500+ Maintenance Engineer Interview Questions and Answers

Colour coding on three phase supply RYB is used for easy identification and proper connection of phases.

• Colour coding helps in identifying different phases easily

• Prevents incorrect connections which can lead to equipment damage or accidents

• Standardizes the wiring system for consistency and safety

• Red phase (R), Yellow phase (Y), Blue phase (B) are commonly used for RYB colour coding

Temperature rise of hydraulic oil in die casting machine is caused by friction, overloading, inadequate cooling, or contaminated oil.

• Friction between moving parts can generate heat and increase oil temperature

• Overloading the machine can cause excessive heat generation

• Inadequate cooling system or malfunctioning cooling components can lead to temperature rise

• Contaminated oil with debris or moisture can reduce lubrication efficiency and increase friction

Up milling and down milling are two types of milling operations used in machining.

• Up milling is also known as conventional milling, where the cutter rotates against the direction of feed.

• Down milling is also known as climb milling, where the cutter rotates in the same direction as the feed.

• Up milling produces a rougher surface finish and generates more heat, while down milling produces a smoother surface finish and generates less heat.

• Up milling is preferred for tough materia...read more

Boilers are classified based on their design, fuel type, and application.

• Fire-tube boilers

• Water-tube boilers

• Electric boilers

• Gas boilers

• Oil boilers

• Solid fuel boilers

• Combination boilers

• Condensing boilers

• Industrial boilers

• Residential boilers

Water chiller maintenance involves regular cleaning, inspection, and servicing to ensure optimal performance and prevent breakdowns.

• Regularly clean the condenser and evaporator coils to remove dirt and debris

• Check refrigerant levels and top up if necessary

• Inspect and replace filters as needed

• Check for leaks and repair any damaged components

• Schedule routine maintenance with a qualified technician

• Keep a maintenance log to track service history and identify trends

I will prioritize maintenance tasks based on their urgency and impact on production.

• Create a maintenance schedule that does not interfere with production schedules

• Identify critical equipment and prioritize their maintenance

• Ensure that maintenance tasks are completed within the allotted time

• Communicate with production team to coordinate maintenance activities

• Implement preventive maintenance to reduce downtime

• Train production team to perform basic maintenance tasks

• Use technolog...read more

Mounting and demounting methods of a bearing involve using various tools and techniques to properly install and remove the bearing from its housing.

• Mounting methods include press fitting, heating, and using specialized tools like bearing pullers

• Demounting methods involve using bearing pullers, hydraulic presses, or heating to expand the housing

• Proper alignment and lubrication are crucial for successful mounting and demounting

• Examples of mounting tools include bearing heaters,...read more

LMTD stands for Logarithmic Mean Temperature Difference and is used to calculate the temperature difference in a heat exchanger.

• LMTD is a method used to determine the temperature difference between two fluids in a heat exchanger

• It takes into account the temperature difference at different points along the length of the heat exchanger

• LMTD is used to calculate the heat transfer rate in a heat exchanger

• It is calculated using the formula LMTD = (ΔT1 - ΔT2) / ln(ΔT1 / ΔT2)

• LMTD is ...read more

SMPS stands for Switched Mode Power Supply. It is an electronic power supply that efficiently converts electrical power.

• SMPS is a type of power supply that uses switching regulators to convert electrical power.

• It is commonly used in electronic devices such as computers, televisions, and mobile phones.

• SMPS operates by rapidly switching the input voltage on and off to regulate the output voltage.

• It provides a more efficient and compact solution compared to traditional linear po...read more

There are various types of motors, welding methods, heating techniques, and power factors in engineering.

• Types of motors include AC motors (induction, synchronous), DC motors (brushed, brushless), stepper motors, etc.

• Types of welding include arc welding, MIG welding, TIG welding, spot welding, etc.

• Types of heating methods include conduction, convection, radiation, induction heating, etc.

• Power factor types include leading power factor, lagging power factor, unity power factor,...read more

QAMS is Quality Assurance Management System, which is a digital system for submitting Corrective Actions instead of manual hard copy submissions.

• QAMS is a digital system used for submitting Corrective Actions electronically.

• It streamlines the process of submitting and tracking Corrective Actions compared to manual hard copy submissions.

• QAMS allows for easier collaboration and communication among team members involved in the corrective action process.

• It provides a centralized ...read more

The number of points in a PM checklist varies depending on the equipment being checked.

