This slide is about how to design and develop a rotating work-piece holding mechanism for die sinking EDM process.

1. DESIGN AND DEVELOPMENT OF ROTATING
WORKPIECE HOLDING MECHANISM IN DIE
SINKING EDM
SAHIL DEV (10406EN016)
IDD PART V SEMESTER X
PRODUCTION ENGG.
SUPERVISED BY: DR. U.S. RAO

2. CONTENTS
 Introduction
 Design and Developments
 Fabrication of Parts
 Experimental Analysis
 Result and Discussion
 References
2

3. INTRODUCTION
 Electric Discharge Machining, also known as Spark Machining, Spark
Erosion.
 Used on hard metals.
 Works with electrically conductive materials.
3

4. HISTORY 4
 Erosive effect was discovered by Joseph Priestly, in 1770.
 In 1943, two Russian scientist found erosive effect can be controlled more
precisely when electrodes were dipped in dielectric fluid.
 Later an American Team developed an EDM machine for removing broken
drills and taps from aluminium casting.
 Today, it is a viable technique which is used in metal working industry.

5. PROCESS: SPARK INITIATION 5
Spark occurs within a column of ionized dielectric fluid

6. MATERIAL REMOVAL MECHANISM 6
Spark on, workpiece and tool material vaporized

7. DIELECTRIC
 Insulation
 Ionization
 Cooling
 Removal of waste particles
 Example – Deionized water, kerosene, etc.
7

8. PROCESS PARAMETERS
 Peak Voltage
 Peak Current
 Pulse Duration
 Polarity
8

9. PERFORMANCE MEASUREMENT
 Material Removal Rate
 Tool Wear Rate
 Surface Quality
9

10. DESIGN AND DEVELEOPMENTS 10
3d model of the whole setup made in Solidswork package.

11. BILL OF MATERIALS
S. No. Component Material Mechanical Property
1 Spur Gear x 2 AL-5052
UTS = 228 MPa
YS = 193 MPa
2 Gear Base Rod x 6 A-36 Mild Steel
UTS = 399.8 MPa
YS = 250.2 MPa
3 Gear Mounting Plate x 2 A-36 Mild Steel
UTS = 399.8 MPa
YS = 250.2 MPa
4 Workpiece Holder x 1 A-36 Mild Steel
UTS = 399.8 MPa
YS = 250.2 MPa
6 Motor Mounting Plate x 1 A-36 Mild Steel
UTS = 399.8 MPa
YS = 250.2 MPa
7 Motor Base Rod x 4 A-36 Mild Steel
UTS = 399.8 MPa
YS = 250.2 MPa
8 Base x 1 A-36 Mild Steel
UTS = 399.8 MPa
YS = 250.2 MPa
9 Collar Bearing x 2 A-36 Mild Steel
UTS = 399.8 MPa
YS = 250.2 MPa
11
NOTE: The quantities listed above are per one setup.

12. SELECTION OF SPUR GEAR
Properties
No. of Teeth (z) 80
Pitch Diameter (Dp) 160mm
Min Bore (d) 20mm
Max Bore 98mm
Outside Diameter (D) 174mm
Module (m) 2.0
Diametrical Pitch (P) 0.5
Thickness (k) 20mm
12

13. DESIGN OF BASE RODS
According to Euler’s theory: 𝐹 =
𝜋2 𝐸𝐼
𝑙 𝑒
2
As base rod are fix at one end and free at other end, 𝑙 𝑒 = 2𝑙
Area moment of inertia for circular cross section, 𝐼 =
𝜋𝑑4
64
13

14. GEAR BASE ROD
Calculation for Gear Base Rod
Length of the rod (l1) = 180mm
Diameter of the rod (d1) = 20mm
Modulus of elasticity (E) = 215GPa
𝐹 =
3.142 × 215 × 106 × 3.14 × (20 × 10−3)4
4 × 64 × (180 × 10−3)2
𝑁
𝐹 = 1.28 × 105 𝑁
14

