100+ Junior Mechanical Engineer Interview Questions and Answers

Overview of Tunnel Boring Machines, their maintenance, and safety measures in engineering projects.

• TBMs use a rotating cutter head to excavate soil and rock, transporting material via a conveyor system.

• Common hydraulic failures include leaks in hoses, pump malfunctions, and pressure loss due to blockages.

• Preventive maintenance involves regular inspections, lubrication, and replacing worn parts to avoid breakdowns.

• Thrust force is the force applied to push the TBM forward, whil...read more

Types of gearboxes include spur, helical, bevel, worm, and planetary. The most commonly used gearbox in our plant is the helical gearbox.

• Types of gearboxes: spur, helical, bevel, worm, planetary

• Helical gearbox is commonly used for its efficiency and smooth operation

• Spur gearbox is simple and cost-effective

• Bevel gearbox is used for right angle drives

• Worm gearbox provides high torque but lower efficiency

To improve cycle time, focus on process optimization and efficiency. Rejection control involves identifying root causes of defects and implementing corrective actions.

• Implement lean manufacturing principles to streamline processes and reduce waste

• Utilize automation and technology to speed up production

• Regularly analyze data and performance metrics to identify bottlenecks and areas for improvement

• Train employees on best practices and quality standards to reduce errors and defe...read more

Air mainly contains water vapor due to the evaporation of water bodies, plants, and human activities.

• Water vapor is the most abundant gas in the atmosphere due to evaporation from oceans, lakes, rivers, and plants.

• Other vapors like alcohol, gasoline, or perfume are present in the air but in much lower concentrations compared to water vapor.

• Water vapor is constantly being added to the air through processes like transpiration from plants and evaporation from human activities li...read more

304, 304L, and 316 stainless steel grades differ in their carbon content, corrosion resistance, and applications.

• 304 stainless steel contains 18% chromium and 8% nickel, while 304L has a lower carbon content to prevent sensitization during welding.

• 316 stainless steel contains 16-18% chromium, 10-14% nickel, and 2-3% molybdenum for increased corrosion resistance, making it suitable for marine environments.

• 304 and 304L are commonly used in food processing equipment, kitchen app...read more

The formula for calculating stress and strain in materials is based on Hooke's Law.

• Stress (σ) = Force (F) / Area (A)

• Strain (ε) = Change in length (ΔL) / Original length (L)

• Hooke's Law: Stress = Young's Modulus x Strain

• Example: If a force of 100 N is applied to a material with a cross-sectional area of 2 m^2, the stress would be 50 N/m^2

The atmosphere gradually thins out as altitude increases, eventually merging into outer space.

• The atmosphere is composed of several layers, with the exosphere being the outermost layer before transitioning into space.

• The Kármán line, located at an altitude of 100 km (62 miles) above sea level, is often considered the boundary between Earth's atmosphere and outer space.

• Beyond the Kármán line, the atmosphere becomes extremely thin and eventually merges into the vacuum of space.

Gases in the atmosphere do not separate out according to mass due to the constant mixing caused by wind and turbulence.

• Constant mixing caused by wind and turbulence prevents gases from separating based on mass

• Gravity also plays a role in keeping gases well-mixed in the atmosphere

• Different gases have different molecular weights but are still evenly distributed in the atmosphere

Effective lubrication and maintenance strategies can significantly reduce mechanical breakdowns in machinery.

• Use the correct type of grease for specific applications, e.g., lithium grease for high-temperature environments.

• Select appropriate bolts with proper torque specifications to prevent loosening and failure.

• Implement regular gear lubrication schedules to ensure smooth operation and reduce wear.

• Monitor operating conditions and perform predictive maintenance to identify po...read more

Conventional power plants use fossil fuels to generate electricity while non-conventional power plants use renewable sources.

• Conventional power plants burn fossil fuels like coal, oil, and natural gas to generate electricity

• Non-conventional power plants use renewable sources like solar, wind, hydro, and geothermal energy

• Conventional power plants are cheaper to build and operate but contribute to pollution and climate change

• Non-conventional power plants are more expensive to b...read more

Industrial hydraulic system consists of various components like relief valve, pressure reducing valve, and directional control valves (DCVs) to control the flow and pressure of hydraulic fluid.

• Industrial hydraulic system uses hydraulic fluid to transmit power.

• Relief valve is used to limit the maximum pressure in the system to prevent damage.

• Pressure reducing valve is used to maintain a constant pressure in a branch of the system.

• Directional control valves (DCVs) control the f...read more

The number of temp. required to melt mild steel depends on the specific grade of steel. Syco cranes are used for heavy lifting. Different types of gears can be used based on the application. Various types of pumps can be used depending on the requirements. Head refers to the pressure generated by a pump. Alignment is crucial for proper functioning of mechanical systems.

• Number of temp. required to melt mild steel depends on the grade of steel

• Syco cranes are used for heavy lift...read more

There are mainly three types of bearings nomenclature: ball bearings, roller bearings, and plain bearings.

• Ball bearings

• Roller bearings

• Plain bearings

Yes, I have done pre-maintenance of equipment and tracked maintenance status.

