This PPT is all about Powder Mixed Electric Discharge Machining.

1. Study of mrr using Powder mixed edm
Project Part – 1 (ME-781)
BY—
NAME ROLL NO.
BIKASH PATHAK 10800717089
MOHAMMAD SHARIQUE 10800717070
UTTAM THAKUR 10800717027
MD SOHAIL ALAM 10800717072
NIKHIL GUPTA 10800717067
SABNAM DASGUPTA 10800718018
UNDER THE GUIDANCE OF—
Dr. DEBASHISH SARKAR, HOD & ASST. PROFESSOR
DEPARTMENT OF MECHANICAL ENGINEERING
ASANSOL ENGINEERING COLLEGE

2. Contents: 1. Introduction to Non conventional Machining.
2. Electric discharge machining (EDM).
3. Principle of EDM.
4. Principle of Operations.
5. EDM – Electrode material (Tool).
6. Dielectric Fluid.
7. Major Limitation of EDM.
8. Introduction to Powder Mixed Electric Discharge Machining.
(PMEDM).
9. Machining Mechanism of Powder mixed Electric discharge
machining.
10. Factor affecting Machining Parameters PMEDM Process.
11. EDM - Material removal rate.
12. Advantages.
13. Disadvantages.
14. Applications.
15. Conclusion.

3. Non-Conventional Machining:
•Non-Conventional machining process is a special type
of machining process in which there is no direct contact between the tool
and the work piece.
• Non-Conventional methods uses mechanical energy, electrical
energy, thermal energy, or chemical reaction for precise removing metal
to form or finish a part
Note:- EDM is an Example of Non Conventional Machining.

4. EDM ( Electric Discharge Machine)
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.
Sometimes it is referred to as spark machining,
spark eroding, burning, die sinking or wire erosion

5. Principle of EDM

6.  In this process the metal is removed from the work piece due to erosion cause by
rapidly recurring spark discharge between the tool and work piece.
 A thin gap approximately about 0.025mm is maintained between the tool and
work piece by a servo system
 Both tool and work piece are submerged in a dielectric fluid.
 The tool is made cathode and work piece as anode.
 When the voltage across the gap becomes sufficiently high it discharges through
the gap in the form of the spark in interval of from 10 of micro seconds.

7. EDM: Principles of Operations

8. EDM: Principles of Operations
 A DC servo unit or hydraulic cylinder moves the ram (and electrode) in a vertical
motion and maintains proper position of the electrode in relation to the
workpiece.
 During normal operation the electrode never touches the workpiece, but is
separated by a small spark gap.
 The ram moves the electrode toward the workpiece until the space between them
is such that the voltage in the gap can ionize the dielectric fluid and allow an
electrical discharge (spark) to pass from the electrode to the workpiece.
 Each discharge(Spark) melts or vaporizes a small area of the workpiece surface.
 Both the workpiece and electrode are submerged in a dielectric fluid which
acts as an electrical insulator to help control the spark discharges.

9. EDM –Electrode Material (Tool)
 Higher density –for less tool wear and thus less dimensional loss or
inaccuracy of tool .
 High melting point –high melting point leads to less tool wear due to
less tool material melting for the same heat load .
 The followings are the different electrode materials which are used
commonly in the industry:
• Graphite
• Electrolytic oxygen free copper
• Brass

10. Dielectric Fluid
 It’s a dielectric material in liquid state.
 They are used as electrical insulators in high voltage applications.
 Dielectric fluid should provide an air free machining environment to the
workpiece.
 It breaks down and ionized when collided with electrons.
 It helps in convey the spark.
 It helps in cooling the electrode, Workpiece and the system.
 It carried away the eroded particles with it.
 It may be deionized water, kerosene, transformer oil and EDM oil.

11. Major Limitation of EDM.
Low Material Removal Rate
of conventional EDM.
Low Surface Finish in
Conventional EDM.
Higher machining time.
Higher Tool Wear Rate.
Poor Overcut size, causes
easy removal of wear debris
particles and better
machining efficiency

12. Introduction to Powder Mixed Electric Discharge Machining.
(PMEDM)
 The use of semi conductive solid particles in EDM Dielectric
named as PMEDM.
 It is a recent innovation of EDM for enhancing its capabilities.
 To enhance the machined surface properties by means of fine powders of Silicon,
Graphite, Aluminum are mixed with dielectric solution.
 Reduces Surface Roughness(SR), Tool Wear Rate(TWR).
 Increases overcut size and Material Removal Rate (MRR).
 Any material that is electrically conductive can be machined regardless of its
hardness, toughness, strength and microstructure.
Powders used in machining are - 1. Aluminum Oxide.
2. Graphite.
3. Silicon Carbide.
4. Copper Powder.

13.  Tool is connected to cathode.
 A rectangular Box will be placed upon
anode end and should be made of a
electrically conductive material.
 Box is placed, 1 ltr (approx) dielectric
fluid is poured with some percentage of
powder into the box.
 A motor is installed to continuously
circulate powder particles with
dielectric fluid.

14.  Material Removal Rate (MRR) is greatly influenced by current, pulse-on
time and electrode materials. Type of powder and its concentration have
lower contribution to the MRR improvement.
 Tool Wear Rate(TWR) is basically influenced by powder concentration,
whereas pulse-on time, current, electrode material and type of powder
have less contribution.
 Overcut size improvement is influenced by pulse-on time and powder
concentration.
 Powder concentration and supplied current has significant effect to
improve Surface Roughness
Factor affecting Machining Parameters PMEDM Process.

15. EDM – Material Removal Rate
In EDM, the metal is removed from both workpiece and tool
electrode.
 MRR depends not only on the workpiece material but on the material
of the tool electrode and the machining variables such as pulse
conditions, electrode polarity, and the machining medium.
 In this regard a material of low melting point has a high metal
removal rate and hence a rougher surface.
MRR(g/min) = Workpiece weight loss (g)
Machining time (Min)
 Typically Material Removal Rate Range from – (0.1 to 400) g/min

16. Advantages
 Any electrically conductive materials can be machined.
 Stress free complicated geometries can be produced.
 Eliminates the necessity of grinding and fine surface finish.
 There is no direct contact between tool and workpiece. Therefore
delicate sections and weak materials can be machined without any
distortion.

17. Disadvantages
 The slow rate of material removal.
 For economic production, the surface finish specified should not be too fine.
 Workpiece material should be electrically conductive.
 Power consumption is high.
 Excessive tool wear occurs during machining.

18. Applications
 Delicate work piece like copper parts can be produced by EDM.
 In high precision instruments where large area with fine surface finish are
required to be machined.
 Can be applied to all electrically conducting metals and alloys irrespective of their
melting points, hardness, toughness, or brittleness.
 It can be used where rough machining is required.
 Other applications: deep, small-dia holes using tungsten wire as tool, narrow slots,
cooling holes in super alloy turbine blades, and various intricate shapes.

19. Conclusion
Powder mixed dielectric is a good research promising area .
Most of the research work has been with Al, Si, and graphite
powders and some with other types of powder like Cr, Ni, Mo,
etc. , but only a few has touched the introduction of using
powders into EDM. Most of the available research works on
powder-mixed dielectric have studied the impact of such
machining on MRR, surface roughness and TWR etc. Much
investigation and more trails are needed to check the
applicability and measure the performance of EDM with
Powder particles in dielectric.

20. Thank you.