15. MOTOR BASE ROD
Length of the rod (l2) = 235mm
Diameter of the rod (d2) = 16mm
Modulus of elasticity (E) = 215GPa
Area moment of inertia for circular cross section, I =
πd4
64
𝐹 =
3.142 × 215 × 106 × 3.14 × (16 × 10−3)4
4 × 64 × (235 × 10−3)2
𝑁
𝐹 = 3.08 × 104 𝑁
15

16. SELECTION OF DC MOTOR
Shear Force Calculation
Newton’s law of viscous friction,
𝑡 = µ
𝑑𝑢
𝑑𝑦
𝐹 = ∫
µ. 𝑟. 𝑤. 2𝜋𝑟. 𝑑𝑟
𝑘
𝐹 =
2𝜋. µ. 𝑤.
𝑘
𝐷 𝑝
3
3
𝐷𝑦𝑎𝑛𝑎𝑚𝑖𝑐 𝑉𝑖𝑠𝑐𝑜𝑠𝑖𝑡𝑦 = 𝐾𝑖𝑛𝑒𝑚𝑎𝑡𝑖𝑐 𝑉𝑖𝑠𝑐𝑜𝑠𝑖𝑡𝑦 × 𝐷𝑒𝑛𝑠𝑖𝑡𝑦
Kinematic viscosity of dielectric = 2.0×10-6 m2/s
Density of dielectric = 0.790kg/m3
16

17. CONTINUED…
Dynamic viscosity (µ) = 1.6×10-6 N-s/m2
Thickness of spur gear (k) = 20mm
Pitch diameter (DP) = 160mm
Angular velocity (w) = 10.5rad/s
𝐹 =
2 × 3.14 × 1.6 × 10−6
× 10.5
20 × 10−3
(160 × 10−3
)3
3
𝑁
F = 7.18×10-6 N
17

18. CONTINUED…
Torque Calculation
Since, 𝐼𝑛𝑡𝑒𝑟𝑖𝑎 =
1
2
𝑀𝑟2
Mass of spur gear = 1.1 kg
Pitch diameter (DP) = 160mm
𝐼𝑔𝑒𝑎𝑟 =
1
2
× 1.1 ×
160 × 10−3
4
2
𝑘𝑔. 𝑚2
𝐼𝑔𝑒𝑎𝑟 = 3.45 × 10−3
𝑘𝑔. 𝑚2
18

19. CONTINUED…
𝑇𝑜𝑟𝑞𝑢𝑒 𝑟𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝑇 = 𝐼𝑔𝑒𝑎𝑟 × α 𝑚𝑎𝑥
αmax = 10.5 rad/s2
𝑇 = 3.45 x 10-3 x 10.5 N.m
𝑇 = 0.036 N.m
𝑃𝑜𝑤𝑒𝑟 𝑟𝑒𝑞𝑢𝑖𝑟𝑒𝑑 𝑃 = 𝑇. 𝑤
𝑃 = 0.036 × 10.5
𝑃 = 0.3768 𝑊
19

20. DESIGN OF WORKPIECE HOLDER 20
► No mechanical force will be acting on
the workpiece holder as there is no
direct contact between tool electrode
and workpiece.

21. GEAR MOUNTING PLATE DESIGN
 Provide support to spur gear.
 To keep the spur gear
horizontally stable.
21

22. DESIGN OF MOTOR MOUNTING PLATE 22

23. FABRICATION OF PARTS 23
Material used: Aluminium 5052
Machining process employed: Milling, grinding, hobbing,
broaching, casting and forging.
Modifications in the original design: The dimension of
the fabricated spur gear is taken from the standard gear
size which is different from the model design and to
reduce the material cost we modified the design with
grooves on it.