• I have conducted regular inspections of equipment to identify potential issues before they become major problems.

• I have kept detailed records of maintenance activities, including dates, tasks performed, and any issues encountered.

• I have worked with maintenance teams to develop and implement preventative maintenance plans.

• I have used software tools to track maintenance schedules and generate reports o...read more

The fabrication of a structure requires detailed fabrication drawings.

• Fabrication drawings provide detailed information on the dimensions, materials, and assembly of the structure.

• These drawings are typically created by a structural engineer or draftsman.

• They may include plans, elevations, sections, and details of the structure.

• Fabrication drawings are essential for ensuring that the structure is built to the correct specifications and meets safety standards.

• Examples of struc...read more

Thermal power plant generates electricity by converting heat energy into electrical energy.

• Fuel is burned to produce heat

• Heat is used to produce steam

• Steam drives the turbine

• Turbine drives the generator

• Generator produces electricity

• Examples: coal-fired power plant, gas-fired power plant, nuclear power plant

The type of reducer used in pipe rack depends on the specific application and requirements.

• Reducers are used to connect pipes of different sizes in a pipe rack.

• The type of reducer used depends on the size and material of the pipes being connected.

• Common types of reducers include concentric, eccentric, and swage reducers.

• Concentric reducers have a symmetrical shape and are used when pipes of different sizes need to be connected in a straight line.

• Eccentric reducers have an off...read more

Priming is the process of removing air from the pump and filling it with liquid. Head of pump is the height to which the pump can raise water.

• Priming is done to remove air from the pump and fill it with liquid to ensure proper functioning.

• Head of pump is the maximum height to which the pump can raise water.

• Priming is necessary for self-priming pumps, while non-self-priming pumps require manual priming.

• Head of pump is affected by factors such as pump speed, impeller diameter, ...read more

Oil consumption of an engine per hour can be calculated by measuring the difference in oil level before and after a certain period of time.

• Calculate the initial oil level in the engine.

• Run the engine for a specific number of hours.

• Measure the final oil level in the engine.

• Subtract the final oil level from the initial oil level to determine the amount of oil consumed per hour.

• Divide the amount of oil consumed by the number of hours the engine ran to get the oil consumption per...read more

P&ID shows process flow and instrumentation, while isometric drawings depict 3D representations of piping systems.

• P&ID (Piping and Instrumentation Diagram) illustrates the relationship between piping, equipment, and instrumentation.

• Isometric drawings provide a 3D view of piping layouts, showing how pipes are arranged in space.

• P&ID includes symbols for valves, pumps, and instruments, while isometric drawings focus on the physical layout.

• Example: A P&ID might show a pump connec...read more

Clouds move due to the combination of wind, temperature, and pressure differences in the atmosphere.

• Clouds are carried along by the wind in the atmosphere.

• Temperature differences cause air to rise or sink, affecting cloud movement.

• Pressure variations also play a role in cloud motion.

• For example, warm air rising from the ground can create cumulus clouds that move with the wind.

Engineering materials include metals, polymers, ceramics, and composites. Stress-strain refers to the relationship between applied force and deformation.

• Engineering materials include metals, polymers, ceramics, and composites

• Metals have high strength and ductility, such as steel and aluminum

• Polymers are lightweight and flexible, like plastics and rubber

• Ceramics are hard and brittle, such as glass and ceramics

• Composites are combinations of different materials, like carbon fibe...read more

The process for selecting a pump involves determining the required flow rate, head, type of fluid, system characteristics, and budget constraints.

• Identify the required flow rate and head for the system

• Consider the type of fluid being pumped (e.g. water, oil, chemicals)

• Evaluate the system characteristics such as pressure, temperature, and viscosity

• Take into account budget constraints and operational costs

• Select a pump type that meets the requirements identified

Process piping refers to the system of pipes used to transport fluids in industrial settings.

• Process piping is used in various industries such as oil and gas, chemical, pharmaceutical, and food processing.

• It is designed to safely transport liquids, gases, and solids from one point to another within a facility.

• Process piping systems include pipes, fittings, valves, and other components to control the flow of materials.

• Proper design and installation of process piping is crucial...read more

Isometric drawings are required for fabrication of pipelines.

• Isometric drawings show the 3D view of the pipeline and its components.

• They include information about the size, shape, and orientation of the pipes.

• Isometric drawings also show the location of valves, fittings, and other components.

• These drawings are used by fabricators to create the pipeline according to the design.

• Other types of drawings that may be required include P&IDs and equipment layout drawings.

Sheet metal processing methods include cutting, bending, forming, and joining techniques.

• Cutting: Shearing, laser cutting, water jet cutting

• Bending: Press brake bending, roll bending

• Forming: Stamping, deep drawing, spinning

• Joining: Welding, riveting, adhesive bonding

Thermal power plants use fossil fuels to generate electricity. They have advantages and disadvantages.

• Advantages: Reliable source of electricity, low operating cost, high efficiency, easy to operate and maintain

• Disadvantages: High initial cost, environmental pollution, non-renewable source of energy, limited availability of fuel

• Example: Advantages - Thermal power plants provide a reliable source of electricity that can be generated 24/7. They have low operating costs and high...read more