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.
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.
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.
Ans: To support the rotating shaft and confine its motion.
Ans: To hold two or more machined parts.
Ans: Standardization is the setting of universally accepted norms which describes products characteristics.
Ans: Shafts, Gears, Belts, Pulleys, Clutches, Cams and chains.
Ans: Sunk key, Saddle key, Tangent Keys, Round keys, Splines.
Ans: When clutch is engaged, the clutch transmits maximum power from engine crankshaft to gearbox input shaft.
Ans : Flat belt, V belt, Circular Belt
Ans: 1. Types of loads
2.Selection of materials
3.Shape and size
4.Friction and lubrication
5.Operational safety
6.Machine availability
7.Use of standard parts
8.Motion of elements
9.Production quantity
10.Maintenance of element
11.Life of element
12.Weight of element.
13.Cost of element.
Ans: 1. Elasticity
2.Plasticity
3.Toughness
4.Resilience
5. Strength
6.Stiffness
7.Ductility
8.Malleability
9.Brittleness
10.Hardness
11.Fatigue
12.Creep
Ans : It is ability of material to resist the externally applied forces without fracture.
Ans : Elasticity of material is the ability of material to regain its original shape and size after removal of applied external load.
Ans : It is resistance to scratch, abrasion or cutting.
Ans : It is defined as the ability of material to deform to a greater extent before the sign of crack.
Ans : It is property of breaking of material with negligible deformation.
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.
Ans : 1.Availability of materials
2.Properties of materials
3.Working environments
4.Physical attributes
5.Performance requirements.
6.Reliability of materials
7.Safety factor
8.Manufacturing considerations
9.Cost of materials
Ans :1. Metal and their alloys-Ferrous metals and Non ferrous materials.
2.Non metals- Rubber, Plastics, Woods, Glass.
Ans : Tolerance is define as the permissible variation in the components dimensions.
Ans : Machine is the combination of mechanism which is having fixed and moving links to perform specific function by using various forms of energy.
Ans : 1.Machining processes
2.Joining processes
3.Forming processes
4.Surface finishing processes
5.Hardening processes
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.
Ans: Torque is defined as force into perpendicular distance.
Ans: It is mechanical device used for converting rotary motion into linear motion and transmitting power.
Ans: Belt chain and rope are flexible drives.
Ans: Advantages
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.
Dis advantages
1.Chain drives generate noise.
2.Chian drives require housing.
3.Chain drives are not suitable for non-parallel shafts.
Ans: 1. Thermit welding
2.Gas welding
3.Electric arc welding
4.Forge welding
5.Electric resistance welding
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
2.Fillet joints
a. Single transverse fillet weld
b. Double transverse fillet welds
c. Double parallel fillet welds.
Ans: Coupling is mechanical device that permanently joins two rotating shafts to each other.
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.
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.
Ans: Coupling is the permanent connection between shafts while clutch can engage and disengage.
Ans: It is mechanical device, which is used to absorb the energy possessed by a moving system or mechanism by means of friction.
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.
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.
Ans: Pv = mRT
P – Absolute pressure
V – Volume
M – mass
R – characteristics gas constant
T – Absolute temp in K.
Ans: 273..16K or 0.01C
Ans: 611.97 Pa
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.
Ans: Work is said to be done by the system if sole effect on the things external to the system.
Ans: It is the process in which there is no heat interaction between system and surrounding.
Ans: It is form of energy interaction due to temperature
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.
Ans: Energy can neither be created nor be destroyed rather it converts from one form of energy
Ans: It is amount of energy associated with the flowing fluid.
Ans: It is mechanical device of variable passage which is use to increase the kinetic energy at the expanse of pressure.
Ans: It is mechanical device of variable cross section which is use to decrease the velocity.
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.
Ans: Both are work absorbing device in which energy transfer from rotor to working fluid.
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.
Ans: Heat is rejected by the working fluid at constant pressure.
Ans: Generally it is measurement of degree of dis-order ness or randomness associated with the molecules.
e.g. boiling water, popcorn making etc.
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.
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.
Ans: 3.5 kw
Ans: It is branch of science which deals with study of moist air.
Ans: The minimum no of independent variable require to define the position or motion of system is known as degree of freedom.
Ans: Three
Ans: Generally positive drive which is used in power transmission.
Ans: 1.Spur gear, Helical gear, Bevel Gear, Worm gear, External gears, Internal gears.
Ans: It is the ratio of pitch circle diameter to no of teeth.
Ans: 1. Large center distance
2.Requirement of very high or very low velocity ratio.
3.Multiple velocity ratio are demanding.
Ans: 1.Simple gear train
2.Compound gear train
3.Reverted gear train
4. Epicyclic gear train
5.Planetary gear train
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.
Ans: A fluid is a substance that is having the ability to flow or deform continuously under the action of shear force.
Ans: Density is the ratio of mass per unit volume and its SI unit is Kg/m^3
Ans: Specific gravity is the ratio of density of fluid to the density of standard fluid. It is dimensionless quantity.
Ans: Specific weight is the ratio of weight of the fluid per unit volume and its unit is N/m^3
Ans: Whenever there is a change in volume or density with respect to pressure such fluids are compressible.
Ans: Viscosity is defined as the internal resistance offered by one layer of fluid to the adjacent layer.
Ans: 1.Dynamic viscosity – Ns/m^2 and,
2.Kinematic viscosity – m^2/s
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.
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.
Ans: It is the ratio of normal force per unit area and its SI unit is Pa or N/m^2.
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.
Ans: Pascals law state that in static fluid pressure at point is equally distributed in all the directions.
Application of pascals law
1.Hydraulic lift
2.Hydraulic brake
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.
Ans: A body will float only when the weight of body is balanced by buoyancy force this is known as principle of flotation.
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