24. BASE ROD 24
Material used: A-36 Mild Steel
Machining process employed: Facing, turning,
cutting, centering, drilling and thread cutting.
Modifications in the original design: None

25. WORKPIECE HOLDER 25
Material used: A-36 Mild Steel
Machining process employed: Facing,
turning, cutting, centering, cut-off, boring,
drilling, reaming and grinding.
Modifications in the original design: None

26. GEAR MOUNTING PLATE 26
Material used: A-36 Mild Steel
Machining process employed: Facing, turning,
cutting, centering, boring, drilling and grinding.
Modifications in the original design: None

27. MOTOR MOUNTING PLATE 27
Material used: A-36 Mild Steel
Machining process employed: Shaping, centering, drilling and grinding.
Modifications in the original design: To reduce the material wastage we modified the mounting
as rectangular plate instead of using square plate as we made in the 3d model.

28. EXPERIMENTAL ANALYSIS 28

29. MACHINE AND INSTRUMENS
 Smart ZNC Electric Discharge Machine
 Weighing Machine: To find out the tool wear and the material removed
from the work piece in gram. Least count = 0.0001g
 Stereo Zoom Microscope: To take the photographs of the tool and the
machined hole to study the taper and wear profile of the tool.
 Clamp
29

30. EXPERIMENT-1
 To find out the effect of current on MRR and TWR in EDM process
30

31. MRR vs CURRENT 31
3.2
3.7
4.75
5.23
4 5 6 7
MRRx10-5(cm3/s)
Current (A)
MRR VS CURRENT

32. TWR vs CURRENT 32
3.47
6.82
14.3
25.9
4 5 6 7
TWRx10-7(cm3/s)
Current (A)
TWR VS CURRENT

33. EXPERIMENT-2
 To find out the effect of Ton Time on MRR and TWR in EDM process.
33

34. MRR vs Ton Time 34
1.98
7.8
8.44
7.55
10 50 100 200
MRRx10-5(cm3/s)
Ton Time (µs)
MRR VS TON TIME

35. TWR vs Ton Time 35
7.55
3.7
0.78 0.63
0
1
2
3
4
5
6
7
8
10 50 100 200
TWRx10-6(cm3/s)
Ton Time (µs)
TWR VS TON TIME

36. EXPERIMENT-3
 To find out the change in the cylindricity of the circular tool with high
depth to tool diameter ratio.
36

37. 37

38. 38

39. 39

40. TAPER VS DEPTH OF HOLE 40
4.13
5.69
7.65
9.25
0
2
4
6
8
10
5 12 18 25
Taper(µm/mm)
Depth of cut (mm)
TAPER VS DEPTH OF CUT

41. SUMMARY
 With increase in current, increase in Material Removal Rate and Tool Wear
Rate is obtained.
 With increase in Ton Time, increase in Material Removal Rate and decrease
in Tool Wear Rate is obtained.
 With increase in depth of cut to tool diameter ratio side tool wear occurs
so that we get a taper shape of tool profile.
 Successfully completion design, development, modification and fabrication
of the rotating workpiece holding mechanism.
41

42. SCOPE FOR FUTURE WORK
 Verification of the fabricated rotating workpiece holding mechanism.
 Performance measurement of the process from the rotating aspect.
 Study of taper problem in high aspect ratio machining from the rotating
aspect.
42

43. REFERENCES
 Electrical Discharge Machining by Society of manufacturing Engineers-
www.sme.org.
 Electrical Discharge Machining By Steve Krar.
 Ali Ozgedik and Can Cogun (2006). An experimental investigation of tool
wear in electric discharge machining, The International Journal of Advance
Manufacturing Technology, Vol. 27, 488–500.
 Y. H. Guu and H. Hocheng (2001), Effects of workpiece rotation on
machinability during Electrical Discharge Machining, Material and
Manufacturing Process, Vol. 16, No. 1, 91-10.
 Chinmaya P. Mohanty, Jambeswar Sahu and S.S.Mahapatra (2013).
Thermal-structural Analysis of Electrical Discharge Machining Process,
Procedia Engineering, Vol. 51, 508– 513.
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44. THANK YOU
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