Presented by;MURLI SHESHERAO KUMBHARKAR

141413003T.Y Production ( S/W)

Mr. S.U. GHUNAGEGuide,

Assistant ProfessorProduction Engineering & Industrial

Management DepartmentCollege of Engineering Pune.

STUDY OF DISCHARGE MECHANISM IN ELECTROCHEMICAL DISCHARGE

MACHINING PROCESS

Contents:-

IntroductionNeed of ECDMWorking Principle of ECDMMaterial Removal Mechanism in ECDMExperimental setup of ECDMMain Subsystem of ECDMMain Influencing parametersAdvantages over ECM/EDMDisadvantages over EDM/ECMApplication of ECDMComparison between ECDM, EDM and ECMReferences

Introduction:-

• Electrochemical discharge machining is the combination of Electric discharge machining (EDM) and Electrochemical machining (ECM) process.

• Electrochemical Discharge Machining (ECDM) process is mostly applied for micro-machining and scribing hard and brittle, non-conducting materials like glass, quartz, ceramics etc.

• The work first on the Electrode effect, anode or cathode effects reported by Fizeau and his group of researchers and Foucault and his co-researchers in 1844.

Introduction:-

• It was introduced in 1968 as electro discharge drilling by Karafuji and Suda.• It knows different name such as : ESCM – Electro Chemical Spark Machining ( by V.K. Jain

et al.) SACE – Spark Assisted Chemical Engraving ( by Fascio et

al.) ECAM – Electro Chemical Anode Machining ( by Kubota) DMNC – Discharge Machining of Non-Conductors ( by

Cook et al. ) SAE – Spark Assisted Etching ( by Daridon et al. )

Need of ECDM :

1. High Accuracy and Surface Finish2. High Strength Alloys3. Complex Surfaces4. Technology Advancement5. Machining on non-conducting materials

.

• The working principle in ECDM is by combination of thermal and chemical mechanisms.

• When a high potential difference is applied between the two electrodes ( tool and work piece ) which are kept a few microns apart gas bubbles start forming continuously at both the electrodes.

Working Principle of ECDM :-

Material Removal Mechanism in ECDM :-

MRR Mechanism

Thermal mode

Melting Vaporization

Chemical mode

Etching

Experimental setup of ECDM :-

• Machine Setup : Usually it is a table top fabricated machine or a specialized set-up comprising of all the necessary features.• Power supply : consisting

of AC to DC converter and Voltage modulator or pulsed modulator.• Control system : Consists

of micro-controller or servo operated subsystem to provide flexibility to tool or work piece.

Main Subsystem of ECDM :-

Main Influencing parameters :-

Electrolyte Concentration Voltage Gas Film Spark Generation Tool Electrode Auxiliary Electrode

Advantages over ECM/EDM :-

• The surface obtained have better finish than EDM and ECM.

• Suitable for non-conducting materials.• High accuracy.• Methods does not leave any chips or burrs.• Less power consumption.

• Set-up is not costly and can be developed or fabricated

on exiting facility through modification and attachments.

Disadvantages over EDM/ECM:-

• Chances to electrode wear.• Initial cost of is high.• Thickness of ceramic material can be

machined is limited to 1.5 mm.• Radial overcut.

Application of ECDM :-ECDM is novel hybrid micro-machining technology for production of :• Through and blind micro-holes • Micro-grooves • Micro-slots• Micro-channels and Complex shapes

produced in non-conducting materials ( quartz, glass, and ceramics) etc.

• Miniature features of turbine blades ( micro-turbulated cooling holes )

• Filters for food and textiles industries• Micro-electro seam welding for copper plate• Industrial applications like bearings, computer

parts, artificial joints, cutting tools, electrical and thermal insulators etc.

• Trueing and Dressing of grinding wheels.

Application of ECDM :-

Comparison between ECDM, EDM and ECM

ASPECTS ECM EDM ECDM

PRINCIPLE Anodic dissolution Spark erosion Both

POWER 10,000A,2-3V,DC 200A,50-200V,DC 3-4A,40V,DC

WORK PIECE

Conductive Conductive Conductive & non- conductive

MRR Less Less 5times faster than EDM

TOOL WEAR

Less than both Higher than ECDM Less than EDM

ACCURACY

Higher than EDM Dimensional accurate :+-.03mm

+-.01mm

SURFACE FINISH

Higher than both Less Higher than EDM

COST Less initial than ECDM

Less initial than ECDM

High

1) S.K Hajra Choudhury, A.K Hajra Choudhury “Workshop technology” Volume:2 machine tools, Media promoters and publishers pvt. ltd. Thirteenth edition (2010) pp.605-650. 2) Amitabha Ghosh “Electrochemical Discharge Machining: Principle and Possibilities” Sadhana Vol.22, Part 3, 1997,pp. 435-447. @ Printed India. 3) B. Doloi, B. Bhattacharyya and S.K. Sorkhel “ Electrochemical Discharge Machining of Non-Conducting Ceramics ” DEF SCI J, Vol49, No 4, August 1999, pp.331-338@1999, DESIDOC.

4) Indrajit Basak, Amitabha Ghosh “Mechanism of material removal in electrochemical discharge machining: a theoretical model and experimental verification” Journal of Materials Processing Technology 71 (1997) 350-359.5) Anjali V. Kulkarni “Electrochemical Discharge Machining Process” DEF SCI J, VOL. 57, NO.5, September2007.6) Anjali. Kulkarni, R. Sharan, G.K. Lal “Experimental study of discharge mechanism in electrochemical discharge machining” International Journal of machine tool & Manufacturer 42 (2002) 1121-1127.

References