Mechanical engineering interview questions and answers for freshers and experienced. Are you mechanical engineering student or have done mechanical engineering you must know the basic questions which are going to be asked in the freshers interview. Mechanical engineering is the one of the oldest and core branch of engineering. This is the some basic interview questions from all subjects of mechanical engineering.
Q 1.What is machine design?
Ans: Machine design has different definitions in different books it can be defined as (as per V B Bhandari )the integration of scientific principles, technical information and imagination to perform specific mechanical system with maximum economy and efficiency.
Q 2.What is the basic procedure of machine design?
Ans: 1.Market survey
2.Define specifications of product
3.Study alternative mechanisms for product and select proper mechanism.
4.Prepare general layout of configuration and select joining methods between individual
components of product.
5.Design individual components.
6.Prepare assembly and detail drawing.
Q 3. What is the function of bearing in?
Ans: To support the rotating shaft and confine its motion.
Q 4.What is the function of fastening screw?
Ans: To hold two or more machined parts.
Q 5.Define standardization in Mechanical engineering?
Ans: Standardization is the setting of universally accepted norms which describes products characteristics.
Q 6.What are the power transmitting elements?
Ans: Shafts, Gears, Belts, Pulleys, Clutches, Cams and chains.
Q 7.What are the types of keys?
Ans: Sunk key, Saddle key, Tangent Keys, Round keys, Splines.
Q 8.Describe the function of clutch?
Ans: When clutch is engaged, the clutch transmits maximum power from engine crankshaft to gearbox input shaft.
Q 9. What are the types of belts?
Ans : Flat belt, V belt, Circular Belt
Q 10. What are the general considerations in mechanical design?
Ans: 1. Types of loads
2.Selection of materials
3.Shape and size
4.Friction and lubrication
7.Use of standard parts
8.Motion of elements
10.Maintenance of element
11.Life of element
12.Weight of element.
13.Cost of element.
Q.11 What are the properties of material?
Ans: 1. Elasticity
Q.12 What is strength of material?
Ans : It is ability of material to resist the externally applied forces without fracture.
Q.12 What is elasticity?
Ans : Elasticity of material is the ability of material to regain its original shape and size after removal of applied external load.
Q.13 What is hardness?
Ans : It is resistance to scratch, abrasion or cutting.
Q. 14 Define ductility?
Ans : It is defined as the ability of material to deform to a greater extent before the sign of crack.
Q. 15 What is brittleness?
Ans : It is property of breaking of material with negligible deformation.
Q. 16 What is fatigue?
Ans : Material is subjected to repeated stresses or loading, it fails at stresses below the yield point stress. Such type of failure of material is called fatigue.
Q. 17 What are the selection criteria for materials?
Ans : 1.Availability of materials
2.Properties of materials
6.Reliability of materials
9.Cost of materials
Q.18 Classify engineering materials?
Ans :1. Metal and their alloys-Ferrous metals and Non ferrous materials.
2.Non metals- Rubber, Plastics, Woods, Glass.
Q.19 What is tolerance?
Ans : Tolerance is define as the permissible variation in the components dimensions.
Q.20 What is machine?
Ans : Machine is the combination of mechanism which is having fixed and moving links to perform specific function by using various forms of energy.
Q.21 Classify manufacturing processes?
Ans : 1.Machining processes
4.Surface finishing processes
Q.21 What is factor of safety?
Ans: In design stage it is necessary to provide sufficient reserve strength in case of an accident. This is achieved by factor of safety.
Factor of safety is defined as the ratio of failure load to working load.
Q.22 What is torque?
Ans: Torque is defined as force into perpendicular distance.
Q.23 What is power screw?
Ans: It is mechanical device used for converting rotary motion into linear motion and transmitting power.
Q.24 List out flexible drives?
Ans: Belt chain and rope are flexible drives.
Q.25 What are advantages and disadvantages of chain drives?
1.Can be use for long as well as short distances.
2. Chain drive have small overall dimensions than belt drives.
3.It is positive drive, minimum slippage.
4.Efficiency of drive is high it is about 97% to 98%.
5.Chains are easy to replace
6.Does not require initial tension.
