There are three factors in any basic turning operation; they are turning speed, depth of cutting and feed rate. Of course, other factors such as kind of material and type of tools have important influence, but these three factors are the ones that operator can change by operating the machine.
Turning speed always refers to the spindle and the workpiece. When it is called as round per minute(RPM), it tells their rotating speed. But the important figure for a particular turning operation is the surface speed, or the speed at which the workpiece material is moving past the cutting tool. It is simply the product of the rotating speed times the circumference (in feet) of the workpiece before the cut is started. It is expressed in surface feet per minute, and it refers only to the workpiece. Every different diameter on a workpiece will have a different cutting speed, even though the rotating speed remains the same.
Depth of Cutting is practically self explanatory. It is the thickness of the layer being removed from the workpiece or the distance from the uncut surface of the work to the cut surface, expressed in inches. It is important to note, though, that the diameter of the workpiece is reduced by two times the depth of cut because this layer is being removed from both sides of the work.
Feed rate, always refers to the turning tool, and it is the rate at which the tool advances along its cutting path. On most power-fed lathes, the feed rate is directly related to the spindle speed and is expressed in inches (of tool advance) per revolution (of the spindle). The figure, by the way, is usually much less than an inch and is shown as decimal amount