Non traditional machining processes

Advance Manufacturing Processes

1. Non Traditional Machining Processes By Mr. Ashish Umarkar Advanced Manufacturing Processes ( AMP-12154) Unit no:-1 Marks:- 30

2. Development Development of harder and difficult to machine materials such as hastalloy , nitra alloy, waspalloy , nimonics , carbides, stainless steel, heat resisting steels and many other HSTR alloys Used in aerospace industry, nuclear engineering and other industries owing to their high strength to weight ratio, hardness and heat resisting quality.

3. CHIPS FORMATION IN CONVENTIONAL MACHINING PROCESS Thus the major characteristics of conventional machining are: • Generally macroscopic chip formation by shear deformation • Material removal takes place due to application of cutting forces – energy domain can be classified as mechanical • Cutting tool is harder than work piece at room temperature as well as under machining conditions TOOL WORKPIECE CHIP TOOL WORKPIECE CHIP

4. Schematic representation of various metal cutting operations .

5. The broad classification is given as follows: Thus classification of NTM processes is carried out depending on the nature of energy used for material removal. Mechanical Processes ⎯ Abrasive Jet Machining (AJM) ⎯ Ultrasonic Machining (USM) ⎯ Abrasive Water Jet Machining (AWJM) Electrochemical Processes ⎯ Electrochemical Machining (ECM) ⎯ Electro Chemical Grinding (ECG) ⎯ Electro Jet Drilling (EJD)

6. • Electro-Thermal Processes ⎯ Electro-discharge machining (EDM) ⎯ Laser Beam Machining (LBM) ⎯ Electron Beam Machining (EBM) • Chemical Processes ⎯ Chemical Milling (CHM) ⎯ Photochemical Milling (PCM) etc.

7. Abrasive Jet Machining (AJM) ¼ turn valve Electro-magnetic shaker Mixing chamber exhaust Nozzle work piece Abrasive feeder Pressure control valve Air compressor Drier filter

8. Ultrasonic Machining (USM)

9. ELECTROCHEMICAL MACHINING (ECM)

10. Electrolyte An  electrolyte  is any substance containing free  ions  that make the substance  electrically conductive . The most typical electrolyte is an  ionic solution , but molten electrolytes and  solid electrolytes  are also possible. Function of electrolyte- Carrying current between tool and work peice Remove products of machining and other insoluble products from cutting region Dissipate heat produced in the operation.

11. Characteristics of Electrolyte Good electrical conductivity Non toxicity and chemical stability Non corrosive property Low viscosity and high specific heat Electrolyte used- Sodium chloride

12. Electric Discharge Machining (EDM)

13. Wire-cut EDM (WEDM)

14. Dielectric Fluid A  dielectric  is an electrical  insulator  that can be  ionized  by an applied  electric field . When a dielectric is placed in an electric field, electric charges do not flow through the material as they do in a  conductor , but only slightly shift from their average equilibrium positions causing  dielectric polarization . Characteristic- Low viscosity High fluidity Controlled level of toxicity Cheap and easily available

15. Function of Dielectric Fluid Insulation Until required breakdown voltage attained. Should act as conductor after required breakdown voltage attained. Should demonize rapidly after the discharge has been occurred. Clean spark gap by carrying away the molten metal. Should cool the tool work piece and spark region. Dielectric Used:- light hydro carbon oil, kerosene, paraffin, transformer oil, try ethylene glycol.

16. LASER Beam Machining (LBM)

17. Electron Beam Machining (EBM)

18. Chemical Machining (CHM)

19. PAM

20. Difference between EDM & ECM Uses dielectric fluid as a conducting medium between tool and work piece. Wear of tool takes place during the process. Heat is generated during the process. Low metal removal rate. It works on the principle of spark erosion. Metal is removed by melting and vaporization. Tools used are oversize for machining inside surfaces and undersize for machining outside surfaces. Using electrolyte as a conducting medium between tool and work piece. No wear of tool during process so tool life is high. No heat is generated during the process. Metal removal rate is high. It works on principle of Faraday’s law of electrolysis. Metal is removed by electrochemical reaction. Tool used are of required size of the work piece .

21. Dielectric Electrolyte It is used as conducting medium in EDM process. It act as conductor and insulator both. Tool wear takes place in the dielectric fluid. It may or may not be corrosive in nature. It used as conducting medium in ECM process. It always provide passage for supply of electricity. The electrolyte selected is such that there is no wear of tool. It should be non corrosive in nature.

22. EBM LBM When high velocity electrons strikes the work piece its kinetic energy converted into heat energy. Electron gun is used as a tool. Accuracy is good. Metal removal rate is low. The complete process should kept in vacuum. Usually only metals. When excited atoms releases photons in the form of chain, a LASER beam is generated which strikes on w/p & melts it. LASER material is used as tool. Accuracy is comparatively more. Metal removal rate is high. Vacuum is required between flash lamp and ruby rod. Any material but not only suitable for plastic.

23. Questions Which of the following process uses mechanical energy as principle energy source ECG LBM Conventional milling USM WJM WEDM

24. 2. Chemical milling is used in which of the following application Drilling holes with high depth. Making intricate patterns on thin sheet metal Removing material to make shallow pockets in metal. Removing metals from aircrafts wing panels. Cutting of plastic sheets.

25. 3. Which of the following process would be best suited for cutting a hole of 0.003 inch dia ? AJM CHM EDM LBM WEDM

26. 4. Ultra sonic machining can be used for both metallic and non metallic materials? True False

27. 5. Which of the following process could be used to cut a large piece of 1/2inch thick? AJM CHM EDM LBM WEDM