FEM Modeling Final PPT (final ).pptx for mechanical

Fem

1. FEM MODELING OF ELETRICAL DISCHARGE MACHINING OF SS304-CU IN GAS GUIDED BY  Mr. AJEESH AS ASSISTANT PROFESSOR MECHANICAL ENGINEERING. GROUP MEMBERS  AHMAD SUBAIR JAFAR (MUS20ME005) ALHAM SHAREEF PK (MUS20ME006) ASWIN GS (MUS20ME009) SUHAIL MOHAMMED S(MUS20ME019) 

2. CONTENTS ABSTRACT INTRODUCTION LITERATURE REVIEW  AIM STUDY OF EDM METHODOLOGY MODELLING RESULT CONCLUSIONS  FUTURE WORK  R EFERENCES

3. ABSTRACT Electro discharge machining (EDM) process is a non-conventional and noncontact machining operation which is used in industries for high precision operation EDM in gas uses gaseous dielectric medium instead of a conventional liquid dielectric such as water, kerosene etc. This is an environment friendly technology and has many advantages .   In the present work we have developing a FEM based model for the simulation of gas dielectric EDM of SS304- Cu in Oxygen and Helium .

4. INTRODUCTION Due to the continuous developments in the field of engineering and technology, the scientists and the researchers are facing more and more challenging jobs in these fields of designing and manufacturing. Since 1940, a revolution has been taking place that once again allows manufacturers to meet the demands imposed by increasingly sophisticated designs, but unmachinable . As a result, a new form of manufacturing processes used for material removal, forming, and joining, known as non-conventional manufacturing processes  has introduced .

5. Electric Discharge Machining (EDM) Electro Chemical Machining (ECM) Abrasive Jet Machining (AJM)  Abrasive Water Jet Machining (AWJM)  Water Jet Machining (WJM)  Ultrasonic Machining (USM) Laser Beam Machining (LBM)  NON-CONVENTIONAL METHODS OF MACHINING

6. In this present study we have developed a numerical based finite element model to simulate the process of gas di-electric electro discharge machining in Oxygen and Helium. The model is validated by comparing the simulated results with the existing experimental results. A comparative analysis of EDM performance with respect to the material removal rate of Oxygen and Helium based dielectric process was also carried out

7. LITERATURE REVIEW  Jia Tao, Albert J. Shih, Jun Ni, ”Experimental Study of the Dry and Near-Dry Electrical Discharge Milling Processes”, Journal of Manufacturing Science and Engineering, FEBRUARY 2008, Vol. 130 / 011002-1  investigated the dry and near-dry electrical discharge machining (EDM) milling to achieve a high material removal rate (MRR) and fine surface finish for roughing and finishing operations. They found that Oxygen demonstrated the capability to promote MRR and exothermal oxidation in both the dry and the near-dry EDM.  Nitrogen and helium gases could prevent the electrolysis and yield better surface finish in near-dry EDM. 

8.    Avinash Choudhary, Mohan Kumar Pradhan , ”Finite Element Analysis of Electro Discharge Machining using Ansys”, Proceedings of 1st International Conference on Mechanical Engineering: Emerging Trends for Sustainability  modelled the EDM process with the help of Finite Element Method (FEM) using ANSYS 12.0 software and the effects of most significant machining parameters on the workpiece such as current, voltage and pulse duration was analyzed. The analysis showed the temperature distribution at the end of pulse duration, development of residual stresses after the completion of cooling and the changing nature of compressive stresses to the tensile stresses in various stages of machining process

9.     P. Govindan, Suhas S. Joshi , ”Experimental characterization of material removal in dry electrical discharge drilling “,International Journal of Machine Tools & Manufacture 50 (2010) 431–443 conducted experimental characterization of material removal in dry electrical discharge drilling.  The experiments were performed by controlling pulse off-time so as to maximize the material removal rate (MRR). The main response variables analyzed in this work were MRR, tool wear rate(TWR), oversize and compositional variation across the machined cross-sections.  Statistical analysis of the results show that discharge current(I),gap voltage(V) and rotational speed(N) significantly influence MRR. TWR was found close to zero in most of the experiments. 

10.     S Jithin, Ajinkya Raut, Upendra V Bhandarkar ,” FE Modeling for Single Spark in EDM Considering Plasma Flushing Efficiency,International Journalof Machine Tools 2018, Pages 617-628. presented a finite element simulation of a single spark during electrical discharge machining taking into consideration significant aspects such as temperature dependency of material properties, Gaussian distribution of heat flux, plasma flushing efficiency etc. Finite element simulations showed that the crater radius and crater depth increase with increasing values of operating parameters such as discharge current and pulse on time. The validation of the Finite element model is made against experiments. Due to consideration of these important aspects, this model could give a more accurate prediction of crater profile. 

