70+ Diploma Engineer Trainee - DET Interview Questions and Answers

The 3 main raw materials in the production of iron and steel are iron ore, coal, and limestone.

• Iron ore is the primary raw material used to produce steel.

• Coal is used as a fuel and reducing agent in the production of iron.

• Limestone is used as a flux to remove impurities from the iron ore during the smelting process.

Heat treatment is a process of heating and cooling metals to alter their physical and mechanical properties.

• The three stages of heat treatment are heating, soaking, and cooling.

• Heating is done to a specific temperature depending on the metal and desired outcome.

• Soaking is the holding of the metal at the desired temperature for a specific amount of time.

• Cooling can be done rapidly or slowly depending on the desired outcome.

• Examples of heat treatment processes include annealing...read more

The highest temperature in blast furnace is around 2300°F. It is called bf because it is used to produce pig iron.

• The temperature in blast furnace can reach up to 2300°F

• It is called bf because it is used to produce pig iron

• The process involves heating iron ore, coke, and limestone in a furnace

• The coke burns to produce carbon monoxide, which reacts with the iron ore to produce molten iron

• The limestone reacts with impurities in the iron ore to form slag

Rectifier converts AC to DC. Half wave, full wave and bridge rectifiers are commonly used.

• Rectifier is an electronic device that converts AC to DC.

• Half wave rectifier uses only one diode to convert AC to DC.

• Full wave rectifier uses two diodes to convert AC to DC.

• Bridge rectifier uses four diodes to convert AC to DC.

• Wheatstone bridge rectifier is a modified form of bridge rectifier.

• Circuit diagrams for all three types of rectifiers are available online.

The melting point of iron is 1538°C and its atomic number is 26.

• Iron has a high melting point of 1538°C.

• Its atomic number is 26, which means it has 26 protons in its nucleus.

• Iron is a transition metal and is commonly used in construction and manufacturing.

DRI stands for Direct Reduced Iron, a type of iron produced from the reduction of iron ore.

• DRI is produced by removing oxygen from iron ore without melting it.

• It is used as a substitute for scrap in electric arc furnaces.

• DRI is also used as a feedstock in the production of steel.

• The process of producing DRI is known as the direct reduction process.

• DRI is also known as sponge iron.

Blast furnace is a type of furnace used for smelting to produce industrial metals. BF gas reaction produces carbon monoxide.

• Blast furnace is used for smelting iron ore into pig iron.

• It is a tall cylindrical structure made of steel and lined with refractory bricks.

• The BF gas reaction produces carbon monoxide, which is used as a fuel in various industries.

• The process involves the reduction of iron ore with coke and limestone.

• The molten iron is then drained from the bottom of th...read more

Transistor is a semiconductor device used for amplification and switching of electronic signals.

• Transistor has three layers of semiconductor material - emitter, base, and collector.

• It works by controlling the flow of current between the collector and emitter using the base.

• NPN transistor has a P-type base sandwiched between two N-type layers.

• Symbol of NPN transistor has an arrow pointing outwards from the base.

• Transistors are widely used in electronic devices like amplifiers,...read more

There are several types of iron ore found in India.

• Hematite is the most abundant and widely found iron ore in India.

• Magnetite is another important iron ore found in India.

• Limonite, Siderite, and Iron Pyrites are other types of iron ore found in India.

• India is one of the largest producers of iron ore in the world, with an estimated 2020 production of 206 million metric tons.

Slag is a byproduct of metal smelting process. Coke is used as fuel in blast furnace.

• Slag is a glass-like byproduct of metal smelting process

• It is formed when impurities in the metal ore combine with flux to form a molten mixture

• The mixture is then cooled and solidified to form slag

• Coke, a form of coal, is used as fuel in blast furnace to produce high temperatures needed for smelting

• Coke burns with a high intensity and produces a lot of heat, making it ideal for use in blast ...read more

Steel is an alloy of iron and carbon, with small amounts of other elements.

• Steel is a widely used material in construction, manufacturing, and transportation industries.

• The carbon content in steel can range from 0.2% to 2.1% by weight.

• Other elements such as manganese, chromium, and nickel are often added to improve the properties of steel.

• Different types of steel are produced by varying the composition and processing methods.

• Examples of steel products include beams, pipes, wi...read more

Thermodynamics law is a set of principles that govern the behavior of energy in a system.

• There are four laws of thermodynamics

• The first law states that energy cannot be created or destroyed, only transferred or converted

• The second law states that the total entropy of a closed system will always increase over time

• The third law states that as temperature approaches absolute zero, the entropy of a system approaches a minimum

• The fourth law is a theoretical law that has not yet be...read more

Tempering is a heat treatment process used to improve the toughness and ductility of metals.

