PCBWay CNC Processing Guide for Engineers

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  What the PCBWay CNC processing guide covers
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  Step 1: model format and DFM review
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  Step 2: choosing three, four or five axes
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  Step 3: matching material to tolerance and finish
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  Step 4: finishing, inspection and what ships
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  Where the process stops being a good fit
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  Step by step: from upload to delivered parts
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  Which setup fits your part

The order path is short. You upload a 3D model, an engineer reviews geometry and tolerance, we return a quote with a DFM note within 12 hours, and production can start within 24 hours after you confirm. Parts normally ship in 3–5 days. Nothing here depends on your part being simple; it depends on whether the drawing and the model agree with each other.

The machining itself happens on 127 high-precision CNC machines across three wholly-owned plants in Dongguan and Singapore. That includes 16 simultaneous 5-axis machining centers, 12 four-axis mills, 27 three-axis machines and 16 mill-turn centers. The largest work envelope is 4,000 × 400 × 150 mm, so long extrusions and frame rails do not need to be split.

What this page does not do is quote a price. Price follows material, volume removed, tolerance and finish. What we can do is explain the decision points that change all four, so you can predict the outcome before the first chip is cut.

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  Quote and DFM in 12 hoursA real engineer reads the model, not a script.
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  No minimum order quantityOne prototype or a 10,000+ part run use the same route.
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  100% inspection before shipmentIncoming material, in-process and final checks.

Send a 3D solid. STEP (.stp) and IGES (.igs) are the safest, and Parasolid (.x_t) works well too. A mesh file such as STL tells the CAM software where the surface is but not where the nominal dimension is, so a hole modelled at Ø6.00 mm may arrive as Ø5.98–6.02 mm. On a bearing bore that difference matters. Add a 2D drawing in PDF or DWG when you have tolerances, datums or threads that are not obvious from the solid.

The DFM check looks at four things first: minimum wall thickness, depth-to-diameter ratio of pockets and holes, tool reach into corners, and whether the tolerance you wrote can survive the setup. A 0.5 mm wall in aluminium 6061 cuts cleanly. The same wall in PEEK will deflect under cutting force and may spring back out of tolerance. Neither is a mistake in the model; they are different materials with different stiffness.

Tolerance bands we work to are ±0.005 mm on critical features where the geometry and material allow it, and Ra 0.8–1.6 μm on a standard machined finish, down to Ra 0.2–0.8 μm when a sealing face or sliding surface needs it. As-machined surfaces sit at Ra 1.6–3.2 μm. If your drawing calls for ±0.005 mm on a 300 mm long aluminium part, expect a conversation about temperature and fixturing rather than a straight yes.

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  STEP or IGES firstMesh files hide the nominal size.
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  Add a 2D drawingNeeded for datums, threads and GD&T.
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  Flag the critical dimensionsThree or four marked features beat a fully toleranced drawing.

Axis count is a setup decision, not a quality ranking. A three-axis machine holds the part still and moves the tool in X, Y and Z. It is the right choice for plates, housings with open faces, and any part where every feature can be reached from one or two directions. It is also the fastest and cheapest way to remove material, so we often rough on three axes and finish on five.

A four-axis machine adds rotation around one axis, usually A. That suits cylindrical work: shafts, bushings, cam profiles, parts with holes on a bolt circle. The part turns, the tool stays perpendicular, and you avoid re-clamping between operations. Every re-clamp is a chance to lose position, so reducing setups is a real accuracy gain, not just a time saving.

Five-axis machining adds two rotary axes at once, so the tool can tilt and the table can rotate under simultaneous control. On an impeller, a turbine blade or a medical implant with compound curvature, the tool reaches the surface at the correct angle in one setup. The alternative on three axes is a series of fixtures and a lot of hand blending. Five-axis also lets a short, stiff tool reach deep features that a long tool cannot, which improves both finish and tool life.

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  Three axesPlates, brackets, open housings, fast roughing.
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  Four axesShafts, bushings, bolt-circle holes, cam profiles.
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  Five axesImpellers, blades, organic medical shapes, deep pockets.

