The conventional metal cutting processes make use of the shearing process as the basis for material removal. However, non-traditional processes depend on a number of other factors such as the vaporization of the metal, electrolytic displacement, chemical reaction and mechanical erosion. The main reasons for using non-traditional machining processes are high strength alloys, complex surfaces and higher accuracies and surface finish.

   High strength alloy The hardness of the work material is often higher than the cuttiong tool material and sometimes it becomes unnecessary to use the machining process on hardened material. In such cases the electro-chemical processes would be required.

   Complex surfaces, There are times when very complex surfaces in three dimensions need to be produced, such as those in moulds and dies where the workpiece surface being the hardened tool steel would be difficult to be processed by conventional means.

   Higher accuracies and surface finish, The accuracy and surface finish desired in hard workpiece materials can not be obtained through conventional machining as it is done at a very slow pace, make it uneconomical.

   In addition to the complex geometries,sometimes it is required to produce difficult geometries such as long holes with length to diameter ratio approaching that of 100, or very small size holes suach as those with less than 0.1mm in diameter which are almost impossible to be produced by conventional methods.