DESIGN AND DEVELOPMENT OF ROTATING WORKPIECE HOLDING MECHANISM IN DIE SINKING EDM

SAHIL DEV (10406EN016)IDD PART V SEMESTER XPRODUCTION ENGG.

SUPERVISED BY: DR. U.S. RAO

2CONTENTS

Introduction Design and Developments Fabrication of Parts Experimental Analysis Result and Discussion References

3INTRODUCTION

Electric Discharge Machining, also known as Spark Machining, Spark Erosion.

Used on hard metals. Works with electrically conductive materials.

4HISTORY

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.

5PROCESS: SPARK INITIATION

Spark occurs within a column of ionized dielectric fluid

6MATERIAL REMOVAL MECHANISM

Spark on, workpiece and tool material vaporized

7DIELECTRIC

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

PROCESS PARAMETERS

Peak Voltage Peak Current Pulse Duration Polarity

8

9PERFORMANCE MEASUREMENT

Material Removal Rate Tool Wear Rate Surface Quality

10DESIGN AND DEVELEOPMENTS

3d model of the whole setup made in Solidswork package.

11BILL OF MATERIALS S. No. Component Material Mechanical Property

1 Spur Gear x 2 AL-5052 UTS = 228 MPaYS = 193 MPa

2 Gear Base Rod x 6 A-36 Mild Steel UTS = 399.8 MPaYS = 250.2 MPa

3 Gear Mounting Plate x 2 A-36 Mild Steel UTS = 399.8 MPaYS = 250.2 MPa

4 Workpiece Holder x 1 A-36 Mild Steel UTS = 399.8 MPaYS = 250.2 MPa

6 Motor Mounting Plate x 1 A-36 Mild Steel UTS = 399.8 MPaYS = 250.2 MPa

7 Motor Base Rod x 4 A-36 Mild Steel UTS = 399.8 MPaYS = 250.2 MPa

8 Base x 1 A-36 Mild Steel UTS = 399.8 MPaYS = 250.2 MPa

9 Collar Bearing x 2 A-36 Mild Steel UTS = 399.8 MPaYS = 250.2 MPa

NOTE: The quantities listed above are per one setup.

12SELECTION OF SPUR GEAR

PropertiesNo. 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

13DESIGN OF BASE RODSAccording to Euler’s theory: As base rod are fix at one end and free at other end, Area moment of inertia for circular cross section,

14GEAR BASE RODCalculation for Gear Base RodLength of the rod (l1) = 180mmDiameter of the rod (d1) = 20mmModulus of elasticity (E) = 215GPa

15MOTOR BASE RODLength of the rod (l2) = 235mmDiameter of the rod (d2) = 16mmModulus of elasticity (E) = 215GPaArea moment of inertia for circular cross section, I =

16SELECTION OF DC MOTORShear Force CalculationNewton’s law of viscous friction,

Kinematic viscosity of dielectric = 2.010-6 m2/sDensity of dielectric = 0.790kg/m3

17CONTINUED…

Dynamic viscosity () = 1.610-6 N-s/m2

Thickness of spur gear (k) = 20mmPitch diameter (DP) = 160mmAngular velocity (w) = 10.5rad/s

F = 7.1810-6 N

18CONTINUED…Torque CalculationSince, Mass of spur gear = 1.1 kgPitch diameter (DP) = 160mm

19CONTINUED…

= 10.5 rad/s2

= 3.45 x 10-3 x 10.5 N.m = 0.036 N.m

20DESIGN OF WORKPIECE HOLDER► No mechanical force will be acting

on the workpiece holder as there is no direct contact between tool electrode and workpiece.

21GEAR MOUNTING PLATE DESIGN

Provide support to spur gear. To keep the spur gear

horizontally stable.

22DESIGN OF MOTOR MOUNTING PLATE

23FABRICATION OF PARTS

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.

24BASE ROD

Material used: A-36 Mild Steel

Machining process employed: Facing, turning,

cutting, centering, drilling and thread cutting.

Modifications in the original design: None

25WORKPIECE HOLDER

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

26GEAR MOUNTING PLATE

Material used: A-36 Mild Steel

Machining process employed: Facing, turning,

cutting, centering, boring, drilling and grinding.

Modifications in the original design: None

27MOTOR MOUNTING PLATE

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.

28EXPERIMENTAL ANALYSIS

29MACHINE 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

30EXPERIMENT-1

To find out the effect of current on MRR and TWR in EDM process

31MRR vs CURRENT

4 5 6 7

3.23.7

4.755.23

MRR vs Current

Current (A)

MRR

x 1

0-5

(cm

3/s)

32TWR vs CURRENT

4 5 6 7

3.47

6.82

14.3

25.9

TWR vs Current

Current (A)

TWR

x 10

-7 (

cm3/

s)

33EXPERIMENT-2

To find out the effect of Ton Time on MRR and TWR in EDM process.

34MRR vs Ton Time

10 50 100 200

1.98

7.88.44

7.55

MRR vs Ton Time

Ton Time (µs)

MRR

x 1

0-5

(cm

3/s)

35TWR vs Ton Time

10 50 100 2000

1

2

3

4

5

6

7

8 7.55

3.7

0.78 0.63

TWR vs Ton Time

Ton Time (µs)

TWR

x 10

-6 (

cm3/

s)

36EXPERIMENT-3

To find out the change in the cylindricity of the circular tool with high depth to tool diameter ratio.

37

38

39

40TAPER VS DEPTH OF HOLE

5 12 18 250123456789

10

4.13

5.69

7.65

9.25

Taper vs Depth of Cut

Depth of cut (mm)

Tape

r (µ

m/m

m)

41SUMMARY

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.

42SCOPE 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.

43REFERENCES 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.

44

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