶ /K, a long thin part measured warm will not match the drawing. Take the finishing pass and the measurement at 20 °C.
• Anodising allowance. Type II adds roughly 5–15 µm per surface; state it on threaded and press-fit features so the coating does not close the fit.

How the part moves after the cut

High thermal expansion means a part measured warm will measure differently when cool. On a tight-tolerance part the finishing pass is taken after the part has returned to ambient, and the measurement is taken at 20 °C. The general rule is that a tolerance is held by the process, not by the machine: where a feature is tight, the finishing pass is separated from roughing, the part is allowed to stabilise, and the measurement is taken at a controlled temperature.

Finishing and surface treatment

Anodising (Type II and Type III hardcoat), chem film, and powder coat are all routine. Type II adds roughly 5–15 µm per surface, which must be allowed for on threaded and press-fit features. Finishing is specified on the drawing, not assumed at the end — a coating applied after inspection changes the fit, so the allowance belongs on the drawing, not in a note at the back of the quote.

Tool consumption and cycle time

Because aluminium removes so quickly, setup time is a larger fraction of cost and batch size dominates the unit price. The lever that moves cycle time most is design, not tooling: pocket depth, corner radius, and wall thickness change cycle time more than any insert choice, because they determine the tool that can be used and therefore how much material can be removed per minute.

Tolerance, and the instrument behind it

Milling and turning hold ±0.003 mm (milling) / ±0.002 mm (turning); precision grinding and wire EDM hold ±0.002 mm. A tolerance is only worth as much as the instrument that verifies it, so the floor runs 20+ inspection instruments alongside the machines. CMM for dimensional and true position, vision and profile instruments for surface and geometry, hardness testers and coating gauges for heat treatment and plating, and XRF for incoming material composition against the mill certificate. The rule that matters on a drawing is that a tolerance is held by the process, not by the machine.

How much capacity sits behind it?

more than 100 machines with depth in every relevant family — 50+ three-axis, 20+ four-axis, 20+ five-axis, 25+ turning centres, plus Swiss-type, grinding, and wire EDM. Having several machines in that family is what lets a part move to another lane rather than sit in a queue when a machine is pulled for service, which is what protects a delivery date.

What is certified, and what is deliberately not?

Three certificates, each with a number you can check with the registrar: ISO 9001:2015 (116024/A/0001/UK/En), IATF 16949:2016 (131941/A/0001/SM/En), and ISO 14001:2015 (116024/B/0001/UK/En).

The IATF 16949 certificate excludes clause 8.3 (product design). That is normal for a build-to-print manufacturer and it is stated here rather than left for an auditor to discover: the plant manufactures to your design, it does not originate the design.

Which entity is responsible for the work?

Dongguan Zhuohang Ltd, Registration No. 91441900MA4UWT6X39, established 2005, operating as Zhuohang Precision Machining Factory. Check any Chinese manufacturer with that 18-character code on the National Enterprise Credit Information Publicity System: a trader's licence shows a trading scope and an office address, not a plant.

What the extra axes actually buy

The axis count is about setups, not precision. A 3-axis machine cuts from one direction, so a part with features on several faces needs to be re-fixtured between operations - and every re-fixture introduces a small error. A 4-axis machine adds rotation, and a 5-axis machine can reach five sides in one setup, so the features on several faces stay in the same coordinate frame and line up. For a part that is a prismatic block, 3-axis is enough and cheapest; for a part with angled or multi-face features, the extra axes buy accuracy and fewer operations. You choose the axis count for the geometry, not by habit.

How to read an axis-based quote

If a part genuinely needs 5-axis work, the quote reflects one setup and tighter feature relationships; if a shop puts a 3-axis part on a 5-axis machine and charges for it, you are paying for capability the geometry does not use. This floor runs 3-, 4- and 5-axis machines including the Mazak VARIAXIS I-600 five-axis and the INTEGREX I-250H S mill-turn, at ±0.003 mm milled. Contact Felipe Iglesias at [email protected] or +86 13126536955 with the drawing and ask which axis count the geometry actually justifies.