1.Chain drives generate noise.
2.Chian drives require housing.
3.Chain drives are not suitable for non-parallel shafts.
Q.26 What are the different welding processes?
Ans: 1. Thermit welding
3.Electric arc welding
5.Electric resistance welding
Q. 27 What are different welding joints?
Ans: 1. Butt joints
a. Square butt joint
b. V-butt joint
c. U-butt joint
d. Double V-joint
e. V-joint with backing strip
a. Single transverse fillet weld
b. Double transverse fillet welds
c. Double parallel fillet welds.
Q. 28 What is coupling? Where do you use it?
Ans: Coupling is mechanical device that permanently joins two rotating shafts to each other.
Q.29 What is the difference between rigid and flexible coupling?
Ans: When the axes are co-linear or in the same line, rigid or flexible couplings are used. While the flexible coupling is capable of tolerating a small amount of misalignment between the shafts, there is no such provision in rigid coupling.
Q.30 What are the function of springs?
Ans: 1.Used to absorb shocks and vibrations e.g., vehicle suspension spring, railway buffer spring.
2.Used to store energy, e.g., springs used in clocks, toys, movie cameras.
3.Used to measure force, e.g., weighing balance
4.Used to apply force and control motion.
Q.31 What is the difference between clutch and coupling?
Ans: Coupling is the permanent connection between shafts while clutch can engage and disengage.
Q.32 What is the function of brake?
Ans: It is mechanical device, which is used to absorb the energy possessed by a moving system or mechanism by means of friction.
Q.33 What is the thermodynamics?
Ans: It is branch of science which deals with study of energy interaction and its impact on the properties of system.
It is branch of science which deals with study of 3E’s that is energy, equilibrium and entropy.
It is branch of science which deals with the conversion of disorganized form of energy into organized form of energy.
Q.34 What is thermodynamic system, surrounding and boundary?
Ans: System – Anything under consideration or it is control region in space over which our attention is focused.
Surrounding – Anything external to the system.
Boundary – Which separate system from surrounding.
Q. 35 What is the ideal equation of gas?
Ans: Pv = mRT
P – Absolute pressure
V – Volume
M – mass
R – characteristics gas constant
T – Absolute temp in K.
Q. 36 What triple point of water?
Ans: 273..16K or 0.01C
Q. 37 What triple point pressure of water?
Ans: 611.97 Pa
Q. 38 What is zeroth law of thermodynamics?
Ans: According to this law if body A is in thermal equilibrium with body ‘B’ and body ‘B’ is in thermal equilibrium with body ‘C’ separately. Then body A and C will be in thermal equilibrium with each other.
Q.39 What is work?
Ans: Work is said to be done by the system if sole effect on the things external to the system.
Q.40 What is adiabatic process?
Ans: It is the process in which there is no heat interaction between system and surrounding.
Q.41 What is heat?
Ans: It is form of energy interaction due to temperature
Q.42 What are the types of heat?
Ans: 1.Sensible heat – It is form of heat by the virtue of temperature difference.
2.Latent heat – It is form of heat which is required to cause the phase change.
Q.43 What is the first law of thermodynamics?
Ans: Energy can neither be created nor be destroyed rather it converts from one form of energy
Q.44 What is enthalpy?
Ans: It is amount of energy associated with the flowing fluid.
Q.45 What is nozzle?
Ans: It is mechanical device of variable passage which is use to increase the kinetic energy at the expanse of pressure.
Q.46 What is diffuser?
Ans: It is mechanical device of variable cross section which is use to decrease the velocity.
Q.47 What is turbine?
Ans: Turbine is a mechanical device in which energy is transfer from working fluid to rotor. In the case of turbine expansion of the working fluid takes place there for network output is positive.
Q.48 What is compressor or pump?
Ans: Both are work absorbing device in which energy transfer from rotor to working fluid.
Q.49 What is boiler?
Ans: It is mechanical device in which heat is absorb by the working fluid at constant pressure.
e.g. fire tube and water tube boiler.
Q.50 What is condenser?
Ans: Heat is rejected by the working fluid at constant pressure.
Q.51 What is entropy?
