For example, if the Feed % attribute is 2000 MMPM and you set the Plunge feed % to 50, and the First plunge feed % to 20, the resulting feed rate for the first plunge move is 200 MMPM. Setting the First plunge feed % at a slower feed rate can protect your tool from a hardened crust on the surface of the material.
Plunge clearance
Z ramp clearance
First Z depth
First plunge move