Transcript Electro-machining

PROPERTIES AND SELECTION OF MATERIALS
“ELECTRO MACHINING”
Presented by:
Presented to:
MUDIT RAJ YADAV 2008AMD3110
DEPTT. OF APPLIED MECHANICS
IIT DELHI
PROF. M.P. GURURAJAN
DEPTT. OF APPLIED MECHANICS
IIT DELHI
ELECTRO MACHINING
ELECTRO DISCHARGE
MACHINING(EDM)
ELECTRO CHEMICAL
MACHINING(ECM)
ELECTRO DISCHARGE MACHINING
(EDM )
ELECTRO CHEMICAL MACHINING (ECM)
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Electrical energy is use to cut material
to final shape. (SPARK EROSION
PROCESS).
When a difference of potential is
applied between two conductors
immersed in a dielectric fluid. Fluid
will ionize, if the potential diff. reaches
a high enough value and a spark will
occur.
If both the electrodes are of same
material then +ve one (anode, work
piece) will have more erosion.
A gap of 0.01 to 0.05 mm is
maintained, it governs the MRR
Current vary from 0.5 to 400 amp
Voltage 40-300 V DC
Fluid is pumped with a pressure of 2
kg/cm2.
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Electrical energy is use to cut material
to final shape (No spark)
In this process an electrolytic cell is
formed by the anode (work piece) and
cathode (tool) in the midst of a flowing
electrolyte.
Due to electrolytic process at the
cathode, -ve ions are released which
combine with the metal ion of anode
to form insoluble metal hydroxides.
Thus the metal is mainly removed in
the form of slugs and precipitates
This process is reverse of electro
plating but the metal is pumped in the
flowing electrolyte before it gets stuck
on the tool surface
Gap 0.01-0.7 mm
voltage D.C. supply(5-30 volts)
current of order 50-40000 amp
Fluid pressure =14 kg/cm2
CIRCUIT DIAGRAM
SPARK GENERATION
Sparking time period is of order=100 micro-sec
VARIATION OF MRR WITH DIFFERENT FACTORS
FEATURES OF EDM
Used for:• Super alloys
• Ti
• Steels
Fluids:• Paraffin with
• White spirit or
• Transformer oil
Tool materials:• Graphide
• Cu
• Cu-Wc
Applications:• Dies, punch
• Aircraft industry-fuel injector, nozzles
• To make holes in turbine blades
Change in properties:• Residual stresses
• Plastic deformation may occur
• Fine cracks in machined area
(2)ELECTRO CHEMICAL MACHINING
FEATURES OF ECM
Used for:(>400BHN)
• Ni alloys
• Ti alloys
• WC alloys
Fluids:• Natural salts
• Acids
• Alkalis
Tool materials:• Brass
• Cu
• Steels
Applications:• Profiled cavity
• Carbide tools
• Dies, punch
• Fuel injector, nozzles
• To make holes in turbine blades
Change in properties:- (No spark)
• So no metallurgical change (temp about 40100 C)
No change in properties like
• Melting point
• Composition
• Hardness, toughness, brittleness etc
CONCLUSIONS
•Both used electrical energy as source.
•Both processes are highly précised and modern techniques of machining.
•Both are used for machining of hard materials(>2000BHN ).
•Change in properties are negligible or none.
•But can be used for electric conductor materials only.
•Both can produces complex shape.
THANK YOU