# Advanced Machining Questions and Answers – ECM-Theory of ECM

This set of Advanced Machining Processes Interview Questions and Answers for experienced people focuses on “ECM-Theory of ECM”.

1. What is the value of the current density used in Electrochemical machining?
a) 0.01 – 0.4 A/mm2
b) 0.5 – 5 A/mm2
c) 6 – 15 A/mm2
d) 20 – 50 A/mm2

Explanation: High current densities, which range between 0.5 – 5 A/mm2 are used in ECM.

2. What are the values of voltages used in ECM?
a) 1 to 8 V
b) 10 to 30 V
c) 40 to 80 V
d) 90 to 110 V

Explanation: Low voltages, ranging between 10 to 30 V are used in Electrochemical machining.

3. How does the current pass between the two electrodes in ECM?
a) Electrolytic solution
b) Direct contact of electrodes
c) All of the mentioned
d) None of the mentioned

Explanation: Current passes through the solution of electrolyte, which fills the gap between the electrodes.

4. What is the value of velocity with which, electrolyte flows in the inter electrode gap?
a) >1 m/s
b) >3 m/s
c) >5 m/s
d) >10 m/s

Explanation: The velocity of the electrolytic solution must be greater than 5 m/s, in order to intensify the mass and charge transfer.

5. Of the following, electrolyte removes which of the dissolution products?
a) Metal hydroxides
b) Heat
c) Gas bubbles
d) All of the mentioned

Explanation: Electrolyte removes the dissolution products such as metal hydroxides, heat and gas bubbles formed in the inter electrode gap.
Sanfoundry Certification Contest of the Month is Live. 100+ Subjects. Participate Now!

6. State whether the following statement is true or false regarding the theory of ECM.
“Application of P.D (potential difference) lead to occurrence of several reactions.”
a) True
b) False

Explanation: When P.D (potential difference) is applied, different reactions occur at anode and cathode.

7. Which of the following reactions takes place at the electrodes?
a) Generation of hydrogen
b) Dissolution of iron
c) Dissolution of NaCl
d) All of the mentioned

Explanation: All the reactions mentioned above, take place at different electrodes in ECM.

8. Which of the following reaction takes place at anode?
a) Generation of hydrogen
b) Dissolution of iron
c) Generation of hydroxyl ions
d) None of the mentioned

Explanation: At anode, dissolution of Fe takes place in the process of ECM.

9. Which of the following reactions take place at cathode?
a) Generation of hydrogen
b) Dissolution of iron
c) Dissolution of NaCl
d) All of the mentioned

Explanation: At cathode, generation of hydrogen takes place in the process of ECM.

10. Positively charged particles (cations) move towards which electrode?
a) Anode
b) Cathode
c) Anode & Cathode
d) None of the mentioned

Explanation: Positively charge particles are directed towards the cathode, which is negatively charged.

11. Negatively charged particles (anions) move towards which electrode?
a) Anode
b) Cathode
c) Anode & Cathode
d) None of the mentioned

Explanation: Negatively charged particles are directed towards the anode, which is positively charged.

Sanfoundry Global Education & Learning Series – Advanced Machining.

To practice all areas of Advanced Machining for experienced people attending interviews, here is complete set of 1000+ Multiple Choice Questions and Answers.

If you find a mistake in question / option / answer, kindly take a screenshot and email to [email protected]