MACHINE DESIGN INTERVIEW QUESTIONS AND ANSWERS

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MACHINE DESIGN INTERVIEW QUESTIONS AND ANSWERS

What is machine design?

Machine design is the process of designing and creating machines, tools, and mechanical systems to perform specific tasks or functions. It involves understanding the principles of mechanics, materials science, and manufacturing processes to develop a product that meets performance, safety, and reliability requirements.

What are the steps involved in the machine design process?

The steps involved in the machine design process include conceptualization, analysis, synthesis, detailing, and manufacturing. The conceptualization stage involves defining the problem, identifying the requirements, and developing a design concept. The analysis stage involves analyzing the design for strength, stiffness, and stability. The synthesis stage involves selecting the components and creating the detailed design. The detailing stage involves creating drawings, specifications, and manufacturing instructions. The manufacturing stage involves producing the product.

What are the different types of loads that a machine can experience?

A machine can experience different types of loads, including static loads, dynamic loads, impact loads, thermal loads, and fatigue loads. Static loads are steady loads that do not change over time. Dynamic loads are loads that change over time and can cause vibrations. Impact loads are sudden and intense loads that can cause damage to the machine. Thermal loads are caused by changes in temperature and can cause thermal expansion or contraction. Fatigue loads are caused by cyclic loading and can result in fatigue failure.

How do you select materials for machine design?

Materials for machine design should be selected based on their mechanical properties, including strength, stiffness, toughness, and fatigue resistance. Other factors to consider include corrosion resistance, wear resistance, and cost. The material should also be compatible with the manufacturing process and any environmental factors that the machine will be exposed to.

What is a safety factor in machine design?

A safety factor is a factor of safety that is used in machine design to ensure that the machine can withstand loads that are higher than the expected operating loads. It is a ratio of the ultimate strength of the material to the maximum stress that the material is expected to experience. A safety factor of 2 means that the machine is designed to withstand twice the expected load.

What is the difference between stress and strain?

Stress is the force per unit area that is applied to a material, while strain is the deformation or change in shape that occurs in response to stress. Stress is a measure of the internal forces that are acting on the material, while strain is a measure of the material’s response to those forces.

How do you calculate the bending stress in a beam?

The bending stress in a beam can be calculated using the formula σ = Mc/I, where σ is the bending stress, M is the bending moment, c is the distance from the neutral axis to the outermost fiber, and I is the moment of inertia of the cross-sectional area of the beam.

What is the difference between a bolt and a screw?

A bolt is a threaded fastener that is designed to be used with a nut, while a screw is a threaded fastener that is designed to be screwed into a threaded hole. Bolts are typically used in applications where the joint can be disassembled, while screws are used in applications where the joint is permanent.

What is a gearbox?

A gearbox is a mechanical device that is used to transmit power from one rotating shaft to another. It consists of a series of gears that are arranged in a specific configuration to provide a desired speed and torque output.


What are the steps involved in machine design?

The steps involved in machine design are:
a) Identification of the problem and the desired outcome
b) Research and analysis of potential solutions
c) Conceptualization and preliminary design
d) Detailed design
e) Prototype development and testing
f) Manufacturing and production
g) Installation, commissioning and maintenance.

What is meant by the term ‘factor of safety’ in machine design?

Factor of safety is a design parameter that describes the amount of additional load that a machine component can handle beyond its intended maximum load capacity. It is calculated as the ratio of the maximum load that a component can handle to the expected load that it will be subjected to. A higher factor of safety indicates a more robust design and greater margin of safety.

What is the difference between stress and strain?

Stress is a measure of the internal force experienced by a material when subjected to external loading, while strain is the measure of the resulting deformation of the material due to that loading. Stress is typically measured in units of force per unit area (e.g., pounds per square inch), while strain is typically expressed as a percentage of the original length or dimension of the material.

What is the difference between static and dynamic loading in machine design?

Static loading refers to the application of a constant or slowly varying load on a machine component, while dynamic loading refers to the application of a rapidly varying or intermittent load. Static loading is typically easier to design for since the stresses and strains can be easily calculated and analyzed, while dynamic loading requires additional analysis to account for factors such as fatigue and resonance.