• Tempering involves heating a metal to a specific temperature and then cooling it down slowly.

• The purpose of tempering is to reduce the brittleness of the metal and increase its toughness and ductility.

• Tempering is often used after a metal has been hardened to make it more workable.

• Examples of metals that are commonly tempered include steel, aluminum, and copper alloys.

Types of engines include internal combustion, electric, and hybrid. Parts of an engine include cylinders, pistons, and crankshafts.

• Types of engines: internal combustion, electric, hybrid

• Parts of an engine: cylinders, pistons, crankshafts

• Examples of engines: gasoline, diesel, electric motor

• Engine parts work together to convert fuel into energy to power a vehicle or machine

The temperature at which a thermostat valve opens depends on the specific application and type of valve.

• Thermostat valves can open at different temperatures depending on the application.

• The opening temperature can range from below freezing to several hundred degrees Fahrenheit.

• The type of valve, such as a wax pellet or bimetallic strip valve, can also affect the opening temperature.

• For example, a thermostat valve in a car engine may open at around 195°F to regulate coolant fl...read more

A motor is a device that converts electrical energy into mechanical energy, while a signal phase motor operates on single phase power and a three phase motor operates on three phase power.

• Motor is a device that converts electrical energy into mechanical energy

• Single phase motor operates on single phase power

• Three phase motor operates on three phase power

• Three phase motors are more efficient and have higher power output compared to single phase motors

Detonation is an abnormal combustion process in an internal combustion engine where the air-fuel mixture explodes instead of burning smoothly.

• Detonation occurs when the air-fuel mixture in the combustion chamber ignites spontaneously due to high pressure and temperature.

• It results in a rapid and uncontrolled release of energy, causing a sharp increase in pressure and temperature.

• Detonation can lead to engine knocking, increased wear and tear, and reduced engine efficiency.

• It ...read more

There are two main types of engines: internal combustion engines and external combustion engines.

• Internal combustion engines: gasoline engines, diesel engines

• External combustion engines: steam engines, Stirling engines

• Other types: rotary engines, electric engines

CNC stands for Computer Numerical Control.

• CNC is a manufacturing process that uses computerized control systems to operate machine tools.

• It involves the use of pre-programmed software to control the movement of tools and machinery.

• CNC machines are widely used in industries such as automotive, aerospace, and electronics.

• Examples of CNC machines include CNC mills, lathes, routers, and plasma cutters.

The least count of a vernier caliper is the smallest measurement that can be read on the scale.

• The least count is determined by the number of divisions on the main scale and the vernier scale.

• It is calculated by dividing the smallest division on the main scale by the number of divisions on the vernier scale.

• For example, if the smallest division on the main scale is 0.1 mm and the number of divisions on the vernier scale is 10, then the least count would be 0.01 mm.

• The least c...read more

Transistor is a semiconductor device used for amplification and switching. Thermistor is a type of resistor whose resistance varies with temperature. Motor is a machine that converts electrical energy into mechanical energy. Feedback is the process of returning a portion of the output signal back to the input of a system.

• Transistor is used in electronic devices such as radios, televisions, and computers.

• Thermistor is used in temperature sensing applications such as thermostat...read more

IC engine and EV differ in their power source, emissions, and maintenance requirements.

• IC engine runs on fossil fuels, while EV is powered by electricity.

• IC engine emits pollutants like carbon dioxide and nitrogen oxides, while EV produces zero tailpipe emissions.

• IC engine requires regular maintenance like oil changes and tune-ups, while EV has fewer moving parts and requires less maintenance.

• IC engine has limited efficiency due to energy losses in combustion and mechanical s...read more

Questions related to mechanical instruments and components.

• Mechanical instruments: Vernier caliper, micrometer, dial gauge, etc.

• Lathe machine components: Bed, headstock, tailstock, carriage, etc.

• Ferrous metals: Iron, steel, etc. Non-ferrous metals: Copper, aluminum, etc.

• Vernier caliper least count: The smallest measurement that can be read on the scale of a vernier caliper.

Ohm's law states that the current through a conductor between two points is directly proportional to the voltage across the two points.

• Ohm's law is a fundamental law of electrical engineering.

• It states that the current flowing through a conductor is directly proportional to the voltage applied across it.

• The proportionality constant is called resistance and is measured in ohms.

• PCB stands for Printed Circuit Board, which is a board made of insulating material with conductive pa...read more

Electrical maintenance includes preventive, corrective, and predictive maintenance.

