My Engineering Services Interview (Mechanical Engineering)

Ms. Chokila Iyer’s board interviewed me on 21st May 2007. I was the very first candidate to be interviewed this year. I was wearing a navy blue trouser and an off-white shirt with a matching tie of blue color with red dots. The helper opened the door and told me to go into the boardroom. I stopped near the door and my eyes met the chairman’s. She indicated me to come in. I went in and wished the members after which the chair indicated me to sit down. I thanked her and took my seat.
(for sake of simplicity CM stands for chairman Ms. Chokila Iyer, M1, M2 and M3 represent the other three male members present)
CM: Mr. Tirumala, I see from your profile that you have some work experience. Why did you leave your job?
Tiru: I left the job to prepare for civil services ma’m.
CM: I see, so you left the job to prepare for civil services. Anyway, I guess you would have come here by train. Am I correct?
Tiru: No madam, actually I am currently staying at Delhi and didn’t come from my hometown.
CM: Anyway, you must have traveled by train sometime. So I want to know whether you have observed lately that concrete sleepers are replacing the wooden sleepers being used earlier. What do you think about it? What is the advantage of concrete over wood?
Tiru: Madam, wood (lignum vitae) absorbs moisture and slowly loses its strength. India, being a tropical country, receives a lot of rainfall and this proves detrimental to life of wooden sleepers. Concrete sleepers do not have this problem.
CM: OK, thinking from environment point of view, what do you feel?
Tiru: Wood is renewable madam, as specific trees can be grown to meet the requirements but the metal such as iron used in reinforced concrete cannot be replaced, once used.
CM: You might be reading newspapers. What do you think about global warming? Do you think people are concerned?
Tiru: Yes madam, Global warming has taken up serious proportions now and it’s high time we take hard decisions to stop it. And yes, people are now very concerned which I feel is very correct. We now hear every other day about Green peace, Kyoto protocol, Carbon trading etc.
CM indicates to other members that she has finished asking questions and other members can now ask questions.
M1: So, I see that your hobbies are blogging and reading books. Don’t you think these two are contradictory?
Tiru: No sir, in fact I believe to be a good blogger or writer a person has to read a lot of books. The books give man perspectives on various issues. The books stimulate thinking and only then ideas come out which become material for blogging or writing.
M1: Do you write blogs online?
Tiru: yes sir, I maintain three blog sites. (I tell the details of my blog sites and what I write in them)
M2: You initially worked with Wipro. What were you doing there?
Tiru: Sir I was working at Wipro fluid power. (I explain my roles and responsibilities)
M2: Tirumala, what is the relation between global warming, ozone hole and the refrigerators we use?
Tiru: Sir, ozone hole is a side effect of pollution and global warming. Some refrigerants which contain chlorine in them e.g. Freon group react with ozone and break them into oxygen and this leads to formation of ozone hole. That is the reason why now a days such refrigerants are being phased out and we are moving towards chlorine free refrigerants like R134-a.
M2: But do you know that ozone hole has formed over Antarctica. Why has it not formed over US, Europe or India?
Tiru: Sir, it is not that the effect of pollution or global warming should be felt in the immediate vicinity. There are surface winds which moves all over the world and even the ocean currents move. Therefore, the effect of US’s pollution might be manifested anywhere in the world. This is true of any place and in any case sir, it is good that the hole has formed over Antarctica. Had it formed on our country, we would have been in trouble.
CM: Tirumala, you were working earlier. I see that you last worked as a senior design engineer at Eaton industries before leaving it. What were you doing there?
Tiru: (I explained my complete job profile which involved product development in hydraulics field)
M2: So you worked on gear pumps too. What type of gear do they use in gear pumps? What is the profile? Is it same as the one in industry?
Tiru: Yes sir, we too use involute profile but with a positive addendum correction.
M2: Can you show me how an involute profile is generated? Please draw it on the paper.
Tiru: (I draw it and show), Sir, this is the base circle and this is the generating line that rolls without slipping on it. Any point on it traces the involute curve.
M2: How do you manufacture involute gears?
Tiru: Sir, for mass production, we use hobbing. However, we can also go for simple shaping or milling too. But they are slow.
M2: What is the difference between hobbing and gear shaping?
Tiru: Sir, the principal is same except that the tool shape in hobbing is such that the cutting motion is continuous. The teeth are wound over a cylinder.
M2: Ok, can you tell me something about hydraulic pumps? What is a positive displacement pump and is there anything called negative displacement pump?
Tiru: Sir, there is nothing called negative displacement pump. We have positive or non-positive displacement pumps. The difference lies in the principle of operation. The positive pumps generate pressure by reducing the volume occupied by the fluid. The non-positive ones work on generating the pressure head by consuming the kinetic head as per Bernoulli’s equation.
M3: I see that you were also into bodybuilding and power lifting? What is the difference and use of these sports?
Tiru: (I explain)
M2: But bodybuilding is not a team sport. Don’t you think it is better to play team sport to develop team spirit?
Tiru: (I defend and accept the view of the member)
M3: Can you compare yoga with bodybuilding?
Tiru: (I compare and enumerate advantages and disadvantages of both)
M3: Regarding the question madam asked about wooden and concrete sleepers, I want to ask you one more thing. What is the advantage of wood over concrete?
Tiru: I don’t know exactly sir.
M3: What do you think about vibrations?
Tiru: Yes sir, wood is a better damper than concrete.
M3: So what should be done if we use concrete?
Tiru: Then we have to introduce dampers sir.
M3: Yes, we have to use dampers. Good. As you have worked in the field of fluid power, can you define what is a fluid?
Tiru: An ideal fluid is one which doesn’t offer any shear resistance i.e. no shear strain gradient is formed when subjected to shear stress. However, generally fluids form a strain gradient based on Newton’s law of viscosity as they deviate from ideal.
M3: Is air fluid?
Tiru: Yes sir, Air is a fluid.
The members indicate to the chairman that they have finished asking questions.
Chairman: Thank you Mr. Tirumala. Your interview is now over. You may leave now.
Tiru: thank you madam, thank you sirs.

I got up and walked out of the room. The interview lasted around 20 minutes.


Tiru
(I got through this exam. All India 38th Rank. The results came on 8th June 2007)