Plunge milling lets you roughly machine deep cavities by a series of overlapping plunges into the material. The tool makes its first plunge into the material along a predrilled axis, parallel to the Z-axis of the NC Sequence coordinate system, then retracts to the level specified by CLEAR_DISTANCE, moves over in the XY-plane and makes the next plunge. Distance between the successive plunges is controlled by the PLUNGE_STEP parameter.

You can use flat and radius end mills, as well as plunge milling tools, to create Plunge milling NC sequences.