Five-axis machining

Five-axis machining is milling in which two rotary axes move alongside the three linear axes. That lets the tool reach a face at an angle and lets several sides of a part be machined without re-clamping it. There are two forms: 3+2, where the rotary axes are locked during the cut and only position the part, and continuous five-axis, where they move during the cut.

What it means for the calculation

The gain sits in the setups, not in the cut. A part that takes four setups in three axes often takes one or two in five. That saves setup time, alignment error and lead time. Against that, the machine rate is higher and programming takes longer. On a single piece the saved setup time weighs heavily; on a large batch, three-axis work on a cheaper machine can be the better deal. Continuous five-axis also needs more programming and proving time than 3+2.

Where it appears on the drawing

Never as a word. It follows from the shape: angled faces, holes at an angle, undercuts, and geometric tolerances that tie sides to each other all point to five-axis work.

Common mistakes

Assuming a five-axis machine always works out cheaper because there are fewer setups, without counting the higher rate and the longer programming time. Also mixing up 3+2 and continuous five-axis: those need different programming and proving times.

Is 3+2 also five-axis?

Yes, but the two rotary axes are locked during the cut; they only position the part.

Does five-axis make a part more accurate?

Indirectly: fewer setups means fewer alignment errors stacking on each other.

Can any part be made in five axes?

Technically often yes, but on simple, flat parts you then pay for capability that is not used.