During any End Milling operation it is important that the metal removal rate (chip thickness), is not too light.  The chip thickness is affected by the Radial Depth of Cut (RDOC).  The smaller the Depth-of-Cut, the smaller the chip thickness will be unless the table feed  (ipm) is increased

If the Radial Depth-of-Cut is less than half the End Mill diameter the feed per tooth should be increased to increase the chip thickness. For radial depths of cut greater than half the end mill diameter, the lower range of recommended feed-per-tooth from "Speed & Feeds Recommendations" , should be used.

The table below gives the approximate values of how much the feed-per- tooth should be increased for various percentages of End Mill diameter engagement.