• PAM:-













     :-     Plasma Arc Machining Process is an unconventional are non traditional machining process. When the gas is heated above 5500°c , then they are partially ionised and exit in the from of a mixture of  free electron , positive charge ion and neutral ion . This mixture is called as plasma . The temperature of central part of plasma gas is 11000°c to 28000°c where the gas is completely ionised . In plasma Arc machining a high velocity jet of this high temperature ionised gas is directed to the workpiece surface by means of plasma Arc cutting torch . The jet malts the metal of the workpiece and displaces the molten metal from its path . A heating of workpiece is not due to any Chemical reaction but an account of the continuous attack of electrode which transfer heat energy of high temperature ionised gas towards the workpiece . It is used for any material including , which can be subjected to chemical reaction . Chouse of gas mixture for the use these purpose depends on the material to cut . It should be economic. Here any gas or gas mixture which doesn't affect the electrode or the workpiece can be used safely. Generally the gas mixture are depends upon , which material to be cut . Nitrogen , Nitrogen - Hydrogen ,  argon - hydrogen gas mixture ( plasma ) are to be cut aluminum and magnesium material . 




Working Principle :- 




                      

                  :-    The plasma Arc cutting torch carries tungsten electrode fitted in a small chamber . The electrode is connected to the negative terminal of DC supply and the workpiece and nozzle is connected to the positive terminal . A strong Arc is formed between the electrode and nozzle and the gas mixture is forced in to the chamber . As the gas molecule is collite with the high velocity of electron of the arc , they get ionised and very large amount of heat is generated . The flow of gas is so controlled that they are remain stable . The high velocity of stream or hot ionised gas is called plasma .






Advantages :- 


   

   

                    1 :- This is a faster process .
                    2 :- High temperature is generated for metal removal .
                    3 :- This process can be used to cut any material . 






Disadvantages :- 

   

                          1 :- Initial cost is very high be.
                          2 :- Uneconomical for bigger cavities to be machined .
                          3 :- Inert gas consumption is high .