Technical Questions For Interview Mechanical Subject wise

Type of technical questions asked will be from basics. Most of the time your favorite subjects will be asked and they start from there.

Strength of Materials

• What do you mean by uniform strength in a beam?

• What is the difference between pure shear and simple (normal) shear?

• Is it possible that a decrease in the area gives a decrease in stress?

• Whether shear stresses are always parallel to shear forces?

• By which experiment, you find the toughness of a material.

• Distinguish between direct stress & bending stress.

• What do you mean by Torsional rigidity & lateral rigidity?

• Define “slenderness ratio”. How it is used in a long and short column?

Theory of Machines

• What is Keneddy theorem?

• What is the defect in Davis steering gear?

• Do we need a screw with an efficiency less than 50%?

• What is a backlash?

• What is the damping ratio?

• If $\frac{\omega}{\omega _n} > \sqrt{2}$ whether it will be advisable to provide dampers?

• Define Resonance.

• Define critical speed or whirling speed or whipping speed.

• What is a machine? Giving example, Differentiate between a machine & structure.

• What is the mechanical advantage?

Machine Design

• What are rolling contact bearings?

• What are the antifriction bearings?

• What is the stress coThermodynamicsncentration factor?

• What is the bolt of uniform strength?

• What is the difference in Static Load carrying capacity & Dynamic Load carrying capacity?

• Why we are not using the unit joule for torque instead of N-m.

• What is Low cycle fatigue failure and High cycle fatigue failure? What are the considerations of these while designing a machine?

• What is the mechanical advantage?

• How trains take turns though there is no differential gear?

• Do you know the epicyclical gearbox? What is the practical application of the epicyclical gearbox?

• What is the tooth profile? Which one is better?

Thermodynamics

• What is the availability function for a closed system?

• If it is possible that entropy of a system can decrease during a given process?

• What is a dead state in thermodynamics?

• What is exergy?

• What happens to the triple point line when projected to the P-T plane?

• What is the compressibility factor and what is its value for Vander walls gases.

• What are the initial conditions for the formation of shock waves?

• What do you understand by choking in nozzle flows?

• Is it possible that pressure and velocity decrease simultaneously?

• Distinguish between “Available energy” & Availability?

• What is a pure substance?

• What is a critical point? What is the value f critical temperature, pressure & volume of water?

• What is the sublimation curve, fusion curve & vaporization curve?

• What is Rayleigh Line & Fanno Line?

• What is normal shock & when it occurs?

• What is High-Grade Energy & Low-Grade Energy?

Heat & Mass Transfer

• What is Newton’s Law of cooling?

• What is Recuperator & Regenerators?

• Whether fin can actually reduce heat transfer? is it possible? When?

• What is the difference between Biot no. & Nusselt no?

• Which one is greater, thermal boundary layer or hydrodynamic boundary layer?

• What is film temperature in forced convection flow?

• What is a fully developed region and where it is applicable?

• What is the critical radius of insulation, explain clearly in terms of thermal resistance and heat transfer rate?

•  In what case do you recommend Fin?

• What is the difference between free convection & forced convection in what parameter forced & free convection depend?

Fluid Mechanics and Fluid Machinery

• What is the difference between impulse & reaction turbines?

• Explain unit speed, unit discharge unit power & specific speed.

• Explain NPSH, in which parameter it depends on.

• What is the jet ratio?

• What is the Deriaz turbine?

• Which turbine is good for the tidal power plant?

• What is the Navier-stroke equation?

• What are the significance of Non-Dimensional Numbers (Mach, Weber number)

Internal Combustion Engine

• What is the use of Carburetor in SI Engine, There is a trend towards increases of the injection system in Automobiles, Explain.

• Why Supercharging is not popular with SI Engines?

• What is the performance number?

• Explain Knocking in SI Engine & Mention, the factors that tend to reduce Knocking?

• Explain the difference between Knocking in SI Engine & CI Engine?

• How does “Turbulence” differ from “Swirl”?

• Name some Antiknock additive and explain the mechanism by which they reduce the knock?