• Preventive maintenance involves routine inspections and servicing to prevent breakdowns.

• Corrective maintenance involves repairing or replacing faulty equipment.

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

• Examples of maintenance tasks include cleaning, lubricating, testing, and replacing parts.

• Electrical maintenance also involves ensuring compliance ...read more

Micrometer is a precision measuring instrument used to measure small distances with high accuracy. Its least count is typically 0.01 mm.

• Micrometer is commonly used in engineering and manufacturing industries.

• It consists of a calibrated screw and a measuring scale.

• The least count of a micrometer is the smallest distance that can be measured with it.

• For example, if the least count is 0.01 mm, then the micrometer can measure distances to the nearest 0.01 mm.

• The job location is n...read more

A step transformer is a type of transformer that increases or decreases the voltage level, while a step-down transformer specifically decreases the voltage level.

• A step transformer is used to either step up or step down the voltage level.

• A step-down transformer is specifically designed to decrease the voltage level.

• Step transformers are commonly used in power distribution systems to match the voltage levels between different parts of the system.

• Step-down transformers are used...read more

Micrometer is a precision measuring instrument used to measure small distances with high accuracy.

• Micrometer is also known as a micrometer screw gauge.

• It consists of a calibrated screw and a measuring scale.

• The screw is turned until it touches the object being measured and the reading is taken from the scale.

• Micrometers can measure dimensions as small as 0.001 mm.

• The value of a micrometer depends on its precision and accuracy.

The unit of power in the SI system is the watt (W).

• The watt is defined as one joule per second.

• Power is the rate at which work is done or energy is transferred.

• Other common units of power include kilowatts (kW) and megawatts (MW).

Second law of thermodynamics states that the total entropy of a closed system always increases over time.

• Entropy of a system tends to increase over time

• Heat cannot be completely converted into work

• Efficiency of a heat engine is always less than 100%

• Heat flows from a hotter body to a colder body

• Example: A cup of hot coffee left in a cold room will eventually cool down as heat flows from the hotter coffee to the colder room

2-stroke engines complete a power cycle in one revolution, while 4-stroke engines complete it in two revolutions.

• 2-stroke engines have a simpler design and are lighter than 4-stroke engines.

• 2-stroke engines have a higher power-to-weight ratio than 4-stroke engines.

• 4-stroke engines are more fuel-efficient and have a longer lifespan than 2-stroke engines.

• Examples of 2-stroke engines include chainsaws, dirt bikes, and outboard motors, while examples of 4-stroke engines include c...read more

SMPS, amplifier, and power supply are all electronic devices used to regulate and control electrical power.

• SMPS stands for Switched Mode Power Supply and is used to convert AC to DC power efficiently.

• An amplifier is an electronic device that increases the amplitude of a signal.

• Power supply is a device that supplies electrical energy to one or more electric loads.

• Examples of power supplies include batteries, generators, and solar panels.

Pv and ts diagram of Otto cycle is a graphical representation of the thermodynamic cycle of a four-stroke internal combustion engine.

• Otto cycle is a theoretical cycle that describes the functioning of a spark ignition engine.

• The cycle consists of four processes: intake, compression, power, and exhaust.

• The P-V diagram shows the pressure-volume relationship during each process.

• The T-S diagram shows the temperature-entropy relationship during each process.

• The area enclosed by th...read more

The least count of a vernier caliper and micrometer is the smallest measurement that can be read on the scale.

• The least count of a vernier caliper is typically 0.02 mm or 0.001 inches.

• The least count of a micrometer is typically 0.01 mm or 0.0001 inches.

• The least count is determined by the number of divisions on the scale and the pitch of the screw.

• The smaller the least count, the more precise the measurement can be.

• It is important to use the correct least count when taking m...read more

The policy and company standard refer to the set of rules and regulations that govern the operations and conduct of the company.

• The policy outlines the company's goals, objectives, and procedures for achieving them.

• The company standard refers to the level of quality, safety, and performance that the company expects from its employees and products.

• These policies and standards are designed to ensure compliance with legal and ethical requirements, as well as to promote a positiv...read more

5S is a workplace organization method that aims to improve efficiency and productivity by maintaining cleanliness and orderliness.

• 5S stands for Sort, Set in Order, Shine, Standardize, and Sustain.

• Sort involves removing unnecessary items from the workplace.

• Set in Order involves organizing the remaining items in a logical and efficient manner.

• Shine involves cleaning and maintaining the workplace.

