The term "5-axis" refers to the number of directions in which the cutting tool can move. On a 5-axis machining center, the cutting tool moves across the X, Y and Z linear axes as well as rotates on the A and B axes to approach the workpiece from any direction.

In the simplest terms, 5-axis machining involves using a CNC to move a part or cutting tool along five different axes simultaneously. This enables the machining of very complex parts, which is why 5-axis is especially popular for aerospace, opto-mechanical and medical applications.

However, several factors have contributed to the wider adoption of 5-axis machining. These include:
1 - A push toward single-setup machining (sometimes referred to as "Done-in-One") to reduce lead time and increase efficiency
2 - The ability to avoid collision with the tool holder by tilting the cutting tool or the table, which also allows better access to part geometry
3 - Improved tool life and cycle time as a result of tilting the tool/table to maintain optimum cutting position and constant chip load