This set of Manufacturing Processes Multiple Choice Questions & Answers (MCQs) focuses on “Wire-cut EDM – 8”.
1. Submerged machining is extremely useful for applications that generally have_____
a) poor flushing conditions
b) intricate shapes
c) tapered sections
d) good weldability
Explanation: Submerged machining is extremely useful for applications that generally have poor flushing conditions. Applications where poor flushing conditions exist are numerous.
2. Submerged machining is used for ____
a) cutting small taper angles
b) tiny workpieces
d) workpieces with no undercuts
Explanation: Some applications and examples where submerged machining is more practical would be cutting large taper angles, tall workpieces, laminations, tubes, irregular shaped parts, workpieces with undercuts and cutting very close to the edge of the workpiece.
3. There is a greater risk of breaking a wire if ______
a) temperature of the wire is too high
b) larger taper angles are to be cut
c) the flush is not set properly
d) there is an inadequate flow of di-electric fluid
Explanation: There is a greater risk of breaking a wire if the flush is not set properly or if too much power is used. This condition is greatly reduced when cutting the part submerged.
4. How many of the following processes does not need submerged machining capabilities?
– starting a cut from the edge of a workpiece
-slicing a tube
-slicing a bar stock
-starting a cut from a large diameter start hole.
Explanation: When starting a cut from the edge of a workpiece, cutting a form tool, slicing a tube or bar stock, or starting a cut from a large diameter start hole, is a slower process without submerged machining capabilities.
5. When parts with existing openings in them must be cut, conventional flushing produces _____
a) air pockets
b) unnecessary tapers
d) poor flushing
Explanation: When parts with existing openings, slots or cross holes in them must be cut, conventional flushing produces air pockets and results in reduced performance or wire breaks. Submerged machining provides stable cutting of these parts.
6. When it is not possible to have the flushing nozzles close to the top or bottom of the workpiece _____ machines may require constant adjustment of the top and bottom flush.
a) submerged type
b) splash flush
c) rigid flush
d) stock flush
Explanation: When it is not possible to have the flushing nozzles close to the top or bottom of the workpiece, splash flush machines may require constant adjustment of the top and bottom flush. When machining submerged, you can adjust the flush once and forget it.
7. Which of the following is not the benefit of submerged cutting?
a) improved accuracy
b) better surface finish
c) Thermal stability
d) no wire breakage
Explanation: Benefits of submerged cutting are:
• Enhanced thermal stability of the entire set up
• Accurate skim cuts
• Better surface finish
• Improved accuracy.
8. Submerged cutting helps cutting the workpieces without hampering the flush.
Explanation: Cutting round stock or tubing presents a combination of adverse effects. Submerged cutting can efficiently cut these jobs without the flush being impaired.
9. Which of the following is not the effect of less maintenance of the wire cut EDM machines?
a) Wire breaks
b) Lines in the part
c) Lowered time to complete the job
d) Rough surfaces
Explanation: the lack of maintenance will lead to slower cutting speeds, size inaccuracy, lines in the part, wire breaks, a rougher surface finish, and (eventually) a service call. Maintenance of Wire EDM machine (or any EDM machine) usually consumes twenty to thirty minutes a week or less.
10. In how many of the following applications, wire cut EDM can be used?
– Manufacturing of progressive, blanking and trim dies
– Extrusion dies
– Cutting difficult to machine materials like hastaloy, inconel and titanium
– Cutting narrow slots and keyways
– Manufacturing of parts where burrs can’t be tolerated.
Explanation: Wire cut EDM has a broad range of applications that are continuing to grow. Some of them are listed below:
. Parts with complex geometry’s
. Parts requiring “tenths” tolerances
. Parts where burrs can’t be tolerated
. Thin or delicate parts that are susceptible to tool pressure
. Progressive, blanking and trim dies
. Extrusion dies
. Narrow slots and keyways
. Mold components
. Tooling for forging, or injection molding operations.
. Medical and dental instrumentation
. Cutting hardened materials such as carbide, C.B.N. and P.C.D.
Cutting difficult to machine materials like hastaloy, inconel and titanium
. Aerospace, defense and electronic parts
. Prototypes parts
Form tools and inserts
Electrodes (graphite or copper) for vertical EDM.
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