600+ Maintenance Engineer Interview Questions and Answers

3 phase power is 440 volts instead of 660 volts due to the configuration of the phases and the relationship between them.

• 3 phase power consists of three separate voltages that are 120 degrees out of phase with each other

• The line-to-line voltage in a 3 phase system is √3 times the phase voltage

• In a 3 phase system, the line-to-line voltage is 440 volts (220 volts * √3)

SMPS is a power supply that uses high-frequency switching to convert AC voltage to DC voltage.

• SMPS is more efficient than traditional linear power supplies

• It uses a switching regulator to control the output voltage

• SMPS can be found in computers, TVs, and other electronic devices

• It can be designed to work with different input voltages and frequencies

Defects in casting process include porosity, shrinkage, cold shuts, misruns, and inclusions.

• Porosity: air or gas trapped in the casting

• Shrinkage: volume reduction during solidification

• Cold shuts: incomplete fusion of molten metal

• Misruns: incomplete filling of the mold cavity

• Inclusions: foreign materials trapped in the casting

Different types of bearings include ball bearings, roller bearings, plain bearings, and fluid bearings.

• Ball bearings are used in applications requiring low friction and high speed, such as in wheels and conveyor belts.

• Roller bearings are suitable for heavy radial loads, such as in automotive transmissions and industrial machinery.

• Plain bearings, also known as bushings, are used in applications where lubrication is difficult, such as in hinges and pivots.

• Fluid bearings use a t...read more

Pneumatic systems use compressed air to transmit power, while hydraulic systems use fluid (usually oil) to transmit power.

• Pneumatic systems use air as the working fluid, while hydraulic systems use oil or other fluids.

• Pneumatic systems are generally cleaner and easier to maintain than hydraulic systems.

• Hydraulic systems can handle higher loads and pressures compared to pneumatic systems.

• Pneumatic systems are often used in applications where cleanliness is important, such as i...read more

In my previous job, I was responsible for electrical maintenance of motor transformers and other machines.

• Performed regular maintenance and troubleshooting of motor transformers.

• Inspected and repaired electrical components and circuits.

• Conducted preventive maintenance to ensure optimal performance and minimize downtime.

• Collaborated with a team to diagnose and resolve electrical issues.

• Maintained accurate records of maintenance activities and equipment status.

• Implemented safet...read more

Diagnosing a fault in an AGV motor involves checking for physical damage, testing electrical connections, and analyzing error codes.

• Inspect the motor for physical damage such as broken wires or burnt components

• Check the electrical connections for loose wires or faulty connections

• Use a multimeter to test the voltage and continuity of the motor

• Analyze any error codes or warning lights on the AGV system for clues to the fault

• Consult the manufacturer's manual for troubleshooting ...read more

Check power source, power switch, fuse, and connections.

• Check if the power source is working and supplying electricity to the machine.

• Ensure the power switch is turned on.

• Inspect the fuse to see if it is blown and needs replacement.

• Check all connections and cables to ensure they are properly connected and not damaged.

• Test the machine with a different power source to rule out electrical issues.

Relative humidity in OT is maintained through proper ventilation, air conditioning, and dehumidification.

• Proper ventilation helps to circulate air and prevent moisture buildup.

• Air conditioning helps to cool and dehumidify the air.

• Dehumidifiers can be used to remove excess moisture from the air.

• Regular maintenance of HVAC systems is important to ensure proper functioning.

• Monitoring and controlling humidity levels is crucial for preventing the growth of bacteria and fungi.

• Relat...read more

Blow down in boilers is necessary to remove impurities and maintain water quality. The pH of water in the boiler should be monitored and adjusted using chemicals like sodium hydroxide or sulfuric acid.

• Blow down is done to remove impurities such as dissolved solids, suspended solids, and alkalinity from the boiler water.

• The pH of water in the boiler should be maintained within a specific range to prevent corrosion and scale formation.

• Chemicals like sodium hydroxide (NaOH) or s...read more

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

A strain gauge is a device used to measure strain or deformation in an object.

• It consists of a thin wire or foil that is attached to the object being measured.

• As the object deforms, the wire or foil also deforms, causing a change in its electrical resistance.

• This change in resistance is measured and used to calculate the amount of strain or deformation in the object.

• Strain gauges are commonly used in engineering and manufacturing to monitor the structural integrity of buildin...read more

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

There are 5 flags in 8085 microprocessor - Carry, Auxiliary Carry, Sign, Zero, and Parity.

• 8085 microprocessor has 5 flags

• Carry flag is set when there is a carry out of the MSB in an arithmetic operation

• Auxiliary Carry flag is set when there is a carry out of bit 3 in an arithmetic operation

• Sign flag is set when the result of an operation is negative

• Zero flag is set when the result of an operation is zero

• Parity flag is set when the result of an operation has even number of 1s ...read more

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

To connect the CCTV network from SCR to TER, you need to establish a physical connection between the two locations and configure the network settings accordingly.

• Ensure there is a direct physical connection (such as Ethernet cable) between the SCR and TER locations.

• Configure the network settings on both ends to ensure they are on the same network and can communicate with each other.

• Test the connection to ensure the CCTV network is successfully connected from SCR to TER.

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

1kcal is the amount of energy required to raise the temperature of 1 kilogram of water by 1 degree Celsius.

• 1kcal is a unit of energy measurement.

• It is commonly used to measure the energy content of food.

• 1kcal is equal to 1000 calories.

• Calories are a measure of the amount of energy in food.

• The energy content of food is usually measured in kilocalories (kcal) or kilojoules (kJ).

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

To troubleshoot a recurring problem in equipment, I would follow a systematic approach to identify the root cause and implement a permanent solution.

• Start by gathering information about the problem, including when it occurs and any patterns or common factors.

• Inspect the equipment thoroughly to identify any visible signs of damage or wear.

• Review maintenance records and previous repair attempts to see if there is a recurring issue that has not been fully resolved.

• Use diagnostic...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

Oil can float on water despite having a higher density due to differences in molecular structure and polarity.

• Oil molecules are non-polar and do not form strong interactions with water molecules

• Water molecules are polar and form hydrogen bonds, causing them to stick together and create a denser structure

• The difference in polarity and molecular structure allows oil to float on water

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

Ohm's Law states that the current flowing through a conductor is directly proportional to the voltage applied across it, given a constant resistance.

• Ohm's Law: V = I * R (Voltage = Current * Resistance)

• Current is directly proportional to Voltage when Resistance is constant

• Higher voltage leads to higher current flow, and vice versa

• Lower resistance leads to higher current flow, and vice versa

• Example: If a circuit has a voltage of 12V and a resistance of 4 ohms, the current flow...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 process for identifying a step sensor error involves checking for physical damage, calibrating the sensor, and testing its functionality.

• Inspect the step sensor for any physical damage or wear and tear.

• Calibrate the sensor according to manufacturer's instructions.

• Test the sensor by taking a known number of steps and comparing the reading to the actual count.

• Check the wiring and connections for any issues that may be causing the error.

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