11. AIM Develop a FEM model for the simulation of gas dielectric EDM process with SS304 workpiece and Cu as electrode  Predict the workpiece material removal rate using the developed model with oxygen as gas dielectric medium  Validate the simulated results of oxygen by comparing with the experimental values.  Conduct a comparative analysis of material removal rate of electrical discharge machining in Oxygen with respect to Helium .  

12. STUDY OF EDM INTRODUCTION  TO ELECTRIC DISCHARGE MEACHINING Electric discharge machining (EDM) process is a non-conventional and non-contact machining operation which is used in industry for high precision products especially in manufacturing industries, aerospace and automotive industries. It is known for machining hard and brittle conductive materials since it can melt any electrically conductive material regardless of its hardness. EDM is a type of thermal machining where the material from the workpiece is removed by the thermal energy created by the electrical spark .

13. Controlled axis  Electrical generator  Control panel  Work table  Dielectric fluid container  BASIC COMPONENTS OF AN EDM SYSTEM

14. ELECTRICAL DISCHARGE MACHINING PROCESS EDM is the thermal erosion process in which metal is removed by a series of electrical discharges between a cutting tool acting as an electrode and a conductive workpiece .   When electrode is brought closer to the work piece, sunk in the dielectric fluid, current is passed to the electrode and the work piece, which generates heat in the form of frequent series of sparks that vaporizes the pieces at the closest point of work piece and electrode. After removing the piece at the closest distance between electrode and work piece, the next spark occurs simultaneously at the next closest point between them and so on. This process results on forming a cavity on the work piece with the shape of the electrode.

15.    During this operation the tool and work piece are suppose to keep a distance between them, known as sparking gap .  ▪ This point of transformation of dielectric fluid from non-conductor to conductor is called " ionization point " A flushing operation is undergoing in order to remove the chips from the work piece

16. Advantages of gas dielectric EDM Environment friendly technology No need for special treatment for disposal of sludge, dielectric waste, filter cartridges, etc. Higher Precision Near-zero tool electrode wear No electrolytic corrosion of work piece  No toxic fumes generated Smaller Heat Affected Zone (HAZ) Narrower discharge gap length

17. METHODOLOGY Identified the limitations of EDM. Studied different possibilities of electric discharge machining and ANSYS modeling. Created 2D model of EDM in ANSYS 19, transient thermal module.  Preprocessing and post-processing are done.  Generated results by conducting various simulations and analyzed the result. The obtained results were validated by pre-existing experimental data.

18. ASSUMPTION The workpiece and tool are axi -symmetric. The workpiece and tool material are homogeneous and isotropic  Heat flux is assumed to be Gaussian distributed. The zone of influence of the spark is assumed to be axi -symmetric in nature.  The analysis is done for only one spark. The material properties of the workpiece are temperature independent  The ambient temperature is room temperature.  The shape of crater is assumed to be a cone Workpiece is selected as stainless steel 304 and Cu tool electrode is selected with Dielectric as Oxygen 

19.     Axisymmetric model for EDM simulation and boundary conditions Proposed Simulation Model 

20. INPUT DATA Sl no.   V(Volts)   I(A)   T off    ( μs )   T off (s)   T on    ( μs )   T on (s)   Spark Radius(mm)   Q(W/m 2 )   1   50   12   22   0.000022   66   0.000066   0.085956245   35439234270   2   50   12   33   0.000033   198   0.000198   0.139383314   13477757109   3   50   12   67   0.000067   603   0.000603   0.227519026   5058290392   4   50   15   22   0.000022   66   0.000066   0.094612548   36563834238   5   50   15   33   0.000033   198   0.000198   0.15342004   13905449342   6   50   15   67   0.000067   603   0.000603   0.250431541   5218806084   7   50   18   22   0.000022   66   0.000066   0.102328516   37509139912   8   50   18   33   0.000033   198   0.000198   0.165931954   14264954859   9   50   18   67   0.000067   603   0.000603   0.270855065   5353730856   10   65   12   22   0.000022   66   0.000066   0.085956245   38392503792   INPUT VALUES FOR OXYGEN DI-ELECTRIC    

21. INPUT VALUES FOR HELIUM DI-ELECTRIC  Sl no.   V(Volts)   I(A)   T off    ( μs )   T off (s)   T on    ( μs )   T on (s)   Spark Radius(mm)   Q(W/m2)   1   50   12   22   0.000022   66   0.000066   0.085956245   35439234270   2   50   12   67   0.000067   603   0.000603   0.227519026   5058290392   3   50   18   22   0.000022   66   0.000066   0.102328516   37509139912   4   50   18   67   0.000067   603   0.000603   0.270855065   5353730856   5   80   12   22   0.000022   66   0.000066   0.085956245   28351387416   6   80   12   67   0.000067   603   0.000603   0.227519026   4046632313   7   80   18   22   0.000022   66   0.000066   0.102328516   60014623859   8   80   18   67   0.000067   603   0.000603   0.270855065   8565969370  

