WorksheetsNCM_Unit-3 Test
Total questions: 20
Worksheet time: 22mins
Which one the following statements is true for Electrical Discharge machining (EDM)?
i. The material removal takes place due to the melting and evaporation of the workpiece material.
ii. Any electrical conductor can be machined by this method.
iii. Some light oil like transformer oil or kerosene oil is used as dielectric.
Only i
i & ii
i, ii & iii
ii & iii
Which one of the following statements is not true in case of EDM?
Erosion takes place both on work piece and tool.
Gap between tool and work piece is controlled by servo mechanism.
The size of impression on the work piece surface is exactly same as that of electrode (tool).
The electrode (tool) is made of graphite or copper.
Feed to the electrode during EDM is given
to maintain constant velocity of dielectric flow in the IEG
to maintain constant IEG
to maintain constant current density
none of these
During EDM, the temperature developed at the point of spark is of the order of
2,000°C
6,000°C
10,000°C
14,000°C
In EDM the metal removal is carried out by
fracture of work material due to impact of grains
electrolysis
melting and vaporization
none of the above
Deionized water is used as dielectric in
wire-EDM
electric discharge grinding
electric discharge diamond grinding
Electron Beam Machining
Preferable tool properties in EDM are
High electrical conductivity, low thermal conductivity
low electrical conductivity, High thermal conductivity
High electrical conductivity, High thermal conductivity
low electrical conductivity, low thermal conductivity
In EDM the material of the tool is
Satellite
Diamond
Carbide
High speed steel
Copper
Undesirable characteristic of graphite electrode is
Higher TWR
Poor surface finish
Brittleness
All of the above
EDM is not suitable for machining of
Very hard metals
Glass
Fragile metallic components
None of the above
Stratified wires are used so that they can
withstand more mechanical forces
carry more heat energy
both of these
none of these
Which of the following is used as dielectric medium in EDM
tap water
kerosene
NaCL solution
KOH solution
Wire electric discharge (ED) machining is based on the same principle as that of _____
hydro-dynamic EDM
die-sink EDM
polar EDM
non-conventional EDM
Which of the following component of the wire cut EDM machine does not get heated?
Workpiece
Electrode wire
Di-electric fluid
Coils
The electrode wires are usually made form _____
graphite
iron
nickel
brass
Wire-cut EDM can cut plates of thickness upto _____
50mm
100mm
300mm
500mm
Electrically conductive materials are cut by WEDM process by _____ mechanism.
thermal
electro-thermal
electro-dynamic
fused metal
In WEDM, the wire is held tight between_____
upper and lower nozzles
upper and lower diamond guides
upper and lower groves in the handle
upper and lower pulleys
Which of the following material properties sets restrictions to use wire cut EDM?
Material type
Melting point
Material hardness
Electrical conductivity
During wire cut EDM, the size of the cavity produced by the wire while machining depends upon ____
material of the workpiece
di-electric fluid used
wire material
electric current
