Unconventional Machine Process Set 12

Answer: upper and lower diamond guides

Explaination:
in wire-cut edm (wedm), the wire which is constantly fed from a spool, is held between upper and lower diamond guides. the guides are usually cnc-controlled and move in the x–y plane.

Answer: z-u-v axes

Explaination:
on most machines, the upper guide can move independently about the z–u–v axes, giving it the flexibility to cut tapered and transitioning shapes (example: square at the bottom and circle on the top).

Answer: resistivity

Explaination:
in the wire-cut edm process, water is commonly used as the dielectric fluid. filters and de-ionizing units are used for controlling the resistivity and other electrical properties.

Answer: flushing away the burr

Explaination:
apart from being used as a dielectric fluid, the water also helps in flushing away the debris from the cutting zone. the flushing also helps to determine the feed rates to be given for different thickness of the materials.

Answer: lesser cutting forces

Explaination:
the wire-cut edm process requires lesser cutting forces in material removal; hence it is generally used when lower residual stresses in the workpiece are desired.

Answer: true

Explaination:
if the energy/power pulse is relatively low (as in finishing operations), little changes in the mechanical properties of the material are expected due to residual stresses. the components which are not stress-relieved earlier can get distorted in the machining process.

Answer: true

Explaination:
in wedm process, the selection of process parameters is very crucial, as in some cases the workpiece undergoes significant thermal cycles the can be very severe. these thermal cycles can form recast layers and induce residual tensile stresses on the workpiece.

Answer: electro-thermal

Explaination:
electrically conductive materials are cut by wedm process by an electro- thermal mechanism. in the wedm process, the motion of the wire is slow. it is fed in the programmed path and material is removed from the workpiece accordingly

Answer: the wire-electrode and the workpiece

Explaination:
in wire-cut edm process, material removal takes place by a series of discrete discharges between the wire and the workpiece in the presence of a di-electric fluid. water is commonly used as the di-electric fluid.

Answer: tool-electrode

Explaination:
the di-electric fluid gets ionized in between the tool-electrode gap and hence, helps in creating a path for each discharge. because of these discharges, material is removed from the workpiece.

Answer: di-electric fluid

Explaination:
the area wherein discharge takes place gets heated to very high temperatures such that the surface gets melted and removed. the cut particles (debris) get flushed away by the continuously flowing dielectric fluid.

Answer: tool steels

Explaination:
wedm is a non-conventional process and is very widely used in tool steels for a pattern and die making industries. the process is also used for cutting intricate shapes in components used for the electric and aerospace industries.

Answer: zirconium

Explaination:
wire-cut edm is used for cutting:

Answer: true

Explaination:
this process is used in the following areas:

Answer: true

Explaination:
following are the few areas where wedm process is used:

Answer: 4

Explaination:
the subsystems of wire-edm process are:

Answer: conventional edm

Explaination:
the power supply and the di-electric system used in wedm is very similar to that of the conventional edm. the main difference lies only in the type of di-electric used.

Answer: cut complex outlines

Explaination:
in wire-cut edm, a moving wire is used to cut complex outlines and fine details in the required workpiece. the wire is wound on a spool and is kept in constant tension

Answer: die-sink edm

Explaination:
wire electric discharge (ed) machining is based on the same principle as die-

Answer: electrode used for the machining

Explaination:
in the die-sink edm method the electrode has the same shapes as the wished machining results. in the wire cut edm method the electrode is a moving wire made from some electrically conducting material. the workpiece is cut with the electrode wire.

Answer: electric current

Explaination:
while machining a high electric current passes through the dielectric fluid and heats the workpiece surface from a very small area. the corresponding workpiece area melts and what is left, is a small round cavity. the cavity size depends on the electric current and potential.

Answer: the workpiece and the electrode wire

Explaination:
the distance between the electrode wire and the workpiece is called a sparking gap. the electrode produces shapes that are a sparking gap dimension larger than the programmed shape through which the electrode wire passes.

Answer: the wire radius plus the sparking gap width

Explaination:
the absolute minimum inner corner radius is the wire radius added with the sparking gap width. therefore during machining, the shapes produced have larger dimensions as compared to the shapes mentioned in the program.

Answer: electrode wire

Explaination:
the electrode wire moves between two coils with a moderate speed. the part of the wire that actually machines the workpiece is constantly changing. there is no time for the wire to heat up.

Answer: electrical conductivity

Explaination:
as the electrode wire does not get heated during machining, the problems with electrode wear are not an issue like in the case of die-sink ed machining and it is possible to use wire cut edm also for materials with high melting ranges. the material hardness sets no restrictions. the only restriction is that the material needs to be electrically conductive.