Aluminium is the default for prototypes and most enclosures. We stock 6061, 6061-T6, 2024, 5052, 5083, 6063, 6082, 7075 and ADC12. The 6061-T6 grade cuts cleanly, anodizes evenly and holds ±0.005 mm on features up to roughly 150 mm. 7075 is stronger but gummier in the cut, so sharp corners and thin ribs need more care. 2024 has better fatigue behaviour and poorer corrosion resistance, which is why it is usually plated or anodized.

Stainless 303 machines the easiest of the 300 series and is the usual pick for shafts and fittings. 304 and 316L resist corrosion better but work-harden, so light finishing passes at low feed are the correct approach, not heavy cuts. 17-4PH (SUS630) gives high strength after heat treatment and is common in aerospace and medical brackets. Tool steel and 4130, 4140, 4340 appear in fixtures and drivetrain parts where hardness matters more than finish.

Titanium (TA1, TA2, TC4 / Ti-6Al-4V), Inconel and magnesium AZ31B / AZ91D sit at the difficult end. They cut hot, they wear tools, and they need slower speeds and more coolant. They are still machinable, but expect a longer cycle and a higher price per part. Plastics behave differently again: POM and PA hold dimensions well, PEEK holds temperature, and ABS and PMMA are chosen for appearance or cost rather than stiffness. Carbon fibre reinforced material is abrasive, so tool wear is the limiting factor, not the machine.

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  Prototype and enclosure6061-T6 aluminium, anodized.
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  Corrosion and hygiene316L stainless, electropolished or passivated.
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  High strength, tight tolerance17-4PH or 7075, heat treated after machining.
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  Weight criticalMagnesium AZ91D, with chip fire controls.

Finishing changes dimensions, so it has to be planned before machining. Anodizing adds a few micrometres of oxide per surface, which is fine on a cosmetic cover and a problem on a press-fit bore. Hardcoat anodizing builds more and can round a sharp edge; if the edge must stay sharp, mask it or machine it after coating. Electroless nickel, zinc, silver and gold plating follow the same rule. Powder coating and black oxide are the two finishes least likely to move a tolerance, because the build is thin and predictable.

Bead blasting, tumbling, brushing and polishing are mechanical. They remove material, sometimes unevenly on a soft alloy, so we set them after the final dimensional check on critical features. Laser marking and engraving need a minimum character height of 1.5 mm to stay legible after coating. If your part number must survive anodizing, tell us at quote time rather than after the parts are finished.

Inspection runs through the whole job. Raw material is checked on arrival, dimensions are monitored in process, and 100% of parts are inspected before shipment. Reports are available on request. The historical qualification rate is 99.99%, which reflects a lot of small decisions: correct stock size, correct cutter, correct coolant, and a fixturing plan that does not let the part move.

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  AnodizingClear, colour, hardcoat, conductive; plan the build.
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  PlatingElectroless nickel, zinc, silver, gold.
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  Mechanical finishBead blast, tumble, brush, polish.
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  MarkingLaser, minimum character height 1.5 mm.

CNC machining is subtractive, so cost tracks removed volume. A part that starts as a 200 mm block and ends as a 20 mm bracket wastes most of the material and most of the cycle time. If you are making more than a few hundred identical brackets, die casting or sheet metal fabrication will beat machining on unit cost. If the geometry is organic and the surface only needs to look right rather than seal, 3D printing may be enough. Vacuum casting is a better route for short runs in a rubber-like or transparent resin.

There are also hard limits inside the process. A pocket deeper than about four times its width needs a long tool, and a long tool deflects. Corners tighter than the cutter radius cannot be cut square; a Ø6 mm end mill leaves a Ø3 mm corner radius. A thread smaller than M2 is possible but fragile, and a slot narrower than 1 mm in stainless will break small cutters often enough to affect delivery. None of these are refusals. They are the points where we come back with a design change instead of a price.

Confidentiality is handled the same way for every job. Uploads are secure and confidential, and an NDA is available on request before you send a model. That matters most on pre-launch products, where the drawing is the only thing that exists.

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  High volume, simple shapeDie casting or sheet metal costs less per part.
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  Organic shape, cosmetic only3D printing may be sufficient.
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  Deep pocketPast 4:1 depth-to-width, deflection grows.
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  Sharp internal cornerLimited by the cutter radius, not the machine.