1.
State the principle of chemical machining process?
In chemical machining process,
material is removed from the workpiece through a controlled etching or chemical
attack of the workpiece material.
2. Name the etchants used in chemical
machining process?
a. Caustic Soda
b. Hydrochloric acid
c. Nitric acid
d. Iron carbide.
3. Name some of the maskants used in
CHM?
a. Butyl rubber
b. Neoprene rubber
c. Polymers
d. Polethylene, etc.,
4. Write the principle of ECM process?
ECM is
based on the principle of Faraday’s laws of Electrolysis and reverse
electroplating. In this process, the work piece is connected to positive
terminal (anode) and the tool is connected to negative terminal (cathode). When
the current is passed, the workpiece loses metal and the dissolved metal is
carried out by circulating an electrolyte between the work and tool.
5. What are the requirements of tool
materials in ECM process?
a. It should be conductor of
electricity.
b. It should be chemically inert to the
electrolyte.
c. It should be easily machinable.
6. What are the factors to be
considered while designing the tool.?
a. Determine the tool shape, so that
the desired shape of the job is obtained under existing machining conditions.
b. Design the tool by considering the
electrolyte flow, insulation strength and fixing arrangements.
7. State the function of electrolyte
used in ECM process?
a. It carries the current between the
tool and the work piece.
b. It cools the cutting zone which
becomes hot due to the flow of high current.
c. It removes products of machining
from the cutting zone.
8. What are essential characteristics
of an electrolyte used in ECM process?
a. It should be good conductor of
electricity.
b. It should have non- corrosive
property
c. It should have low viscosity and
high specific heat.
d. It should be non-toxicity and
chemical stability.
9. What are materials used for tools in
Electro chemical Machining?
Most commonly used tool materials
are copper, brass, titanium, copper- tungsten and stainless steel when the
electrolyte is made of sodium or potassium.
The other materials which can be
used as tool materials are aluminum. Graphite, bronze, platinum, tungsten
carbide.
10.
What
are the advantages of ECM?
a. Metal removal rate is high compared
to conventional machining process.
b. Wear and tear of the tool is
negligible.
c. The machined work surface is free of
stresses.
d. No cutting forces are involved in
the process.
e. High surface finish of the order 0.2
to 0.8 microns can be obtained.
11.
What
are the disadvantages of Electro Chemical Machining process?
a. Non- conducting materials cannot be
machined.
b. Initial investment is quite high.
c. More space is required.
d. Consumption of power is high.
12.
List
the applications of ECM process? It is used for
a. Machining complicated profiles
b. Drilling small deep holes.
c. Machining of hard materials and heat
resistant materials.
d. Machining of cavities and holes of
irregular shapes.
13.
What
are the limitations of ECM process?
a. Sharp internal corners cannot be
obtained. Tool design is very complicated and it requires cut and try method to
achieve the final shape.
b. Post machining cleaning is needed to
reduce the corrosion of the work piece.
14.
List
the advantages of Electro Chemical Grinding (ECG) process/
a. Tool wear is negligible. So, the
life of the grinding wheel is increased.
b. Good surface finish is obtained.
c. Burr free and stress free components
are produced.
d. As compared to conventional
grinding, a very little cutting force is applied to the work piece.
15.
List
the disadvantages of ECG process?
a. Initial cost is high.
b. Power consumption is high.
c. Metal removal rate is lower than
conventional grinding.
d. Non- conducting materials cannot be
machined.
16.
What
is the difference between ECG and conventional grinding?
In conventional grinding process,
metal is removed from the workpiece by using grinding wheel.
In electrochemical grinding process,
the work is machined by the combined action of electrochemical effect and
conventional grinding operation.
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