What are the most common types of bearings used in machine design?

The most common types of bearings used in machine design are ball bearings, roller bearings, and sleeve bearings. Ball bearings are used when low friction and high precision are required, while roller bearings are used for heavy loads and shock absorption. Sleeve bearings are used for low-speed applications and where lubrication is limited.

What is the purpose of a gear in machine design?

Gears are used in machine design to transmit power and motion from one shaft to another, typically at different speeds and torques. They can also be used to change the direction of rotation, modify torque and speed, and to control the timing of mechanical systems.

What is the difference between a pulley and a gear?

A pulley is a simple machine that is used to change the direction of a force or to transmit power between two shafts, while a gear is used to transmit power and motion between two rotating shafts, typically at different speeds and torques. Pulleys are typically used in conjunction with belts or ropes, while gears are used with meshing teeth.

What are the advantages and disadvantages of using welded joints in machine design?

The advantages of using welded joints in machine design are that they are strong, efficient, and cost-effective. However, they also have some disadvantages, such as the fact that they can be difficult to inspect and repair, and that they can be susceptible to cracking and other forms of failure under certain conditions.

What is meant by the term ‘kinematics’ in machine design?

Kinematics refers to the study of motion and its causes, without considering the forces that cause that motion. In machine design, kinematics is used to study the motion of machine components, including the design and analysis of linkages, gears, and other mechanisms.

What is the difference between a bolt and a screw in machine design?

A bolt is a threaded fastener that is used to join two or more objects together, while a screw is a threaded fastener that is used to hold an object in place or to apply pressure to a surface. Bolts are typically used in conjunction with nuts and washers, while screws are often used in conjunction with threaded holes or inserts. Bolts are designed to withstand high tensile loads, while screws are designed to withstand high shear loads.

What is the purpose of a cam in machine design?

A cam is a mechanical device that is used to convert rotary motion into linear motion or vice versa. It consists of a specially shaped surface that interacts with a follower to create a desired motion. Cams are often used in machine design to control the timing and sequence of mechanical operations, such as in engines, pumps, and machines that require precise motion control.

What is the difference between a belt drive and a chain drive in machine design?

A belt drive is a system that uses a belt to transmit power and motion between two rotating shafts, while a chain drive is a system that uses a chain to transmit power and motion. Belt drives are typically quieter, more efficient, and require less maintenance than chain drives. However, chain drives are generally more durable and can handle higher loads.

What is the difference between a linear actuator and a rotary actuator in machine design?

A linear actuator is a device that creates linear motion or force, while a rotary actuator is a device that creates rotary motion or torque. Linear actuators are often used in machine design to control the movement of machine components, such as in robotics or automation systems. Rotary actuators are often used to rotate or move machine components, such as in engines, pumps, or machine tools.

What is meant by the term ‘tolerance’ in machine design?

Tolerance refers to the allowable variation in dimensions or other characteristics of a machine component. It is used to ensure that parts fit together properly and function as intended. Tolerance can be specified as a range of allowable variation, or as a specific value that a dimension must fall within.

What is the purpose of a bearing in machine design?

Bearings are used in machine design to reduce friction and wear between moving parts. They provide a low-friction interface between rotating or sliding surfaces, allowing for smooth and efficient motion. Bearings can also help to absorb shock and reduce vibration, and can improve the overall durability and reliability of a machine.

What is the difference between a pneumatic and hydraulic system in machine design?

Pneumatic systems use compressed air to transmit power and motion, while hydraulic systems use fluids such as oil or water. Pneumatic systems are often used in applications where cleanliness is important or where high speeds and low forces are required, such as in packaging machinery. Hydraulic systems are often used in applications where high forces and precise control are required, such as in heavy machinery or industrial presses.

What is the purpose of a gearbox in machine design?

A gearbox is a mechanical device that is used to transmit power and motion between rotating shafts. It consists of a series of gears that mesh together to change the speed, torque, or direction of motion. Gearboxes are often used in machine design to increase or decrease the speed of a motor or to transmit power between machines that are located far apart.

