Manufacturing Science - Short Answer Questions from AMIE Exams (Summer 2020)

Answer the following questions

Define ductility

Ductility is the physical property of the metal which means if we pull the metal it’s going to stretch rather than break. In other words, a material’s ability to undergo significant plastic deformation under tensile stress before rapture is called the ductile properties of the material. The ductile materials are nickel, copper, steel etc.  

Factors affecting tool life

  • Cutting Speed
  • Physical Properties of Work Piece
  • Area of Cut
  • Ratio of Feed to Depth of Cut (f/d)
  • Shape and Angles of Tools
  • Effect of Lubricant
  • Nature of Cutting

Wheel dressing

Dressing returns the grinding wheel to its original sharpness by removing old grains to reveal the fresh grain underneath. It removes clogs, dulled abrasive grains, and excess bonding material to help minimize vibration, thereby improving surface finish.

Sprue well

Sprue – a hole where the metal enters the mould. It is ideally tapered to prevent air from entering the casting. Well – forms a cushion for the metal pouring through the sprue so the sand is not washed into the casting

Taylor’s tool life equation

Taylor's tool life equation As per F.W. Taylor, the relationship between Cutting Speed and Tool Life can be expressed as

VTn = C

Where
V = Cutting speed (m/min) 
T = Tool life (minutes) 
n = a constant whose value depends upon the material of the cutting tool & job, called tool life Index. 
(Commonly, n = 0.08 to 0.02 for H.S.S tools, n = 0.2 to 0.4 for cemented carbide tools, n = 0.5 to 0.7 for Ceramic Tools, n = 0.1 to 0.15 for cast alloys)
C = a constant, called machining constant

Material removal in EDM

In EDM, material removal is performed by applying a pulsating (ON/OFF) high-frequency current through the electrode to the workpiece. This removes (erodes) very tiny pieces of material from the workpiece at a controlled rate. The electrode and the workpiece are both immersed in a liquid called dielectric fluid.

The function of the flux in submerged Arc Welding

The functions of the flux are: to assist arc striking and stability. to form a slag that will protect and shape the weld bead. to form a gas shield to protect the molten filler metal being projected across the arc gap.

Extrusion

Extrusion is a process where a material undergoes plastic deformation by the application of a force causing that material to flow through an orifice or die. The material adopts the cross-sectional profile of the die and if the material has suitable properties, that shape is retained in the final extrudate.

Wire drawing

Wire drawing is a metalworking process used to reduce the cross-section of a wire by pulling the wire through a single, or series of, drawing die(s). There are many applications for wire drawing, including electrical wiring, cables, tension-loaded structural components, springs, paper clips, spokes for wheels, and stringed musical instruments. Although similar in process, drawing is different from extrusion, because in drawing the wire is pulled, rather than pushed, through the die.

Fusion Welding

Fusion welding is a process that uses heat to join or fuse two or more materials by heating them to a melting point. 



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