Ans: Generally it is measurement of degree of dis-order ness or randomness associated with the molecules.
e.g. boiling water, popcorn making etc.
Q.52 What is refrigeration effect?
Ans: It is amount of heat which is require to extract from storage space in order to provide and maintain lower temp than that of surrounding.
Q.53 What is refrigerant and examples of it?
Ans: It is working fluid or working substance which is use to extract the heat from the storage space.
e.g., R-11, R-12, R-22, R-134a, NH3.
Q.54 One ton of refrigeration is equal to?
Ans: 3.5 kw
Q.55 What is psychometric?
Ans: It is branch of science which deals with study of moist air.
Q.56 What is degree of freedom?
Ans: The minimum no of independent variable require to define the position or motion of system is known as degree of freedom.
Q.56 What is degree of freedom of spherical pair?
Q. 57 What is mechanical gear?
Ans: Generally positive drive which is used in power transmission.
Q.58 What are the types of gears?
Ans: 1.Spur gear, Helical gear, Bevel Gear, Worm gear, External gears, Internal gears.
Q.59 What is gear module?
Ans: It is the ratio of pitch circle diameter to no of teeth.
Q.60 What is need of gear train?
Ans: 1. Large center distance
2.Requirement of very high or very low velocity ratio.
3.Multiple velocity ratio are demanding.
Q.61 What are the different types of gear trains?
Ans: 1.Simple gear train
2.Compound gear train
3.Reverted gear train
4. Epicyclic gear train
5.Planetary gear train
Q.62 What is the function of mechanical flywheel?
Ans: It is device which is serve as reservoir to storage energy when supply of energy is more than requirement and release energy when requirement is more than supply.
Q.63 What is fluid?
Ans: A fluid is a substance that is having the ability to flow or deform continuously under the action of shear force.
Q.64 What is density?
Ans: Density is the ratio of mass per unit volume and its SI unit is Kg/m^3
Q.65 What is specific gravity of fluid?
Ans: Specific gravity is the ratio of density of fluid to the density of standard fluid. It is dimensionless quantity.
Q.66 What is specific weight?
Ans: Specific weight is the ratio of weight of the fluid per unit volume and its unit is N/m^3
Q.67 What is compressibility of fluids?
Ans: Whenever there is a change in volume or density with respect to pressure such fluids are compressible.
Q.68 What is viscosity?
Ans: Viscosity is defined as the internal resistance offered by one layer of fluid to the adjacent layer.
Q.69 What is the unit of viscosity?
Ans: 1.Dynamic viscosity – Ns/m^2 and,
2.Kinematic viscosity – m^2/s
Q.70 What is the main reason of surface tension?
Ans: Main reason of surface tension is the unbalanced cohesive forces. but,
With increase in temperature surface tension is decreases
At critical point surface tension is zero.
Q.71 What is capillarity in mechanical engineering?
Ans: It is the rise or fall of liquids when small diameter tube is insert in it.
Capillary rise is due to adhesion where as capillary fall is due to cohesion.
Q.72 What is pressure and its unit?
Ans: It is the ratio of normal force per unit area and its SI unit is Pa or N/m^2.
Q.73 What are the types of pressure as per Mechanical Engineering?
Ans: 1. Atmospheric pressure – It is the pressure exerted due to environmental air and it is measured by device known as barometer.
1 atm = 1.01325bar
2.Gauge pressure – Whenever pressures that which are going measure with respect to atmospheric pressure are known as gauge pressure.
3.Absolute pressure – Whenever pressures that are measured with respect to zero pressure line are known as absolute pressure.
4 Vacuum Pressure – Whenever pressures that are less than atmospheric pressure are known as vacuum pressure.
Q.74 Define pascals law?
Ans: Pascals law state that in static fluid pressure at point is equally distributed in all the directions.
Application of pascals law
Q.75 What is buoyancy force?
Ans: Whenever a body is either partially or completely submerged in fluid it will experience a force in vertically upward direction this force is known as buoyancy force.
Q.76 What is the principle of flotation in Mechanical engineering?
Ans: A body will float only when the weight of body is balanced by buoyancy force this is known as principle of flotation.