5-axis machining means machining on a machine that combines the three usual linear axes (X, Y, Z) with two rotary axes, for example A and B or B and C. The tool can therefore approach the part at almost any angle without it being unclamped.
Two modes must be distinguished. In 3+2 machining, or “indexed”, the rotary axes orient the part, then machining proceeds as on a three-axis machine: ideal for machining several faces in a single clamping. In simultaneous (continuous) 5-axis machining, all five axes move together, which allows freeform surfaces to be followed while keeping the tool at its optimum orientation. The machine has a tilting rotary table or a swivelling head. This kinematics requires CAM software able to calculate the toolpaths and avoid collisions, as well as a simulation of the path before the first part.
The advantages are fewer re-clampings, and so better positional accuracy between faces, shorter and stiffer tools, and so better surface finishes, and access to undercuts. Typical parts are blades, turbines and propellers, implants, moulds, complex housings and any shape with freeform surfaces. For a simple prismatic part, three axes are enough, and standard milling remains the cheapest. The 5-axis machining guide compares use cases, and the CNC machining page describes the usual services.
In a quote request. Supply the 3D model (STEP file), which is essential for programming, and flag angled faces, oblique holes and undercuts. Give the overall dimensions and the position tolerances between faces. Let the workshop choose between 3+2 and simultaneous 5-axis: the right mode depends on the part and the cost.