• Standardize involves creating and implementing standard procedures for maintaining ...read more

Instrument names include lathe machine and vernier caliper. Components of lathe machine include bed, headstock, tailstock, and carriage. Least count of vernier caliper varies.

• Lathe machine components: bed, headstock, tailstock, carriage

• Vernier caliper least count varies depending on the instrument

• Other instruments commonly used in engineering include micrometer, dial gauge, and height gauge

Thermodynamics is the branch of physics that deals with the relationships between heat and other forms of energy.

• It studies the behavior of systems in response to changes in temperature, pressure, and volume.

• It is concerned with the conversion of heat energy into other forms of energy and vice versa.

• It has three laws that govern the behavior of thermodynamic systems.

• Examples include the study of engines, refrigeration, and power generation.

• It has applications in various field...read more

There are several types of beams used in construction, including simply supported, cantilever, continuous, and fixed beams.

• Simply supported beams are supported at both ends and have a span between the supports.

• Cantilever beams are supported at only one end and are fixed at the other end.

• Continuous beams have more than two supports and are used for longer spans.

• Fixed beams are supported at both ends and are fixed against rotation at both ends.

• Other types of beams include T-bea...read more

Strain diagram shows the relationship between stress and strain in a material.

• Stress diagram shows the relationship between stress and deformation.

• Strain diagram is used to determine the elastic modulus, yield strength, and ultimate strength of a material.

• Stress diagram is used to determine the stress concentration and stress distribution in a material.

• Both diagrams are important in material testing and analysis.

A generator is a device that converts mechanical energy into electrical energy.

• Generators work on the principle of electromagnetic induction.

• They consist of a rotor and a stator, with the rotor rotating inside the stator.

• The rotation of the rotor creates a magnetic field, which induces an electrical current in the stator windings.

• The electrical current produced by the generator can be used to power electrical devices.

• Examples of generators include hydroelectric generators, wi...read more

Vernier is a measuring scale that provides precise readings. List value is the smallest measurement that can be read on a scale.

• Vernier is used to measure the difference between two readings on a scale

• It is commonly used in engineering and scientific applications

• List value is the smallest measurement that can be read on a scale and is used to determine the precision of the scale

• For example, if the list value of a scale is 0.1 mm, then the smallest measurement that can be read...read more

Mechanical engineering is a branch of engineering that deals with the design, analysis, and manufacturing of mechanical systems.

• Mechanical engineering involves the application of principles of physics and materials science to create and improve mechanical systems.

• It encompasses various sub-disciplines such as thermodynamics, mechanics, robotics, and fluid mechanics.

• Mechanical engineers design and develop machines, tools, engines, and other mechanical devices.

• They work in indu...read more

An engine is a machine that converts energy into mechanical force or motion.

• Engines are used in various applications such as automobiles, aircraft, and power plants.

• They typically work by burning fuel to generate heat, which is then converted into mechanical energy.

• There are different types of engines, including internal combustion engines, steam engines, and electric engines.

• Examples of engines include car engines, jet engines, and steam locomotive engines.

Pump, compressor, and engine are all mechanical devices used to transfer energy.

• A pump is used to move fluids, such as water or oil, from one place to another.

• Types of pumps include centrifugal, positive displacement, and axial flow.

• A compressor is used to increase the pressure of a gas, such as air or natural gas.

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

• An engine is a machine that converts fuel into mechanical energy to power other machines.

• T...read more

Zeroth law of thermodynamics states that if two systems are in thermal equilibrium with a third system, then they are in thermal equilibrium with each other.

• The law establishes the concept of temperature and thermal equilibrium.

• It is the basis for the measurement of temperature.

• It helps in understanding the behavior of heat and energy in different systems.

• For example, if a cup of hot coffee is placed in a room, it will eventually reach the same temperature as the room due to ...read more

Thermodynamic first law states that energy cannot be created or destroyed, only transferred or converted.

• The first law is also known as the law of conservation of energy

• It applies to all forms of energy including mechanical, electrical, and thermal energy

• The law can be expressed mathematically as ΔU = Q - W, where ΔU is the change in internal energy, Q is the heat added to the system, and W is the work done by the system

• The first law is important in understanding energy trans...read more

GD&T stands for Geometric Dimensioning and Tolerancing. It is a system used to define and communicate engineering tolerances.

• GD&T is a symbolic language used to specify the dimensions, form, orientation, and location of features on a part.

• It provides a standardized way to communicate design requirements and ensure the interchangeability of parts.

• GD&T allows engineers to define tolerances more precisely, reducing manufacturing errors and improving product quality.

• It helps in c...read more