Design & Manufacturing - short answer questions from AMIE exams (Winter 2021)

Answer the following in brief ( 2 x 100)

State and explain Concurrent Engineering.

Simultaneous (concurrent) Engineering - A way of simultaneously designing products, and the processes for manufacturing those products, through the use of cross-functional teams to assure manufacturability and to reduce cycle time.

Give an example of a design for maintenance.

Design for Maintainability (DfM) is the practice of integrating operations and maintenance considerations into project planning and design to achieve effectiveness, safety, and economy of maintenance tasks during the lifespan of a facility. 

For example, replacing all the fluorescent lights in an office once a year can be cheaper than replacing lights individually as they fail, because labor is used more efficiently. Since maintainability is designed in, it is important to specify both reliability and maintainability targets early in the design cycle.

Differentiate between hot forging and cold forging.

The cold forging manufacturing process increases the strength of a metal through strain hardening at a room temperature. On the contrary the hot forging manufacturing process keeps materials from strain hardening at high temperature, which results in optimum yield strength, low hardness and high ductility.
 

State the functions of electrolytes in ECM.

Electrolytes are substances that become ions in solution and acquire the capacity to conduct electricity. The electrolyte has three main functions in the ECM process. 
  • It carries the current between the tool and the workpiece, 
  • it removes the product of the reaction from the cutting region, and 
  • it removes the heat produced by the current flow in the operation. 
Electrolytes must have high conductivity, low toxicity and corrosivity, and chemical and electrochemical stability. 

Differentiate between orthogonal cutting and oblique cutting.

Orthogonal Cutting
  • The cutting angle of tool make right angle to the direction of motion.
  • The chip flow in the direction normal to the cutting edge.
  • In orthogonal cutting only two components of force considered cutting force and thrust force which can be represent by 2D coordinate system.
  • This tool has lesser cutting life compare to oblique cutting.
  • The shear force act per unit area is high which increase the heat developed per unit area.
  • The chips flow over the tool.
Oblique Cutting
  • The cutting angle of tool foes not make right angle to the direction of motion.
  • The chips make an angle with the normal to the cutting edge.
  • In oblique cutting three component of force are considered, cutting force, thrust force and radial force which cannot represent by 2D coordinate. It used 3D coordinate to represent the forces acting during cutting, so it is known as 3D cutting.
  • This tool has higher cutting life.
  • The shear force per unit area is low, which decreases heat develop per unit area hence increases tool life.
  • The chips flow along the sideways.

 

What is the purpose of lapping?

Lapping is a machining process in which two surfaces are rubbed together with an abrasive between them, by hand movement or using a machine. It is a process reserved for products that demand very tight tolerances of flatness, parallelism, thickness or finish.
 

Differentiate between design verification and validation.

Validation is focused on establishing the design's accuracy and reliability in relation to the user's demands. This is the step in which you construct a version of the product and evaluate it against the customer’s requirement.

Design verification is a process that examines and shows proof to certify that the outcome of a specified software product satisfies the input requirements.

Differentiate between soft automation and hard automation.

The main difference between hard and soft automation is that hard automation requires physical changes to improve functionality while soft automation machines are programmed through a computer interface.

State the concept of robust design.

Robust product design is a concept from the teachings of Dr. Genichi Taguchi. It is defined as reducing variation in a product without eliminating the causes of the variation. In other words, making the product or process insensitive to variation.

Examples of robust design include umbrella fabric that will not deteriorate when exposed to varying environments (external variation), food products that have long shelf lives (internal variation), and replacement parts that will fit properly (unit-to-unit variation).
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