What this shop actually runs

Capability evidence should come as specifics, not slogans. Behind this guide is a 6,800 m2 plant in Dongguan, China running 100+ CNC machines with 100+ staff. The machine list by category:

• 5-axis machining centres (10+) - Mazak VARIAXIS I-600 (510/910/510 mm travel, 12,000 rpm, 22 kW, 71.6 N·m, 30-tool BT40) and Mazak INTEGREX I-250H S (B-axis 0.0001°, 24 kW, 124 N·m, 38-tool HSK-A63). Cut on compound-angle parts, single-setup multi-face prismatic work, and aerospace fittings where datum transfer loss is unacceptable.
• 3-axis / 4-axis machining centres (50+) - Brother SPEEDIO S500Z2N / S700Z2N (10,000 rpm, 14/21-tool ATC, 0.7 s tool-to-tool, Z-axis 2.2 G) and Mazak VCE-430A L / VCE-570C L (10,000 rpm, 118 N·m, 24-tool ATC). Cut on prismatic parts, plates, brackets, housings.
• Swiss-type turning centres (10+) - Citizen Cincom A20-3F7 (Φ20 mm, 10,000 rpm), TSUGAMI B0206-III / B0205-III (Φ20 mm, 0.1 µm), STAR SR-32JII / SR-32J Type N (Φ32 mm, 8,000 rpm). Cut on long, slender rotational parts at ±0.002 mm.
• CNC turning centres (20+) - HEADMAN T70M/1250 (720 mm swing, 117 mm bore, 3,000 rpm, BMT75 12-station turret). Cut on shafts, bushings, flanges up to ±0.002 mm.
• Wire EDM (5+) - Sodick AQ535L (550/350/300 mm travel, ±20° taper, 800 kg workpiece). Cut on hardened tool steel, internal splines, sharp internal corners that milling cannot reach.
• Inspection: Hexagon CMM + 20+ gauges - Hexagon CMM for coordinate measurement, plus vision system, profilometer, hardness tester, coating thickness gauge, XRF for material verification. The 10:1 rule (gauge 10x more accurate than the band) is applied to every feature.
• Machine highlights - VARIAXIS I-600: one-setup multi-face 5-axis + MAZA-CHECK auto-calibration; INTEGREX I-250H S: DONE-IN-ONE mill-turn, B-axis 0.0001° + Ai thermal shield; SPEEDIO S500Z2N / S700Z2N: Z-axis 2.2 G + 0.7 s ATC; Swiss-type: guide-bush switchable + 0.1 µm resolution.

Tolerance: ±0.003 mm CNC milling / ±0.002 mm CNC turning / ±0.002 mm grinding and wire EDM. Capability: Ppk >= 1.67 initial on key characteristics, Cpk >= 1.33 ongoing.

Certificates: ISO 9001:2015 (116024/A/0001/UK/En), IATF 16949:2016 (131941/A/0001/SM/En, with design clause 8.3 excluded, stated openly) and ISO 14001:2015 (116024/B/0001/UK/En), issued to Dongguan Zhuohang Ltd, registration 91441900MA4UWT6X39, founded 2005.

Where we ship: Austria, Belgium, the Czech Republic, Denmark, France, Germany, Greece, Hungary, Ireland, Italy, the Netherlands, Spain, Sweden and the United Kingdom in Europe; Brazil, Canada, Mexico and the United States in the Americas; China, Israel, Japan, Singapore and Sri Lanka in Asia; Australia and New Zealand in Oceania; and South Africa in Africa — plus other countries and regions worldwide, shipped from our base in Dongguan, China.

Contact: Felipe Iglesias, [email protected], +86 13126536955.

Frequently Asked Questions

Standards referenced on this page

• ASTM B211/B211M-19 — Standard Specification for Aluminum-Alloy Rolled or Cold Finished Bar, Rod, and Wire
• ASTM A582/A582M-12 — Standard Specification for Free-Machining Stainless Steel Bars
• ISO 9001 — Quality management systems — Requirements