What is meant by the term ‘stress’ in machine design?

Stress is a measure of the internal forces that are generated within a machine component when it is subjected to an external load or force. It is often expressed as a force per unit area, such as pounds per square inch (psi) or newtons per square meter (N/m2). High levels of stress can cause machine components to fail, and designers must take into account the expected loads and stresses when designing machine components.

What is the difference between a stepper motor and a servo motor in machine design?

A stepper motor is a type of motor that moves in small, precise steps in response to digital signals, while a servo motor is a type of motor that rotates continuously in response to analog signals. Stepper motors are often used in applications that require precise control of position or speed, such as in robotics or CNC machines. Servo motors are often used in applications that require smooth and continuous motion, such as in industrial automation or motion control systems.

What is meant by the term ‘mechanical advantage’ in machine design?

Mechanical advantage refers to the ratio of the output force to the input force in a machine. It is a measure of how much a machine amplifies or multiplies the force applied to it. Mechanical advantage is often used in machine design to increase the force or speed of a machine, or to reduce the amount of force required to perform a particular task.

What is the purpose of a clutch in machine design?

A clutch is a mechanical device that is used to connect or disconnect two rotating shafts. It allows for smooth engagement and disengagement of power transmission, such as between an engine and a transmission in a vehicle. Clutches are often used in machine design to protect the drivetrain from excessive loads, to allow for gear changes, or to enable the machine to be started or stopped smoothly.

What is the difference between a closed-loop and open-loop control system in machine design?

A closed-loop control system uses feedback from sensors to adjust the output of a machine in response to changes in the environment or the load. An open-loop control system does not use feedback and relies on predetermined input signals to control the machine. Closed-loop systems are often used in machine design to achieve greater accuracy, stability, and reliability, while open-loop systems are simpler and less expensive.

What is meant by the term ‘moment of inertia’ in machine design?

Moment of inertia is a measure of an object’s resistance to changes in rotational motion. It is a function of an object’s mass and distribution of mass around its axis of rotation. Moment of inertia is often used in machine design to determine the amount of torque required to accelerate or decelerate a rotating component, or to predict the behavior of a rotating system under different conditions.

What is the purpose of a shock absorber in machine design?

A shock absorber is a mechanical device that is used to absorb and dampen the energy of an impact or vibration. It can help to protect machine components from damage, reduce noise and vibration, and improve the overall performance and safety of a machine. Shock absorbers are often used in applications such as automotive suspension systems, industrial machinery, and aerospace equipment.

What is the difference between a rigid and flexible coupling in machine design?

A rigid coupling is a mechanical device that is used to connect two rotating shafts in a fixed position, while a flexible coupling is a device that allows for some degree of misalignment or movement between the shafts. Rigid couplings are often used in applications where precise alignment is required, such as in precision machine tools. Flexible couplings are often used in applications where some degree of movement or misalignment is expected, such as in vehicles or machines that operate under varying loads or conditions.

What is meant by the term ‘tensile strength’ in machine design?

Tensile strength is the maximum amount of stress that a material can withstand before it fractures or breaks. It is often expressed in units of force per unit area, such as pounds per square inch (psi) or megapascals (MPa). Tensile strength is an important property to consider in machine design, as it determines the maximum load that a machine component can withstand before it fails.

What is the purpose of a bearing in machine design?

A bearing is a mechanical device that is used to reduce friction between two moving surfaces, such as rotating shafts or linear guides. It allows for smooth and efficient motion, while also supporting the load of the machine component. Bearings are often used in machine design to reduce wear and tear, increase efficiency, and improve the overall performance and reliability of the machine.

What is the difference between a linear and rotary actuator in machine design?

A linear actuator is a device that converts rotary motion into linear motion, while a rotary actuator is a device that converts linear motion into rotary motion. Linear actuators are often used in applications such as robotics, linear motion systems, and industrial automation. Rotary actuators are often used in applications such as robotic arms, valves, and other mechanical systems that require rotary motion.

