Modern Machining Processes:
In the past two decades some ultra hard and difficult to process of metals and alloys are not easy to manufacture, but continuous research on this field will produce rapid growth in this modern machining technology. The concept of material removal by Conventional edged tool machining is uneconomical for such harder and difficult to manufacturing materials and the degree of accuracy and surface finish attainable is poor. These edged tools machining involving plastic deformation and formation of chips has been known to man for several hundred years. The higher strength level would have a disastrous effect on the total machining bill if there was no corresponding improvement in machining technology. In view of the significance of this problem, Merchant (1960) highlighted the need for the development of newer concepts in metal machining; By adopting a integrated plan and utilizing the results of basic and applied research, it has now become possible to process some of the materials which were formerly considered to be unmachinable under normal conditions. Some of these methods have been commercially exploited while others are still in their experimental stages. The so developed newer machining processes are often called as “modern machining processes” or “unconventional machining processes”. The name unconventional implies that conventional tools are not engaged for metal cutting; rather energy is utilized in its direct form.
Modern machining processes are classified according to the type of fundamental machining energy employed, such as mechanical, electrochemical, chemical or thermoelectric.
Classification of Unconventional Machining Processes
Type of Energy
Metal Removal Mechanisms involved
Modern Manufacturing Process
High velocity particles
Abrasive Jet Machining (AJM), Ultra Sonic Machining (USM), Water Jet Machining (WJM)
Electro Chemical Machining (ECM), Electro Chemical Grinding (ECG)
Chemical Machining (CHM)
Hot gases Electrons
Ionized material High voltage
Ion Beam Machining (IBM), Plasma Arc Machining (PAM), Electro Discharge Machining (EDM)
Laser Beam Machining (LBM)
Plasma Arc Machining (PAM)
To make effective utilization of advanced machining methods, it is important to know the precise character of the machining issue. It is to be comprehended that:
(i) these methods cannot replace the conventional machining processes and
(ii) a particular machining method found suitable under the given conditions may not be equally efficient under different conditions.
A careful assortment of the procedure for a given machining issue is fundamental.
Before selecting the process to be employed, the following aspects must be studied:
(i) Physical parameters.
(ii) Properties of the work material and the shape to be machined.
(iii) Process capability.
(iv) Economic considerations.
When comparing the physical parameters of modern machining processes, it may be noticed that both EDM and USM require approximately the same power, whereas ECM consumes roughly forty times more power than EDM. ECM consumes much greater power, it is an excellent method for drilling long slender holes with length/dia ratio > 20. It can be seen that for the machining of electrically non-conducting materials, both ECM and EDM are unsuitable, whereas the mechanical methods can achieve the desired results.