In the rough turning , the aim is high removal rate and in the case of fine turning , the final desired tolerance is achieved
Machining of a workpiece is generally divided into one or two levels of roughness. The first level can be for a first pass over a workpiece's uneven surface, which gives rise to varying chips and large cutting forces and strokes..
Thereafter, a more optimized level of rough turning performed to such high removal rate as possible achieve near final shape.
The machining is then completed with a finishing pass which attains the detail's dimensions and tolerances.
The different levels make different demands on the inserts and cutting angles where, for example, negative rake inserts are best suited for coarse machining since they have a better ability to absorb cutting forces which allows higher cutting speeds.With finer machining, positive rake inserts are usually chosen which give a better surface finish but at the expense of removal rate.
Read more under Positive and negative turning inserts as well as Positive and negative milling inserts.
In optimum conditions, the workpiece's original dimensions are so close to the final shape (called near-net-shape) that only finishing is required to complete the detail.