What is meant by the term ‘thermal expansion’ in machine design?

Thermal expansion is the tendency of materials to expand or contract in response to changes in temperature. It is an important consideration in machine design, as it can cause components to deform or fail if not properly accounted for. Thermal expansion can be minimized through the use of materials with low coefficients of thermal expansion, as well as through the use of design techniques such as compensation and thermal isolation.

What is the purpose of a flywheel in machine design?

A flywheel is a mechanical device that is used to store energy and provide rotational inertia to a machine. It can help to smooth out fluctuations in power output, reduce the effects of mechanical shock or vibration, and maintain a steady speed or output. Flywheels are often used in applications such as engines, generators, and other machines that require a steady and reliable power source.

What is the difference between a bolt and a screw in machine design?

A bolt is a fastener that is used to join two or more components together, while a screw is a fastener that is used to hold two or more components together by exerting pressure on them. Bolts typically have a threaded shank with a head at one end and a nut at the other end, while screws have a threaded shank with a pointed or flat head. Bolts are often used in applications where a removable connection is required, while screws are often used in applications where a permanent connection is desired.

What is meant by the term ‘creep’ in machine design?

Creep is the tendency of materials to deform or change shape over time when subjected to a constant load or stress. It is an important consideration in machine design, as it can cause components to fail or lose their functionality if not properly accounted for. Creep can be minimized through the use of materials with high strength and stiffness, as well as through the use of design techniques such as reinforcement and stress analysis.

What is meant by the term ‘torsional stiffness’ in machine design?

Torsional stiffness is the ability of a material or component to resist deformation or twisting when subjected to a torque or rotational force. It is an important consideration in machine design, as it determines the amount of torsional deformation or deflection that a machine component can withstand before it fails or loses its functionality. Torsional stiffness can be increased through the use of materials with high shear modulus, as well as through the use of design techniques such as cross-sectional shape and reinforcement.

What is the purpose of a gearbox in machine design?

A gearbox is a mechanical device that is used to increase or decrease the speed or torque of a rotating shaft. It can help to improve the efficiency, performance, and control of a machine, as well as protect the drivetrain from excessive loads or shocks. Gearboxes are often used in applications such as vehicles, industrial machinery, and power transmission systems.

What is meant by the term ‘stress concentration’ in machine design?

Stress concentration is the phenomenon of increased stress or strain at a localized point in a material or component, often caused by irregularities or geometric features such as notches, holes, or fillets. It is an important consideration in machine design, as it can significantly reduce the strength and durability of a component and lead to premature failure. Stress concentration can be minimized through the use of design techniques such as smoothing, reinforcement, and proper selection of materials and geometries.

What is the purpose of a belt drive in machine design?

A belt drive is a mechanical device that is used to transmit power and motion between two rotating shafts. It can help to transfer torque and speed efficiently, while also reducing shock and vibration in the drivetrain. Belt drives are often used in applications such as engines, pumps, and other mechanical systems that require smooth and reliable power transmission.

What is meant by the term ‘fatigue’ in machine design?

Fatigue is the phenomenon of gradual and progressive damage to a material or component caused by repeated loading and unloading cycles. It is an important consideration in machine design, as it can significantly reduce the strength and durability of a component and lead to premature failure. Fatigue can be minimized through the use of design techniques such as stress analysis, material selection, and surface treatment.

What is the purpose of a heat exchanger in machine design?

A heat exchanger is a mechanical device that is used to transfer heat between two fluids or gases, often to regulate temperature or increase energy efficiency. It can help to maintain a steady and controlled temperature, while also reducing the energy required for heating or cooling. Heat exchangers are often used in applications such as engines, refrigeration systems, and industrial processes.

What is meant by the term ‘shear strength’ in machine design?

Shear strength is the maximum amount of stress that a material can withstand before it fractures or breaks due to shear forces. It is an important consideration in machine design, as it determines the maximum load that a machine component can withstand before it fails. Shear strength can be increased through the use of materials with high shear modulus and strength, as well as through the use of design techniques such as reinforcement and cross-sectional shape.


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