Can CNC Machine Cut Metal?

A CNC machine does not cut metal the way a saw or a laser does. It drives a rotating cutting tool into a workpiece along programmed paths, and the material leaves as chips. The tool has cutting edges, and those edges shear material ahead of them. Heat goes into the chip, the tool, and the part, in that order of share.

That single fact explains most of what follows. Hard alloys push the tool harder and generate more heat, so feeds and speeds drop, cycle time rises, and tool wear becomes the main cost driver. Soft alloys cut fast but can gum up on the tool, so you trade speed for surface quality and chip control.

Milling covers flat faces, pockets, slots, and complex 3D contours. Turning covers round parts: shafts, bushings, fittings, and threaded bodies. Mill-turn centers do both in one setup, which matters when a part has a turned bore and a milled flange that must stay concentric.

A three-axis mill handles the majority of prismatic work. Reach for four or five simultaneous axes when the part has undercuts, deep angled pockets, or features on several faces that would otherwise need three or four separate setups.

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  3-axisFlat plates, housings, brackets, simple pockets. Fastest and cheapest per part.
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  4-axisCylindrical parts with flats, cross holes, or slots around a bore.
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  5-axis simultaneousCurved surfaces, deep cavities, impellers, medical and aerospace contours.
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  Mill-turnOne-and-done round parts with milled features and tight concentricity.

Aluminum is the easiest common metal to machine. Grades like 6061 and 6082 cut at high speed with good finishes, and 7075 gives higher strength at the cost of more tool wear. Watch for thin walls on 6061: it moves under clamping pressure, and a wall thinner than about 1 mm gets risky on tall sections.

Brass and copper are also forgiving. C36000 free-cutting brass machines about as well as anything on the floor, which is why it shows up in fittings and valve bodies. Pure copper (C101, C110) is gummy and needs sharp tools and generous coolant, but it cuts.

Stainless steel is where shops start to slow down. Grades 303 and 304 are manageable; 316 and 316L work-harden if the tool rubs instead of bites, so you keep the feed high enough to stay under the hardened skin. 17-4PH in the H900 condition is harder again and often needs carbide with a coating and a slower pass.

Titanium and Inconel are the hard cases. Ti-6Al-4V (TC4) conducts heat poorly, so the cutting edge takes the temperature. Inconel is worse. Both are machinable, but expect reduced tool life, longer cycle times, and a real cost premium. Send these parts out only when the geometry justifies it.

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  Tool wearThe dominant cost on titanium, Inconel, and hardened steels.
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  Work hardeningMain risk on 304, 316, and other austenitic stainless grades.
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  GummingCommon on pure copper and soft aluminum when coolant is thin.
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  DistortionThin walls and long slender parts move after the vise releases.

General machining holds ±0.05 mm without much fuss. Once you go below ±0.02 mm, the part starts to dictate the process: material stability, fixturing, temperature, and inspection all matter. Our floor works to ±0.005 mm (±0.0002 in) on parts that are designed for it. That number is not a default and it is not free.

Surface finish follows a similar pattern. As-machined surfaces land around Ra 1.6–3.2 μm. A dedicated finishing pass gets you to Ra 0.8–1.6 μm. Below that, you are usually looking at polishing, lapping, or a coating rather than a different cutter path.

Deep pockets with small corner radii are the classic accuracy killer. A cutter has to be long enough to reach the floor and stiff enough not to deflect. Those two needs pull against each other. A pocket 40 mm deep with a 3 mm corner radius needs a long, thin tool, and the wall will show it.

Threads, bores, and flatness each carry their own limits. A reamed bore holds diameter better than an end-milled one. A ground flat is flatter than a fly-cut flat. Tell us which feature carries the tolerance, because applying it to the whole drawing raises the price for no reason.

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  ±0.05 mmStandard work. Most brackets, plates, and general parts.
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  ±0.02 mmFits, mating bores, and locating features.
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  ±0.005 mmSelective features only. Needs stable material and good fixturing.
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  Ra 0.2–0.8 μmRequires extra passes or a secondary finishing step.

CNC cutting wins on tight tolerance, moderate volume, and complex geometry. It loses on very thin sheet, on parts with uniform wall thickness and no features, and on very high volumes where a die pays for itself. A stamped bracket at 200,000 pieces per year should not be milled.

Sheet metal is faster and cheaper when the part is essentially flat or a simple bend. Laser cutting and forming handle 0.5 mm to 6 mm stock at low cost, and the tolerance is usually good enough. Switch to CNC cutting when the part needs pockets, bosses, or a machined face.

Casting is the better route for a complex shape with internal cavities and no tight tolerances. Add machining after casting only where the critical faces need it. That two-step route is often cheaper than cutting the whole part from solid, especially in aluminum.

For prototypes, cutting from solid is almost always the right call. No tooling, no setup cost beyond programming, and you can change the geometry between runs. When the design settles, that is the moment to look at casting or molding.

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  Choose CNC cuttingTight tolerances, pockets, complex 3D geometry, low to mid volume.
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  Choose sheet metalFlat parts, simple bends, thin stock, high volume.
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  Choose casting plus machiningComplex internal shape, loose tolerances, machined critical faces.
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  Choose moldingHigh volume plastic or low-melt metal parts with a settled design.

Every job starts with a DFM review. We look at wall thickness, corner radii, deep pockets, and datum choice before quoting. That review goes back to you within 12 hours, and it often saves a revision cycle. Production can start within 24 hours after the design is locked.

Fixturing decides the outcome on hard parts. A thin plate gets supported underneath, not just clamped at the edges. A round part with tight concentricity goes on a mill-turn center so the bore and the flange stay true. A five-axis part gets set up once instead of four times.

Our floor runs 127 high-precision machines, including 16 simultaneous 5-axis centers and 16 mill-turn centers, across three plants in Dongguan and Singapore. Maximum processing size is 4,000 mm, with a Ø400 mm rotary table for round work. That covers most parts without breaking a setup into pieces.

Inspection runs through the whole job. Raw material gets checked on arrival, dimensions are monitored in process, and every part is inspected before shipment. Reports are available on request. Historical late-delivery probability sits below 2%.

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  DFM reviewIncluded with every quote. Sent within 12 hours.
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  Materials in stockAluminum, stainless, steel, brass, copper, titanium, plastics.
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  FinishingAnodizing, plating, powder coat, bead blast, laser marking.
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  VolumeNo minimum. One prototype to 10,000+ part runs.