For all metal-cutting processes, "speeds and feeds" are important parameters. The colloquial term "speeds and feeds" refers to the speed, feed, and depth of cut of a metal-cutting process. To describe these parameters, we will be using the turning process. The figure below shows the important geometry. The speed (Labeled on the figure as V.) is the cutting speed, which is a measure of the part cut surface speed relative to the (here, stationary) tool.
Speed is a velocity unit, which is typically listed in terms of feet/min, inches/min, meters/second, or meters/min.
Feed (Labeled on the figure as fr), is the amount of material removed for each revolution or per pass of the tool over the workpiece. Feed is measured in units of length/revolution, length/pass, length/tooth, length/time, or other appropriate unit for the particular process.
The depth of cut, DOC (Labeled on the figure as d.), represents the third parameter for metal cutting. For turning, DOC is the depth that the tool is plunged into the surface. The DOC is half of the difference in the diameters Da and Db,