In CNC milling machines, the fourth axis refers to the additional rotational axis beyond the typical three linear axes (X, Y, and Z). This extra axis enables the cutting tool to rotate around a different axis, allowing for more complex machining operations.
Most common types of fourth axes
Rotary Table: This axis allows the workpiece to rotate around a vertical or horizontal axis. It's useful for machining cylindrical or circular features on a workpiece.
Indexing Head: Similar to a rotary table, an indexing head can rotate the workpiece to precise angles, enabling milling operations at specific angular intervals.
Rotary Fixture: This axis enables the rotation of the workpiece around an axis perpendicular to the main three linear axes. It's often used for machining features on multiple sides of a workpiece without the need for repositioning.
Articulated/Continuous Rotation Axis: This axis allows for continuous rotation of the cutting tool or the workpiece, providing more flexibility for machining complex geometries, such as helical shapes or curved surfaces.