• PM checklists are specific to each piece of equipment.

• The number of points in a PM checklist can range from a few to hundreds.

• Points in a PM checklist can include tasks such as inspecting, cleaning, and lubricating equipment.

• The purpose of a PM checklist is to ensure that equipment is properly maintained and to prevent breakdowns.

• The number of points in a PM checklist can be adjusted based ...read more

To check ball screw backlash, turret alignment, spindle run out, and ATC alignment, follow these steps:

• For ball screw backlash, use a dial indicator to measure the amount of play in the screw

• For turret alignment, use a test bar to check the alignment of the turret with the spindle axis

• For spindle run out, use a dial indicator to measure the amount of deviation in the spindle rotation

• For ATC alignment, use a test bar to check the alignment of the tool changer with the spindle ...read more

This question covers properties of air, generation of CO2 gas, and its applications.

• Air is a mixture of gases, primarily nitrogen and oxygen

• CO2 gas is generated through combustion of fossil fuels, fermentation, and respiration

• CO2 gas is used in fire extinguishers, carbonation of beverages, and as a refrigerant

Current can be measured using an ammeter, which measures the flow of electric charge in a circuit.

• Use an ammeter to measure current

• Connect the ammeter in series with the circuit

• Ensure the ammeter is set to the appropriate range for the expected current

• Read the current value displayed on the ammeter

• Example: To measure the current flowing through a light bulb, connect the ammeter in series with the bulb and read the displayed value

I have worked on machines with various geometries, including cylindrical, rectangular, and spherical shapes.

• Worked on machines with cylindrical geometry, such as lathes and milling machines.

• Handled machines with rectangular geometry, like conveyor belts and packaging equipment.

• Dealt with machines with spherical geometry, such as ball bearings and rotary valves.

A CNC machine can have 3, 4, or 5 axes depending on its configuration.

• The X, Y, and Z axes are common in 3-axis machines.

• 4-axis machines add a rotary axis, usually the A-axis.

• 5-axis machines add a second rotary axis, usually the B-axis.

• Some machines may have additional axes for specialized operations, such as milling machines with a tilting spindle head.

• The number of axes determines the machine's capabilities and the complexity of its programming.

Tools can fall due to various reasons such as improper storage, lack of maintenance, human error, and environmental factors.

• Improper storage or handling of tools

• Lack of maintenance or inspection of tools

• Human error such as dropping or mishandling the tool

• Environmental factors such as vibrations or unstable surfaces

• Inadequate training or experience of the user

An injection molding machine is a manufacturing tool used to produce plastic parts by injecting molten material into a mold.

• It consists of a hopper, an injection unit, a clamping unit, and a control unit.

• The hopper is used to store the plastic material that will be melted and injected into the mold.

• The injection unit melts the plastic and injects it into the mold.

• The clamping unit holds the mold in place during the injection process.

• The control unit manages the entire process...read more

Yes, I have knowledge of conveyor belts, grinding mills, kilns, and feed mixers.

• I have experience in maintaining and repairing conveyor belts, including belt splicing and replacement.

• I am familiar with the operation and maintenance of grinding mills, including lubrication and alignment.

• I have worked with kilns, including troubleshooting and repairing issues with burners and refractory materials.

• I have experience maintaining and repairing feed mixers, including augers and moto...read more

Yes, I have experience in programming and operating as well as maintenance department.

• I have experience in programming languages such as Java and Python.

• I have operated and maintained various types of machinery and equipment.

• I have also developed and implemented maintenance schedules and procedures.

• For example, I have programmed and operated a CNC machine and maintained it regularly to ensure optimal performance.

• I have also developed a maintenance schedule for a production li...read more

The interview question covers Hartman working principle, types of maintenance, EOT cranes working, oil types, work planning, and execution.

• Hartman working principle involves the use of a magnetic field to detect metal objects in a conveyor belt.

• Types of maintenance include corrective, preventive, predictive, and condition-based maintenance.

• EOT cranes work by using a trolley and hoist to move heavy loads horizontally and vertically.

• Oil types used in maintenance include hydraul...read more

Balancing in paint mixing is achieved by adjusting the proportions of different colors. Temperature is maintained using heating or cooling systems.

• Balancing in paint mixing is achieved by adjusting the proportions of different colors to create the desired shade.

• Temperature maintenance can be done using heating or cooling systems to keep the paint at the optimal temperature for application.