22.     Formulae used are:  Spark  radius: R(mm)=2.04 x I 0.43 x Ton 0.44   Heat flux Q (W/m 2 ) = (4.57xF c x V x I)/ (π x R 2 )  Crater volume Cv (mm 3 ) = (π x r 2 x h)/3  Material removal rate MRR (mm 3 /min) = (60 x Cv)/(Ton +Toff )  Where,  I=Current (A)  V=Voltage(V)  T on =Pulse on time (s)  T off =Pulse off time (s)   F c =Cathode energy fraction taken as 0.3(50V),0.25(65V),0.15(80V)   r =Radius of crater (mm)   h=Depth of crater (mm) 

23. MODELLING  The modelling steps for all the four sections are similar only the input parameters varies under different conditions.  STEP 1:  Under material properties, the workpiece material Stainless Steel 304 is selected and its properties are fed

24.    Material properties of SS304   

25. STEP 2: Before doing the 2D drawing the analysis type is changed from 3D to 2D  Changing analysis type

26. STEP 3:  The workpiece was designed using ANSYS DESIGN MODELLER with dimensions of 14mm x 10mm [5].  Drawn 2D model  

27. STEP 4:  Create the 2D geometry into a new surface for the ease of geometry drawing  Create surface sketch  

28. STEP 5: Draw a circle in the edge of work piece of diameter 10mm.   Drawn a circle 

29. STEP 6:  Extrude the circle by adding slice material and separate the two sketches. Create the two sketches  

30.    The workpiece was designed using ANSYS DESIGN MODELLER with dimensions of 14mm x 10mm Two-Dimensional workpiece model  

31.     STEP 7:   The workpiece is split into two portions for ease of meshing. The circular cross-section is split with respect to the spark radius using the concept of split edges.   Splitting of edges 

32.     STEP 8:  The workpiece is meshed for FEM analysis using meshing tool in ANSYS. The meshing is done in two parts where the non-circular section is meshed as coarse mesh and circular section is meshed finely with 3 times refinement for better analysis and results Meshed model 

33.    Coarse meshing for non-circular section

34. Fine meshing for circular section   

35. STEP 9: Pulse on time is applied in analysis setting    Pulse-on-time application 

36. STEP 10:    Heat flux Q(W/m 2 ) which represent the energy of spark is applied on the edge of the workpiece   Application of heat flux 

37. STEP 11 :    Heat flux of oxygen(dielectric) is applied on the edge.    Application of heat flux of oxygen (Di-electric) 

38. STEP 12 :    The three non-effected boundaries are insulated by selecting heat flux as 0W.   Insulation of non-affected boundary 

39. STEP 13 :    The solution is found  Simulated solution 

40. RESULTS  OXYGEN DIELECTRIC   Finite Element Analysis based numerical model for oxygen gas di-electric electrical discharge machining of stainless steel 304 and Cu electrode is developed and material removal rate is simulated under different conditions.

41. SIMULATED RESULTS FOR OXYGEN DIELECTRIC  Sl no.   Depth(mm)   Radius(mm)   Crater Volume (mm 3 )   MRR   (mm 3 /min)   MRRe    (mm 3 /min)   Error %   1   0.8   0.81   0.549653051   0.374763444   0.376   0.328871359   2   1.16   1.15   1.606505764   0.417274224   0.414   0.790875431   3   1.65   1.706   5.028872397   0.450346782   0.441   2.119451653   4   0.9   0.875   0.721584563   0.491989475   0.552   10.871472   5   1.2   1.3   2.123716634   0.55161471   0.62   11.02988546   6   1.8   1.75   5.772676502   0.516956105   0.515   0.379826142   7   0.87   0.9   0.737960114   0.503154623   0.794   36.63040007   8   1.35   1.36   2.614810398   0.679171532   0.679   0.025262429   9   1.85   2   7.74926188   0.69396375   0.691   0.428907444   10   0.8   0.86   0.619605847   0.422458532   0.426   0.831330478  

42.      The model is validated by comparing it with available experimental values from the journal. From the table we can see that simulated values of material removal rate in column 5 is comparable to the experimentally found values of MRR. The average error in the simulated values is 3.86%.

