## Posted tagged ‘interview questions’

### Mechanical Engineering Interview Questions

September 23, 2011
• What is Heat rate of a Power plant?

Heat rate is a measure of the turbine efficiency. It is determined from the total energy input supplied to the Turbine divided by the electrical energy output.

• The highest value of Thermal conductivity is expected for

a.) Solid ice   b.) Melting ice c.) Water d.) Boiling water.

Give the Thermal conductivity value.

Solid Ice – 3.48 W/mK

Melting Ice thermal conductivity value is low because temperature is less.

Water’s Thermal conductivity value is 2.18 W/mK.

• What is a Hydrostatic system?

Hydrostatics is the study of ﬂuid bodies that are

• At rest
• Moving suﬃciently slowly so there is no relative motion between adjacent parts of the body

For hydrostatic situations

• There are no shear stresses
• There are only pressure forces that act perpendicular to any surface.

It’s a closed loop hydraulic systems. It comprises of motor and pump. Here pump supplies energy to motor and motor gives return energy to pump supply.

• If you heat a piece of steel with a hole in the center will the diameter of the steel get bigger or smaller?

It gets bigger.

(Example: Always the bearings are heated first for new installation in a shaft.)

• 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.

• How to find a Ductile-Brittle Transition Temperature in metals?

The point at which the fracture energy passes below a pre-determined point for a standard Impact tests. DBTT is important since, once a material is cooled below the DBTT, it has a much greater tendency to shatter on impact instead of bending or deforming.

• What is Hydrodynamic Cavitation?

Hydrodynamic cavitation describes the process of vaporization in a constrained channel at a specific velocity.

Bubble generation and Bubble implosion which occurs in a flowing liquid as a result of a decrease and subsequent increase in pressure.

### Entry Level Mechanical Engg Jobs Interview Questions

September 20, 2011

1) Difference between Performance and Efficiency?

· The accomplishment of a given task measured against preset known standards of accuracy, completeness, cost, and speed is called as Performance.

· Efficiency is defined as the input given and the work obtained from that input like money, time, labour etc. It’s the main factor of productivity.

2) What is the difference between Impact Force & Sudden Force?

· An impact is a high force or shock applied over a short time period when two or more bodies collide.

· A force which applies on the body (material) suddenly is known as sudden force.

3) Difference between Antifriction Bearing and Journal Bearing

Generally, journal bearings have higher friction force, consume higher energy and release more heat, but they have larger contact surface, so normally used in low speed high load applications. In anti friction bearings friction is less.  One object just rolls over each other.

4) What is a Cotter joint?

A cotter joint is used to connect rigidly two co-axial rods or bars which are subjected to axial tensile or compressive forces. Here shaft is locked in place by a smaller pin that passes through the side of the lug and partly or completely through the shaft itself. This locking pin is named as cotter.

5) What is difference between Hardness and Toughness?

· Toughness is the ability of a material to absorb energy.

· Hardness is the ability of a material to withstand wear.

6) What is the difference between Toughness, Hardness and Strength?

· Toughness is the ability of a material to absorb energy.

· Hardness is the ability of a material to withstand wear.

· Strength is generally withstanding stresses, fatigue etc.

7) What is the difference between Strength and Stamina?

· Strength is capability over a short length of time.

· Stamina is the ability to keep going continuously.

### Latest Interview Questions & Answers

September 16, 2011

1. What is Auto Dosing?

Auto dosing is an automated system of feeding the equipment with liquid products. It is the ideal way to ensure the correct calibrated dose at the right time every time in auto.

2. Difference between Codes, Standards and Specifications?

• Code is procedure of acceptance and rejection criteria.
• Standard is accepted values and compare other with it.
• Specification is describing properties of any type of materials.

3.  Difference between Strainer and Filter

Strainer for coarse size, Filter is more accurate than Strainer.

4. What are differences between Welding & 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.

5. What does a pump develops? Flow or Pressure

A pump does not create pressure, it only creates flow. Pressure is a measurement of the resistance to flow.

6. Which is heavier 1kg of Iron or 1kg of Cotton? and why?

Both of them have same weight. The only difference is the volume of Iron is small compared to Cotton.

7. What will be the position of Piston Ring?

In 180 degree angle the Top ring, Second ring and Oil ring are fixed. Position the ring approximately 1 inch gap below the neck.