• Regular monitoring of the temperature and viscosity of the paint is essential to ensure ...read more

The size of wire is decided based on the current carrying capacity and the distance it needs to travel.

• Calculate the maximum current that will flow through the wire

• Determine the distance the wire needs to travel

• Refer to a wire gauge chart to find the appropriate wire size

• Consider the type of insulation needed for the wire

• Example: For a 20A current and a distance of 50ft, a 12-gauge wire with appropriate insulation would be needed

PTED process involves the use of chemicals to remove contaminants from wastewater.

• PTED stands for Physical-Chemical Treatment with Electrochemical Disinfection.

• The process involves the use of chemicals such as chlorine, ozone, or hydrogen peroxide to remove contaminants from wastewater.

• Electrochemical disinfection is used to kill bacteria and other pathogens in the treated water.

• The chemicals used in PTED process help in breaking down organic matter and neutralizing harmful s...read more

Threads are helical ridges or grooves on the surface of a cylindrical object. There are different types of threads.

• Unified Thread Standard (UTS)

• Metric Thread Standard

• Pipe Thread Standard

• ACME Thread

• Buttress Thread

• Knuckle Thread

• Square Thread

• Round Thread

Valves are devices used to control the flow of fluids or gases. There are several types of valves used in different applications.

• Gate valve

• Ball valve

• Butterfly valve

• Globe valve

• Check valve

• Diaphragm valve

• Needle valve

• Pressure relief valve

• Safety valve

The plan of action would involve identifying the issue, assessing its severity, determining the root cause, and implementing a solution.

• Identify the issue through observation and analysis

• Assess the severity of the issue to determine the urgency of the solution

• Determine the root cause of the issue to prevent it from recurring

• Implement a solution that addresses the root cause and resolves the issue

• Monitor the solution to ensure its effectiveness and make adjustments as necessar...read more

There are generally 4 types of maintenance: corrective, preventive, predictive, and condition-based.

• Corrective maintenance involves fixing a problem after it has occurred.

• Preventive maintenance involves scheduled maintenance to prevent problems from occurring.

• Predictive maintenance involves using data and analytics to predict when maintenance is needed.

• Condition-based maintenance involves monitoring equipment and performing maintenance when certain conditions are met.

• Examples...read more

My current CTC is $60,000 and I am looking for a 10% increment.

• My current CTC is $60,000

• I am seeking a 10% increment

• This would bring my desired CTC to $66,000

Utility operation and mechanical maintenance are crucial for efficient machine shop operations.

• Utility operation involves managing power, water, and air supply to the machines.

• Mechanical maintenance includes regular inspections, cleaning, and repairs of the machines.

• Proper lubrication and alignment of machine parts are also important for smooth operations.

• Examples of machines in a machine shop include lathes, milling machines, and grinders.

Pascal's law states that pressure applied to a fluid in a closed container is transmitted equally in all directions.

• Pascal's law is used in hydraulic systems to transmit force and motion.

• It is also used in braking systems of vehicles.

• The law is applicable in medical devices like blood pressure monitors and ventilators.

• Pascal's principle is used in the operation of hydraulic presses and lifts.

• The law is named after Blaise Pascal, a French mathematician and physicist.

MIG welding uses a continuously feeding wire electrode, while TIG welding uses a tungsten electrode to produce the weld.

• MIG welding is faster and easier to learn than TIG welding

• TIG welding produces higher quality and more precise welds than MIG welding

• MIG welding is better for thicker materials, while TIG welding is better for thinner materials

• MIG welding produces more spatter and requires more cleanup than TIG welding

• TIG welding is more expensive due to the need for a separ...read more

A valve is a device that regulates, directs or controls the flow of a fluid by opening, closing, or partially obstructing various passageways.

• Valves are used in various industries such as oil and gas, water treatment, chemical processing, and power generation.

• They can be used to control the flow of liquids, gases, and even slurries.

• Valves can be manual or automated, and can be operated by hand, electric motors, or pneumatic actuators.

• Examples of valves include ball valves, ga...read more

Pascal's law states that pressure applied to a fluid in a closed container is transmitted equally in all directions.

• Pressure applied to a fluid in a closed container is transmitted equally in all directions

• The pressure applied to a fluid is directly proportional to the force applied

• This law is used in hydraulic systems to transmit force and pressure

• Examples include car brakes and hydraulic lifts

Panel preventive maintenance is the regular inspection and servicing of electrical panels to ensure their proper functioning.

