Unconventional Machining Process is defined as a group of processes that remove excess (stock) material from work piece by various techniques involving Mechanical, Thermal, Electrical and chemical energy or combination of these energies but do not use a sharp cutting tools as it needs to be used for traditional machining processes. Extremely hard and brittle materials are difficult to machine by the following traditional machining processes Viz; Milling, Turning, Drilling, and Shaping. Unconventional machining process, also called advanced machining processes or advanced manufacturing process, are employed where traditional machining are not feasible, satisfactory and economical due to various factors are listed below.
1. Fragile & Hard materials are difficult to clamp in traditional machining. If such kinds of materials are machined with the help of conventional machining processes, either the tool undergoes extreme wear (while machining hard work piece) or the work piece material is damaged (while machining brittle work piece).
2. When the shape of the part is too complex. Large cutting forces are involved and material is removed in the form of chips. Sometimes enormous heat is produced in the work material which results formation of residual stresses. Due to this action reduces the life and quality of the finished product.
3. If the work piece is too flexible or slender (L/D ratio), then conventional Machining process produces work piece with poor quality with poor surface finish.
All this drawbacks were overcome by using unconventional machining processes to attain good dimensional accuracy, improved surface finish, optimizing the process,cost reduce and quality of the product is maintained.
Many types of Unconventional Machining Process have been developed to meet various required machining conditions. When these processes are implement properly, they offer many advantages over Traditional machining processes. The common Unconventional machining process are described below.
i. Mechanical Energy based Unconventional Machining Processes (E.g. Abrasive Jet Machining, Water Jet Machining, Abrasive Water Jet Machining, Ultrasonic Machining, Ice Jet Machining, Magnetic Abrasive Finishing)
ii. Electrical Energy based Unconventional Machining Processes (E.g. Electrical Discharge Machining, Wire Cut Electrical Discharge Machining)
iii. Electro Chemical Energy based Unconventional Machining Processes (E.g. Electro chemical Grinding, Electro Chemical Drilling, Shaped tube Electrolytic Machining, Electro Stream Drilling, Electro Chemical Jet Drilling, Electro Chemical Deburring)
iv. Chemical Energy based Unconventional Machining Processes (E.g. Chemical Milling, Photo Chemical Milling, Electro Polishing)
v. Thermal (or Electro-thermal) Energy based Unconventional Machining Processes (E.g. Plasma Arc Machining, Laser Beam Machining, Electron Beam Machining, Ion Beam Machining )
vi. Material Addition Process: ( E.g. Liquid based techniques, Powder based techniques, Solid based techniques)
2. Based on the source of energy
ii. Hydraulic Pressure
iii. Ionized Particles
v. Pneumatic Pressure
vii. Magnetic field
viii. Ultrasonic vibrations
3. Based on the medium of energy transfer
ii. Chemical reagent
vii. Pressurized gas
xi. Ultrasonic waves
4. Based on the mechanism of material removal
ii. Chemical Etching
iv. Electric Discharge
v. Ion Displacement