There are mainly two distinct classes of solid-state manufacturing processes.
Deformation processes produce the required shape, with the necessary
mechanical properties, by plastic deformation in which the material is moved and
its volume is conserved. Machining processes produce the required shape by
removal of selected areas of the workpiece through a machining process. Most
machining is accomplished by straining a local region of the workpiece by the
relative motion of the tool and the workpiece. Although mechanical energy is the
usual input to most machining processes, some of the newer metal removal
processes employ chemical, electrical and thermal energy. Machining is usually
employed to produce shapes with high dimensional tolerance, good surface finish
and often with complex geometry. Machining is a secondary processing operation
since it is usually conducted on a workpiece that was produced by a primary