Engineering Resource

When five-axis is the right tool

• Contoured or freeform surfaces that a 3-axis tool cannot reach at the right angle.
• Parts with features on several faces, where fewer set-ups means less stack-up error.
• Deep pockets and undercuts that need the tool tilted into the part.
• Parts whose features must stay in relation to each other, so one set-up is worth more than a tighter per-feature tolerance.

Simultaneous versus 3+2

3+2 (positional) machining tilts the part to a new orientation and then cuts in three axes; it is faster, simpler and ideal for angled faces. Simultaneous machining moves all five axes at once, which is what allows a tool to follow a contoured surface smoothly. Both are useful, and the right one depends on the surface, not on prestige.

What it changes for tolerance and cost

We hold ±0.005 mm on 3-axis work and ±0.01 mm as standard on simultaneous 5-axis. Five-axis machine time costs more per hour, but it can remove two set-ups, a fixture and the stack-up error between them — which often makes the part cheaper and more consistent overall.

Preparing a part for five-axis

Five-axis rewards good design: features should be reachable without the tool colliding with the fixture, and the part needs faces the fixture can hold without blocking the cut. A DFM review before quoting confirms which features need simultaneous motion and which do not.