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