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EFFECTS OF PROCESS PARAMETER ON MACHINING OF HC-HCR DIE
STEEL BY EDM USING COPPER ELECTRODE
SUBMITTED BY :- GUIDED BY :-•Shyam Sundar (11104879) Mr. Jaspreet Singh•Sohil Kumar (11104870) •Sumit kumar (11110667)•Saveen (11104893)
CONTENTS
Material removal processElectrical discharge machiningEquipments and experimental setupProcess parametersAdvantages and disadvantages of EDMApplications of EDM
CONT……
Properties of hc-hcr Properties of copper Observations Result Conclusions
MATERIAL REMOVAL PROCESS
Shaping operations ot get finished surface by removing material.
Basically two types :-
• Conventional
• Non conventional
CONVENTIONAL MACHINING PROCESS
Tool and work piece are in contact .
Discontinuous or continuous chips are formed.
Examples,Turning,drilling,miling etc
NON CONVENTIONAL MACHINING
Used for very hard,tough,fragile materials.
Tool and work piece not in contact.
No chips formation,small size debris formed.
EDM,EBM,LBM,AJM,USM,WJM etc.are used
ELECTRICAL DISCHARGE MACHINING Non conventional type machining.
Machined only electric conductors.
Use spark discharges to erode material.
Cavity formed is of tool shaped used as erosion occurs in confined area.
Dielectric fluid surrounds both tool and work piece.
Servo mechanism gives gap .005-.001 inch between tool and work piece.
PRINCIPLE OF EDM
Large number of electrons flow from tool to job and ions from job to tool.
Such movement visually seen as spark. kinetic energy of electrons and ions is
converted into heat flux. This heat flux leads to excess temperature
and melts the metal. Material removal occurs due to melting.
EQUIPMENTS AND EXPERIMENTAL SET UP
Dielectricreservoir, pump,circulation system. Power generator and control unit. Working tool with work holding device. X-Y table accomodating working table. Tool holder,servo mechanism.
SET UP OF EDM
PROCESS PARAMETERS
Peak current
Pulse on time
Pulse off time
PEAK CURRENT : - in each pulse on time,current increases untill it reaches a present level,expressed as peak current.
PULSE ON TIME :- time period during which machining takes place.
PULSE OFF TIME :- time period during which re-ionization of dielectric takes place.
ADVANTAGES OF EDM
Machining of complex shapes. Machining hard materials. Very high accuracy. High degree of automation. Absence of forces.
DISADVANTAGES OF EDM
very slow process. Predictability of the gap. Needs electrical conductivity.
APPLICATIONS OF EDM
In aerospace,automative and nuclear industries to machined very hard metals and alloys.
To machined tough,intricate shape,fragile machining.
PROPERTIES AND COMPOSITION OF HC-HCR DI STEEL
High dimensional stability. Wear resistance. C=1.7 -2% Cr=12.0% Si=0.3% Mn=0.3%
PROPERTIES OF COPPER
Good electrical conductivity.
Good thermal conductivity.
Corrosion resitant.
Ductile.
OBSERVATIONS
RESULT
EFFECT ON M.R.R.
PEAK CURRENT MRR Increases with increase in current for any value of
pulse on time. Higher curent makes spark more strong which increases
MRR. PULSE ON TIME With longer pulse on duration more material will melt away. PULSE OFF TIME Increase in pulse off time results in reduced pulse frequency
due to which reduction in MRR occurs.
EFFECT ON T.W.R.
PEAK CURRENT Higher current increases pulse energy, which
increases heat energy rate which increases melting tool and increases TWR.
PULSE ON TIME TWR increases with increasing pulse on time
because more melting of electrode occurs at higher pulses due to increase in pulse energy.
PULSE OFF TIME TWR decreases with increase in pulse off time
because pulse frequency reduces.
EFFECT ON S.R.
PEAK CURRENTSR Increases with increase in current for any value of pulse on time.Higher curent makes spark more strong which increases depth of cut,which increases SR.
PULSE ON TIMEWith longer pulse on duration more material will melt away, hence more SR.
PULSE OFF TIME Increase in pulse off time results in reduced pulse frequency due to which reduction in SR occurs.
CONCLUSIONS
For MRR the most significant factor was found to be peak current followed by pulse on time and the least significant was pulse off time. The MRR increased nonlinearly with the increase in current.
For SR the most significant factor was again current followed by pulse on time and lastly the pulse off time. SR increased significantly with the increase in current in a nonlinear fashion. For increase in pulse on time SR increased.
For less TWR most significant factor is less current and low pulse on time.
THANK YOU