Uniteam CNC machining

• 1
  What the Uniteam platform actually is
• 2
  Why one setup changes the cost of the part
• 3
  Materials that suit a gantry, and the ones that fight it
• 4
  What ±0.005 mm means on a 3 m part
• 5
  Where a gantry loses to a small vertical
• 6
  Gantry vs compact vertical: which platform fits

Uniteam builds gantry machining centers: the workpiece sits on a fixed bed, and a bridge carrying the spindle travels over it. That is the opposite of a C-frame vertical mill, where the table moves under a fixed column. Once the table stops moving, the part stops moving with it. Mass stays still, so a 3 m airframe rib does not have to be accelerated and stopped thousands of times per hour.

The second consequence is reach. A gantry with a 4,000 mm X travel, a 400 mm Y and a 150 mm Z can machine a long extrusion, a battery tray rail or a wing spar in one setup. A 40-taper vertical with a 750 mm table simply cannot hold the part, no matter how good the toolpath is.

The trade is stiffness per unit of travel. A gantry bridge spans a wide gap, so it deflects more under a given cutting force than a compact C-frame. That deflection shows up as chatter on thin walls and as a slower safe feed rate. If your part is 200 mm cube, a gantry is the wrong tool. If it is 2,500 mm long with a 0.8 mm wall, it is the only tool.

GreatLight runs 16 simultaneous 5-axis centers among 127 high-precision CNC machines, with a 4,000 mm maximum processing size and a Ø400 mm rotary table for the shorter parts. We quote gantry work and small-batch turning on the same line, so you are not passed between shops.

Every time a long part moves to a second machine, you pay twice: once for the move, and again for the re-datum. Aligning a 3 m extrusion to ±0.05 mm on a second fixture can eat an hour before a single chip is cut. On a gantry, the five axes reach five faces from one datum, so position errors stay inside one stack-up instead of accumulating across two.

That single datum matters more on parts with tight hole-to-hole position. If a row of 40 holes along a spar has to sit within ±0.005 mm of the first hole, splitting the job across two machines almost guarantees a fight with the tolerance. Keeping it on one gantry keeps the error budget in one place.

Fixturing on a gantry is mostly about support, not clamping force. Long thin parts sag under their own weight, and a vacuum or magnetic bed with adjustable supports lets you shim the part to a known plane before locking it. Probing the top face after clamping tells you the real number, not the assumption.

The counterpoint: setup on a gantry takes longer than on a small vertical. If you are running 500 small brackets, that setup time per part is a rounding error. If you are running 5 long rails, it can be 30% of the job. Ask which one you are buying before comparing hourly rates.

Aluminum is the natural fit. 6061-T6, 7075 and 2024 cut fast at high spindle speed, and the light cutting force keeps bridge deflection small. A long 6061 rail with a thin web machines cleanly at 8,000–15,000 rpm with high-feed tooling and good chip evacuation.

Titanium and Inconel are the difficult end. Ti-6Al-4V (TC4) and Inconel push cutting forces up and heat into the edge, so a gantry has to slow down and take lighter passes. That is workable for a prototype or a short run, but on a 2 m Inconel part the cycle time stacks up fast, and tool wear along a long path becomes the cost driver.

Magnesium AZ31B and AZ91D cut easily, but the chips burn. Any gantry running magnesium needs dry or minimum-quantity lubrication, a chip collection plan and a fire procedure. Not every shop will take that job, and the ones that do often charge for the handling.

Plastics and composites are a mixed case. PEEK and carbon fibre machine fine with the right tool geometry, but dust extraction and tool wear on abrasive carbon are the real limits. For long carbon parts, ask about extraction before you ask about tolerance.

Across all of these, 100% inspection before shipment is standard at GreatLight: raw material check, in-process monitoring and final inspection, with reports on request.

A tolerance is only meaningful over a stated length. ±0.005 mm is achievable on a feature a few hundred millimetres long, on a machine in thermal equilibrium, with a warm shop and a sharp tool. Over 3,000 mm, the same number runs into thermal growth: aluminum expands about 23 µm per metre per degree Celsius. A 3 °C shop swing moves a 3 m aluminum part by roughly 0.2 mm.

So the honest spec on long parts is usually a tighter local tolerance plus a looser overall one. Hole positions and mating features get ±0.005 mm; overall length and non-critical profiles get something a gantry can actually hold. Write that into the drawing and you get a part that passes, not a part that argues.

Surface finish follows the same logic. Ra 0.2–0.8 μm is realistic on a small sealing face that a tool can reach at speed. On a long wall, Ra 0.8–1.6 μm is the practical target, and Ra 1.6–3.2 μm is normal as-machined. Chasing a mirror finish down a 2 m wall adds polishing time that rarely pays back.

For inspection, a coordinate measuring machine large enough to hold the part is the constraint. Long parts often get measured in sections with an overlap, and the report should say so. If a supplier claims a full-length CMM report on a 3 m part, ask which machine produced it.

Small, high-volume parts lose on a gantry. A 60 mm bracket run at 10,000 pieces needs fast tool changes, short rapids and cheap setup, and a compact vertical or a mill-turn center does that better. Gantry travel is wasted motion on a part that fits in your hand.

Deep single-axis drilling and tapping also favor a dedicated machine. A gantry can do it, but a drill-tap center cycles faster and holds thread position without the long reach. If 70% of the cycle is holes, the gantry is the expensive way to make them.

Very tight roundness and concentricity on turned features belong on a lathe or mill-turn platform. GreatLight runs 16 mill-turn centers for exactly that reason: one machine turns the diameter and mills the flats without a second datum.

The rule we use: if the part fits inside 500 × 500 × 450 mm and ships in volume, quote it on a compact machine. If it is longer than about 1,200 mm, or if it has features on five faces that must share one datum, put it on a gantry. Everything between those two is a judgement call and usually comes down to how many parts you need.