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Optimization of wedm process parameters using taguchi method


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Optimization of wedm process parameters using taguchi method

  1. 1. OPTIMIZATION OF WIRE ELECTRICAL DISCHARGE MACHINING PROCESS PARAMETERS USING TAGUCHI METHOD Overview • • • • Wire Electric Discharge Machining Process Parameters Taguchi Design of Experiments Grey Based Taguchi Method of Optimization Raju Kumar (Roll no 1002061) Dharam Deo Prasad (Roll no 1002062) 1
  2. 2. ELECTRIC DISCHARGE MACHINING Introduction  Sometimes it is referred to as spark machining, spark eroding, burning, die sinking or wire erosion  Its a manufacturing process whereby a desired shape is obtained using electrical discharges (sparks).  Material is removed from the workpiece by a series of rapidly recurring current discharges between two electrodes, separated by a dielectric liquid and subject to an electric voltage.  One of the electrodes – ‘tool-electrode’ or ‘tool’ or ‘electrode’.  Other electrode - workpiece-electrode or ‘workpiece’.  As distance between the two electrodes is reduced, the current intensity becomes greater than the strength of the dielectric (at least in some points) causing it to break. 2
  4. 4. WIRE ELECTRIC DISCHARGE MACHINING Introduction  Also known as wire-cut EDM and wire cutting.  A thin single-strand metal wire (usually brass) is fed through the workpiece submerged in a tank of dielectric fluid (typically deionized water).  Used to cut plates as thick as 300 mm and to make punches, tools, and dies from hard metals that are difficult to machine with other methods.  Uses water as its dielectric fluid; its resistivity and other electrical properties are controlled with filters and de-ionizer units.  The water flushes the cut debris away from the cutting zone.  Flushing is an important factor in determining the maximum feed rate for a given material thickness.  Commonly used when low residual stresses are desired, because it does not require high cutting forces for material removal. 4
  6. 6. WIRE ELECTRIC DISCHARGE MACHINING WEDM Components -four major components • • • • Computerized Numerical Control (CNC) - The Brains. Power Supply -The Muscle Mechanical Section - The Body Dielectric System -The Nourishment 6
  7. 7. WIRE ELECTRIC DISCHARGE MACHINING ADVANTAGES • Better stability and higher productivity . • Higher machining rate with desired accuracy and minimum surface damage. • Uses in the production of forming tools. • To produce plastics moldings, die castings, forging dies etc. • Can be applied to all electrically conducting metals and alloys irrespective of their melting points, hardness, toughness, or brittleness. 7
  8. 8. WIRE ELECTRIC DISCHARGE MACHINING Applications – Wire EDM •Special form of EDM - uses a continuously moving conductive wire electrode. Material removal occurs as a result of spark erosion as the wire electrode is fed, from a fresh wire spool, through the workpiece. Horizontal movement of the worktable (CNC) determines the path of the cut. Application - Machining of super hard materials like polycrystalline diamond (PCD) and cubic boron nitride (CBN) blanks, and other composites. Carbon fiber composites are widely used in aerospace, nuclear, automobile, and chemical industries, but their conventional machining is difficult 8
  9. 9. MACHINING PROCESS PARAMETRS • Main Machining Parameters Pulse-on time(μs) Pulse-off time(μs) Wire feed(mm/min) Gap voltage(volt) 9
  10. 10. The Taguchi Approach to DOE Orthogonal array From every trial series we can obtain an average result level and a measure of the variation, si, i=1,2, … ,9. These values can then be used as a basis for choosing the combination of factor levels that provides the most robust design. Control Factors EXP.NO A B C D 1 1 1 1 1 2 1 2 1 2 3 1 3 3 3 4 2 1 2 3 5 2 2 3 1 6 2 3 1 2 7 3 1 3 2 8 3 2 1 3 9 3 3 2 1 10
  11. 11. The Taguchi Approach to DOE Process parameters & their levels symbol Control factor Unit Level 1 Level 2 Level 3 A Pulseon time μs 4 6 8 B Pulseμs off time 4 6 8 C Wire feed mm/min 2 4 6 D Gap voltage volts 40 50 60 11
  12. 12. Optimizing Techniques using Taguchi method Two types of optimizing techniques 1. Grey based Taguchi method 2. Fuzzy based Taguchi method We have used grey based Taguchi method for optimizing machining parameters in wire EDM using LM6B4C composite material produced by stir casting . Two types of LM6B4C Composite material was manufactured as workpiece for cutting by WEDM. •LM6 +5%B4C •LM6 +10%B4C 12
  13. 13. Grey based Taguchi method Introduction • • • widely used in different fields of engineering to optimize the process parameters. To solve the multiple performance characteristics problems , the Taguchi method is coupled with grey relational analysis. An OA provides a set of well-balanced experiments, and Taguchi’s signal-to-noise. (S/N) ratios, which are logarithmic functions of the desired output, serve as objective functions for optimization. 13
  14. 14. Grey based Taguchi method Procedure of the grey-based Taguchi method. 14
  15. 15. Grey based Taguchi method To find S/N ratios values For MRR And, For surface roughness and kerf width(k) Where n = number of replications and yij = observed response value Where i=1, 2... ....n; j = 1, 2...k. 15
  16. 16. Grey based Taguchi method Further analysis & calculations • • • • find normalized S/N ratio values . find grey relational coefficient . find grey relational grade. Draw graphs for Grey relational grades for maximum MRR, Minimum Ra and minimum kerf width . • find optimum levels of the factors from the graphs & the tables of experiments separately. • Compare both the optimal values obtained from the tables & graphs. 16
  17. 17. Grey based Taguchi method RESULTS AND DISCUSSION • Confirmation test for the optimal parameter setting was conducted. • LM6 +10%B4C has the optimal value within the orthogonal array . • LM6 +5%B4C the optimal value from the L9 orthogonal array is different from the optimal value obtained from the Grey theory design . • Hence a conformation experiment is conducted to find the improvements in the process. 17
  18. 18. Grey based Taguchi method RESULTS AND DISCUSSION Conformation experiment for LM6 +5%B4C Optimal process parameters Orthogonal Array Level MRR (g/min) Time(sec) Ra (μm) Kerf(mm) A2B2C3D1 Grey theory Design A2B1C3D1 0.0612 0.0841 2.13 1.55 3.26 3.79 0.336 0410 18
  19. 19. Grey based Taguchi method RESULTS AND DISCUSSION The optimal process parameters based on Grey Relational Analysis For Aluminium boron carbide (5%) for Aluminium boron carbide (10%) 40 V Gap Voltage 40 V Gap Voltage 4 μs pulse on-time 4 μs pulse on-time 6 μs pulse off-time 4 μs pulse off-time 6 mm/minute Wire Feed rate 2 mm/minute Wire Feed rate 19
  20. 20. Grey based Taguchi method CONCLUSION • The Material Removal Rate shows an increased value of 0.0612g/min to 0.0841g/min. • The time shows a reduced value of 2.13 sec to 1.55 sec . • Positive indicators of efficiency in the machining process. 20
  21. 21. Grey based Taguchi method THE END THANK YOU 21