• It involves checking for loose connections, damaged components, and signs of wear and tear.

• Cleaning the panels and removing any debris or dust that may have accumulated.

• Testing the panels to ensure they are functioning properly and addressing any issues that are found.

• Examples include checking the circuit breakers, fuses, and wiring in the panel.

• Regular...read more

Hydraulic system is a technology that uses liquid to transmit power and circuits are the pathways through which the liquid flows.

• Hydraulic systems use a liquid, usually oil, to transmit power.

• The liquid is pressurized and flows through a series of tubes and hoses.

• Circuits are the pathways through which the liquid flows.

• There are two types of circuits: open and closed.

• Open circuits allow the fluid to flow back to the reservoir, while closed circuits keep the fluid in a continu...read more

I tend to be too detail-oriented, which can sometimes slow down my work.

• I have a tendency to focus on small details and may need to remind myself to step back and look at the bigger picture

• I am working on improving my time management skills to ensure that I am able to complete tasks efficiently

• I am open to constructive feedback and am always looking for ways to improve my weaknesses

Preventive maintenance is the most necessary type of maintenance.

• Prevents breakdowns and extends equipment lifespan

• Reduces repair costs and downtime

• Increases safety and reliability

• Examples: regular inspections, lubrication, cleaning, calibration

Condensers are used in power plants to convert steam back into water for reuse in the boiler.

• Condensers increase the efficiency of the power plant by allowing the reuse of water.

• They reduce the amount of water needed for the power plant.

• Condensers also help to maintain a vacuum in the turbine exhaust, which increases the power output.

• Examples of condensers used in power plants include surface condensers and jet condensers.

The earthing conductor in a 3 pin socket is big in size to provide a low resistance path for fault currents to safely dissipate into the ground.

• Large size reduces resistance, allowing fault currents to flow easily

• Ensures safety by preventing electric shocks

• Meets regulatory standards for grounding systems

• Protects against electrical fires and equipment damage

The previous company used natural gas as the boiler fuel. The market price of fuel/kg varies depending on location and supplier.

• Previous company used natural gas as boiler fuel

• Market price of fuel/kg varies based on location and supplier

• Provide specific examples if possible

Compressors are mechanical devices that increase the pressure of a gas by reducing its volume.

• Types of compressors include reciprocating, rotary screw, centrifugal, and scroll compressors.

• Reciprocating compressors use pistons to compress gas, commonly used in household refrigerators.

• Rotary screw compressors use two rotating screws to compress gas, often used in industrial applications.

• Centrifugal compressors use a rotating impeller to create centrifugal force and compress gas...read more

Yes, I am willing to work in desert temperatures of 55'C as a Maintenance Engineer.

• I am familiar with the challenges of working in extreme temperatures and have experience working in similar conditions.

• I am aware of the safety precautions that need to be taken in such conditions.

• I am comfortable working with equipment that is designed to withstand high temperatures.

• I am willing to adapt my work schedule to ensure that I am working during the cooler parts of the day.

• I am commi...read more

A battery converts chemical energy into electrical energy. For example, a lead-acid battery used in cars.

• Batteries work by converting chemical energy into electrical energy

• Common types of batteries include lead-acid, alkaline, lithium-ion, and nickel-cadmium

• Lead-acid batteries are commonly used in cars and work by converting lead and lead oxide into lead sulfate

• Alkaline batteries use zinc and manganese dioxide to create a chemical reaction

• Lithium-ion batteries are commonly us...read more

The procedure for spindle dismandle involves several steps to ensure safety and proper disassembly.

• Disconnect power supply and lockout/tagout equipment

• Remove any attachments or accessories from the spindle

• Remove the spindle from the machine using appropriate tools

• Disassemble the spindle by removing the retaining nut, bearings, and other components

• Inspect all components for wear or damage and replace as necessary

• Clean all components thoroughly before reassembly

• Reassemble the s...read more

Pressure parts in boiler shutdown are inspected and maintained to ensure safe and efficient operation.

• Pressure parts include boiler tubes, headers, and drums.

• During shutdown, pressure parts are inspected for signs of wear, corrosion, and damage.

• Maintenance tasks may include cleaning, repairing, or replacing pressure parts as needed.

• Proper maintenance of pressure parts is crucial for preventing accidents and ensuring efficient boiler operation.