3 Axis CNC Machining Services

On a three-axis mill the cutter travels in X, Y and Z while the spindle stays vertical. The tool reaches any point inside the work envelope, but every cut is normal to the spindle axis. Undercuts, deep side pockets and features on the back face need a second setup, a fixture that tilts the part, or a different machine.

Three-axis work is the base of most machining shops, ours included. We run 27 three-axis machines alongside 12 four-axis mills and 16 simultaneous 5-axis centers. The three-axis group handles flat plates, brackets, housings, manifolds, jigs and any prismatic part whose features lie on accessible faces.

A three-axis setup is the fastest to program and the easiest to inspect. Tool paths are simple. Setup is repeatable. When a part fits this envelope, choosing a 5-axis machine adds cost without adding much.

Parts with planar faces, through holes, counterbores, tapped holes, slots and pockets all sit comfortably on three axes. So do parts with loose tolerances on the back side, or parts you can flip once with a simple vise stop.

The decision usually turns on two questions. How many distinct faces carry features, and how tight must those features stay to each other? If the answer is one or two faces, and the cross-face tolerance is looser than ±0.02 mm, three-axis is the economical choice. If four or more faces carry tight features, repositioning error starts to dominate.

Deep cavities with a small corner radius are a poor match. A short three-axis tool cannot reach the bottom without a long, thin end mill that deflects. That is a geometry problem, not a machine problem.

Thin walls below roughly 1 mm are also awkward. Clamping force, cutting force and springback all push the wall around. Here a fixture change, a gentler stepover, or a four-axis approach from the side usually works better.

Our three-axis group holds ±0.005 mm (±0.0002 in) on critical dimensions under controlled conditions. That number assumes a rigid setup, a sharp tool and a stable material. Aluminum 6061 and 7075 hold it more easily than thin-wall Inconel.

As-machined finish lands around Ra 1.6–3.2 μm. With a finishing pass and the right insert, Ra 0.8–1.6 μm is routine. Below Ra 0.2 μm we move to a polishing or lapping operation rather than chasing it on the mill.

All the usual materials run on three axes: 6061 and 7075 aluminum, 303 and 316 stainless, 1018 and 4140 steel, C360 brass, POM and PEEK. Plastics cut fast but move with heat, so we keep coolant and feed under control to hold size.

Every part goes through 100% inspection before shipment, with raw material checks, in-process monitoring and a final report available on request.

The real risk in three-axis machining is the flip. Once the part leaves the vise, you have a new datum, a new clamp load and a fresh chance to lose alignment. A soft jaw cut to the part profile, a stop pin, or a dedicated plate with dowel pins fixes most of it.

For runs above a few dozen pieces we build a fixture that locates on a machined feature rather than on the raw stock. That single change often holds cross-face position to ±0.01 mm without touching the machine.

Where a part needs a third face machined and volume is low, a tilting vise or an angle plate beats a 5-axis quote. The setup takes longer, but the tool path stays simple and the inspection stays straightforward.

We can design and cut these fixtures in-house. Send the drawing and we will tell you where the setup risk sits before the job starts.

Move up when the part has features on four or more faces, when compound angles must be cut in one pass, or when a contoured surface needs to be followed with a short tool. Those cases spend more time in repositioning than in cutting on three axes.

A four-axis machine adds a rotary table, usually Ø400 mm on our floor. That lets the part index around a single axis, so a shaft with cross holes or a cylinder with radial slots is cut without a second setup. It is the cheapest step up from three axes.

Five-axis simultaneous motion suits impellers, medical implants and complex aerospace housings. We keep 16 such centers for that work. If your part is flat and prismatic, though, three-axis will quote lower and ship faster.

No minimum order quantity applies here. One prototype or a 10,000-piece run both run through the same inspection routine.