Power Plant Engineering

• What is the slip ratio in the thermal power plant?

• In the Pendant superheater whether parallel flow or counter flow heat exchange between steam and flue gases.

• What happens to mass flow in the case of supersaturated flow?

• Why is the clearance provided in the reciprocating compressor?

• Explain turbojet & Rocket Engine.

• What’s the advantage of the compounding of the steam turbines?

• What’s are boiler mounting & accessory.

• Draw the sketch of the pulse jet engine. What are its main advantage & disadvantage?

• Explain the working principle of a scramjet engine, what is an advantage over the ramjet?

• What is the advantage of nuclear power plants over thermal power plants?

• What is the fast breeder reactor?

• What is the circulation ratio and what is its range in power plant?

• One 2-row Curtis turbine is equivalent to how many reaction turbines for the same value of blade velocity and angle of the nozzle?

• What are thermal neutrons?

• What is the breeding ratio?

• What is the application of jet and rocket technology? Which is used in missiles?

Refrigeration and Air-conditioning (RAC)

• What is the utility of a comfort chart?

• What is wet compression?

• To maximize COP what should be the condition of vapour at suction to compression?

• What is the range of NBP (normal boiling point) in the case of most refrigerants?

• Why the COP of CO2 gas is less and still why it is used in transport refrigeration?

• What are the most crucial parts of reciprocating compressors?

• How compressors are selected based on the type of refrigerant?

• What is the correlation between wet-bulb temperatures an adiabatic saturation temperature?

• Why the isothermal compressor is Desirable?

• What is a desirable property of ideal refrigerant?

• Define effective temperature & what is the optimum design condition for comfort for summer A/C?

Production Engineering

• Why arc is slowly extinguished in the case of arc welding?

• Which inert gas is commonly used for a thin workpiece and which inert gas for thick workpiece?

• What is friction welding?

• What is the difference between brazing & braze welding?

• Why hole basis system is adopted in manufacturing?

• What is the 3- 2-1 principle?

• Where diamond pin locator is used?

• How presses are rated?

• What is spring back?

• What is the difference between the fillet and corner radius?

• What are the overhead costs?

• Why depreciation is to be taken into account in industrial management?

• Why the breakeven point is important in any industry?

• What is the sine bar?

• What is the marginal cost and marginal revenue?

• What is shear and where it is provided in case of punching and blanking?

• What is the angle of bite?

• What is the extrusion ratio?

• What is gutter and where it is used?

• Which process is used for making nuclear reactor fuel rods?

• What is the difference between Amorphous and crystalline solids?

• What are the various methods of inspection of casting for internal & external defects?

• Why are allowances provided for in the production of patterns? What do they depend on?

• What is the difference between soldering & brazing?

• What is meant by solid-state welding explain?

• What is cold welding?

• Describe the principle behind resistance welding processes.

• What function should a lubricant perform in the manufacturing process?

• Explain the difference between punching & blanking.

• Explain the difference between discontinuous chips and segment chips.

• Explain the different types of tool wear.

• What is the difference between oblique & orthogonal cutting?

• What is the main difference between jig and fixture?

• What is AOQ?

• What is LTPD?

• What is Producer risk?

• What is Consumer’s risk?

• What is JIT approaches?

• What is group technology? What are its main advantages?

• Define the term “production & productivity.

• What is the significance of ISO 9000 series & 1400 series?

• What is artificial intelligence?

• Which welding process does not require any filler material?

• What is tack weld?

• Which process used for cutting thicker plates?

• Where drooping characteristics of power source is required in arc welding?

Material Science

• What is quazi-crystal?

• What do you understand by free cutting steel? What elements are usually added to make a steel free cutting, & how they make the steel free cutting?

• Explain the various methods of hardening of steel?

• What do you understand by the term “Arrest point” in connecting with the heat treatment of plain carbon steel?

• What influence does grain size have on the mechanical properties of metals?

• Describe the difference between brittle and ductile fracture.

• What is the difference between natural & artificial aging?

Additional Technical Questions

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