1. New material with low machinability
2. Dimensional and accuracy requirements.
3. A higher production rate an economy.
Many new material alloys that have been developed for specific uses possess a very low machinability. Producing complicated geometries in such materials becomes extremely difficult with the traditional methods .Also some times the combination of the material properties and the job dimensions is such that the use of the traditional processes becomes impossibles. Examples of this types of jobs are machining a complicated turbine blade made of supper alloy, and producing wholes and slots in material such as glass and semiconductor. At times the job become difficult because of the dimensional complication. so drilling a non circular hole or micro hole becomes problematic if the traditional processes are used.
Difference between conventional and unconventional machining