ALNO CNC machining explained

At its core, CNC machining is subtractive: a rotating cutter follows a pre-programmed path and removes material from a solid block. Three axes cover most flat work. The X, Y and Z travels reach every face that faces the spindle, but nothing more. Angled holes, undercuts and deep cavities usually mean the part has to be flipped and re-datumed.

Multi-axis machines add rotation. A trunnion table tilts the part while the spindle stays vertical, or a swivel head tilts the tool. With five axes moving at once, the cutter can reach a compound angle in one setup. That is the whole point. Fewer setups mean fewer datum shifts, and each shift is where tolerance stacks up.

So when engineers ask for an explanation of this capability, the honest answer is not about a brand of machine. It is about degrees of freedom and how many times you touch the part. A part that needs four sides machined is a five-axis job. A flat bracket with two holes is not.

The payoff shows up in two places: position tolerance between features, and surface finish on swept or contoured faces. A ball-nose cutter held at a fixed lead angle leaves a consistent scallop height. On a three-axis machine the same surface often needs hand blending afterward.

Five-axis pays for itself when a feature is unreachable in three setups, when two bores must stay coaxial, or when a contoured surface has a tight finish callout. Impellers, turbine housings, medical instrument bodies, and EV motor housings all fall into that group. So do parts with a deep pocket whose floor meets a drafted wall at an angle.

It is the wrong call for simple prismatic work. A plate with a bolt pattern, a shaft with a keyway, a bushing. Those run faster and cheaper on a 3-axis mill or a lathe, and a shop that pushes five-axis time onto them is not helping you. Setup count, not machine glamour, drives unit cost.

There is a middle ground. A 3+2 setup indexes the table to a fixed angle, locks it, then cuts. You get the reach of five axes without simultaneous motion, and the programming is simpler. For a part with four distinct faces and no free-form surfaces, 3+2 is often the most economical route.

One more check before you commit: wall thickness. Thin walls deflect under cutting force no matter how many axes you have. If a wall is under 1 mm and unsupported, plan for light passes, a fixture that backs it up, or a redesign. No machine removes that physics.

• 1
  Good fitCompound angles, coaxial bores, contoured surfaces, features on four or more faces.
• 2
  Poor fitFlat plates, simple shafts, single-face work. Use 3-axis or turning instead.
• 3
  Middle ground3+2 indexed setups for multi-face parts without free-form geometry.

Rotation introduces error sources that a fixed setup does not have. Rotary axis backlash, thermal drift in the trunnion, and probe error all stack. That is why a shop has to verify position after the part is indexed, not just at the end. In-process probing between operations catches drift before the finish pass.

GreatLight works to ±0.005 mm (±0.0002 in) on qualified features, measured on a CMM with reported results on request. As-machined surfaces sit around Ra 1.6–3.2 μm. A fine finish of Ra 0.2–0.8 μm is achievable, but it costs cycle time, so reserve it for sealing faces and bearing bores.

Material matters here too. Aluminum 6061 and 7075 cut cleanly and hold a mirror finish with the right tool path. Stainless 316L work-hardens, so a dwell in the cut ruins the next pass. Titanium Ti-6Al-4V needs low surface speed and plenty of coolant. Inconel is the slowest of the group and the most likely to move after machining.

For thin or asymmetric parts, rough, stress-relieve, then finish. Skipping the relief step is the most common reason a part measures in tolerance at the machine and out of tolerance a day later. If your drawing has a flatness callout over a large face, say so up front.

Ask for the setup plan, not just a price. A quote that says 'five-axis' without saying how many setups hides where the cost sits. A good shop will tell you which faces are machined in which operation and where the datums are. That is also your first look at whether they understood the part.

Check the capacity behind the claim. GreatLight runs 127 high-precision CNC machines, including 16 simultaneous 5-axis centers, 12 four-axis mills, 27 three-axis machines, and 16 mill-turn centers. Maximum processing size is 4,000 mm, with a Ø400 mm rotary table for round work. Ranges like 750 × 1,150 × 550 mm and 500 × 500 × 450 mm cover most parts we see.

Ask about inspection and paperwork. 100% inspection before shipment, with raw material checks, in-process monitoring, and final inspection, plus reports on request. For regulated work, the certifications that matter are ISO 9001:2015, IATF 16949:2016, ISO 13485:2016, and ISO 27001:2022. Match them to your industry before you place the order.

Finally, confirm material and finish availability. If your part calls for 17-4PH and a hardcoat anodize, both need to be in the quote. Getting that confirmed late is how schedules slip. Uploads stay confidential, and an NDA is available on request.