43. SIMULATED TEMPERATURE PROFILES FOR OXYGEN   Depth =0.8mm Radius=0.81mm   V=50V    I=12A     T on =0.000066s  

44. 10. V=65V    I=12A       T on =0.000066s       Depth =0.8mm Radius=0.86mm   

45. 19. V=80V    I=12A    T on =0.000066s  Depth =0.75mm Radius=0.75mm 

46. HELIUM DIELECTRIC  Sl no.   Depth(mm)   Radius(mm)   Crater   Volume(mm 3 )   MRR   (mm 3 /min)   MRRe    (mm 3 /min)   Error %   1   0.53   0.48   0.127875387   0.087187764   0.096   9.179412366   2   0.48   0.55   0.152053084   0.013616694   0.016   14.89566169   3   0.35   0.4   0.058643063   0.039983907   0.0385   3.854302612   4   0.5   0.55   0.15838863   0.014184056   0.0128   10.81294051   5   0.38   0.45   0.080581852   0.054942172   0.064   14.15285699   6   0.65   0.75   0.382881605   0.034287905   0.0385   10.94050676   7   0.3   0.25   0.019634954   0.013387469   0.016   16.32832065   8   0.53   0.45   0.112390477   0.010064819   0.0128   21.36860271    SIMULATED RESULTS FOR HELIUM DIELECTRIC   

47.         From the simulated values of MRR we can see that it is close to the experimentally found values for MRR under similar conditions and it further shows the capability of the developed model in the simulation of gas dielectric EDM process.  

48. SIMULATED TEMPERATURE PROFILES FOR HELIUM  V=50V    I=12A   T on =0.000066S    Depth =0.53mm      Radius=0.48mm    

49.         V=80V    I=12A   T on =0.000066s   Depth =0.38mm   Radius=0.45mm    

50. COMPARITIVE ANALYSIS OF OXGEN AND HELIUM  MRR comparison for Helium and Oxygen    

51. SAMPLE CALCULATION  V=50 V  I=12A  T on =0.000066s=66µs  T off =0.000022s=22us  Spark radius R=2.04 x 12 0.43 x 0.000066 0.44 = 0.085956245 mm  Heat flux Q=(4.57 x 0.3 x 50 x 12)/(π x ((0.0859/1000)) 2 ) = 35439234270 W/m 2  Depth = 0.80mm   Radius =0.81mm  Crater volume = (π x 0.81 2 x 0.80)/3= 0.549653051 mm 3   Material removal rate MRR= (60 x 0.549)/ (22+66) = 0.374763444 mm 3 /min

52. CONCLUSIONS  Finite element model for the gas-dielectric electro discharge machining is developed in ANSYS 19.1 Experimental results of gas dielectric electro discharge machining in Oxygen carried was used to validate the simulated results and it was found that developed model was able to obtain results with reasonable accuracy within an error of 3.86%.  It was also found that the material removal rate increases with increase in current and decreases with increase in voltage.

53.        Experimental results of gas dielectric electro discharge machining in Helium was used to validate the simulated results and it was found that developed model was able to obtain results with reasonable accuracy within an error of 12.7%.   When comparing the material removal rate for helium and oxygen it was found the material removal rate in Helium is very low when compared to oxygen. This may be attributed to lower dielectric strength and thermal conductivity of helium when compared to oxygen. 

54. FUTURE WORK  The model can be further extended to simulate the electrical discharge machining under different gases such as Nitrogen.  The impact of different parameters such as pressure, speed of electrode may also be incorporated to the existing model with the help of user defined functions (UDF) in ANSYS.  Effect of different parameters on tool wear rate (TWR) may also be investigated.  The effect of mixture of two or more gases as dielectric on the electro discharge machining process can also be simulated . 

55. REFERENCES Jia Tao, Albert J. Shih, Jun Ni, ”Experimental Study of the Dry and Near-Dry Electrical Discharge Milling Processes”, Journal of Manufacturing Science and Engineering, FEBRUARY 2008, Vol. 130 / 011002-1   Avinash Choudhary, Mohan Kumar Pradhan, ”Finite Element Analysis of Electro Discharge Machining using Ansys”, Proceedings of 1st International Conference on Mechanical Engineering: Emerging Trends for Sustainability Mehrdad Hosseini Kalajahi,Samrand Rash Ahmadi,Samad Nadimi Bavil Oliaei , ”Experimental and finite element analysis of EDM process and investigation of material removal rate by response surface methodology”,International Journal of Advanced Manufacturing Technology (2013) 69:687–704   S Jithin, Ajinkya Raut, Upendra V Bhandarkar, Suhas S Joshi,” FE Modeling for Single Spark in EDM Considering Plasma Flushing Efficiency, Procedia Manufacturing, Volume 26, 2018, Pages 617-628   P. Govindan, Suhas S. Joshi ,”Experimental characterization of material removal in dry electrical discharge drilling “,International Journal of Machine Tools & Manufacture 50 (2010) 431–443

56. THANK YOU