Basic Interview Questions 2017 For Mechanical Engineering

1. WHAT IS THE OTHER NAME OF MICROMETER AND VERNIER CALIPER

Ans: Micrometer’s other name is Screw Gauze and Vernier caliper’s other name is slide caliper.

2. How Cavitation can be eliminated in a Pump?

Cavitation means bubbles are forming in the liquid.
To avoid Cavitation, we have to increase the Pump size to One or Two Inch;
To increase the pressure of the Suction Head,or Decrease the Pump Speed.

3. Which pump is more efficient Centrifugal pump or Reciprocating pump?

Centrifugal pump.

Because flow rate is higher compared to reciprocating pump. Flow is smooth and it requires less space to install. Lower initial cost and lower maintenance cost.

4: State Laws of conservation of energy?

According to the laws of conservation of energy, “energy can neither be created nor be destroyed. It can only be transformed from one form to another.”

5. Explain the nomenclature of a 6203-ZZ bearing.

6 is the type code, which shows it is a single-row ball bearing, 2 is the series, means light, 03 is the bore, which is 17 mm and ZZ is the suffix meaning double shielded bearing.

6. What are differences between Welding and Brazing?

In Welding concentrated heat (high temperature) is applied at the joint of metal and fuse together. In Brazing involves significantly lower temperatures and does not entail the melting of base metals. Instead, a filler metal is melted and forced to flow into the joint through capillary action.

7. What is the difference between Blower and Fan?

Fan is an air pushing device. Either Axial or Centrifugal type systems are used to move the air in low pressure. It is rotated by a motor separately.

When the fan is a housing of blades and motor, then it called as Blower. It directs the air in a single path with high pressure.

8. What is the difference between Pipe and Tube?

Ex. Iron Pipe, Carbon Tube, Steel Tube etc.
Tube is defined by Outer diameter and Wall thickness (OD and WT). While Pipe is defined by Inner diameter (ID).
Tube is easily shaped by bending, where Pipe needs some mechanical work to shape it.
Tube is tight then Pipe.
Tube is applicable to non cylindrical sections like Square and Rectangular.

Example:

2 inch pipe have 2.375 inch outer diameter, where 2 inch tube have same 2 inch outer diameter.

9. What are the differences between Weight and Mass?

Mass is a measure of how much matter an object has. Mass is specified in Gram or Kilograms. Weight is a measure of how strongly gravity pulls on that matter. Force is measured in Newton’s.

F=m.g

Thus if you were to travel to the moon your weight would change because the pull of gravity is weaker there than on Earth but, your mass would stay the same because you are still made up of the same amount of matter.

10. What is the difference between Yield and Ultimate tensile strength?

The yield strength is reached when the material becomes Non – linear (that is non elastic) and takes a permanent set when load is released. Material stretches but does not break. Ultimate strength is when it breaks and is higher than yield strength.

11. What is the difference between Bolt and Screw?

The main difference was based on the load acting on it, and the size. For smaller loads, screws are enough but in case of greater-loads, bolts are to be used. In bolt we give centrifugal force or tangential force and screw we give axial force for driving.

12. Difference between TIG and MIG welding

Tungsten inert gas welding-non consumable electrode. MIG-Metal inert gas welding-uses consumable electrode.

13. What does CC Stand for?

CC is the abbreviated form of cubic centimeter. It is the unit by which the capacity of an engine is designated. It is the volume between TDC and BDC. It represents the quantity of fuel-air mix or exhaust gas that is pumped out in a single piston stroke. Alternatively it can represent the volume of the cylinder itself.

14. The Compression ratio of Petrol engine is always less than Compression Ratio of Diesel engine why?

Petrol is not self igniting , it needs spark to flame up in chamber. Where as diesel is self igniting in diesel engine , to attain that state it requires high temp and pressure. This temperature and pressure is more than what’s required in Petrol Engines by property of that fluid .

15. what is BHP?

Brake horsepower is the amount of work generated by a motor under ideal conditions. This work is calculated without the consideration of effects of any auxiliary component, that may slow down the actual speed of the motor. Brake horsepower is measured within the engines output shaft and was originally designed to calculate and compare the output of steam engines.

As per the conventions, 1 BHP equals to:

· 745.5 watts

· 1.01389 ps

· 33,000 ft lbf/min