Fundamentals of Metal Forging Review Questions Flashcards Preview

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Flashcards in Fundamentals of Metal Forging Review Questions Deck (10)
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What are the difference between bulk deformation processes and sheet metal processes

Bulk deformation processes are characterized by significant deformations and massive shape changes, and surfacearea-to-volume of work is small


Sheet Metal working are formal cutting oeprations performed on metal sheets, coils, strips. Surfacearea-to-volume ratio of starting metal is high


Describe extrusion

A compression process in which the work metal is forced to flow through a die opening, thereby taking the shape of the opening as its own cross section


Why is the term pressworking often used for sheet metal processes

Term applied to sheetmetal working ops because the machine sused to perform these ops are presses


Difference between deep drawing and bar drawing

Deep drawing is continous while bar drawing cuts the section into separate pieces


Mathematical equation for flow curve

Flow stress = strength coefficient (strain) ^ strain hardening exponent


How does increasing temeprature affect the parameters of the flow curve

For metals, the value of the strength coefficient and the shear exponent depend on temperature.


strength and strain hardening are reduced at higher temp, requiring lower forces and power during forming


Indicate some advantages of cold working relative to warm and hot working

  • greater accuracy
  • better surface finish
  • higher strength and hardness of part due to strain hardening
  • grain flow during deformation provides oppotunity for desirbale directional properties to be obtained
  • no heating required


What is isothermal forming

forming oeprations that are carried out in such a way as to eliminate surface cooling and the resulting thermal gradients in the workpart


accomplished by preheating tools


Why is friction generally undesirable in metal forming

  • metal flow in work is retarded, casuing residual stresses amd defects
  • forces and power to perform increases
  • tool wear


what os sticking friction in metalworking

tendency of two surfaces in relative motion to adhere to each other rather than slide


friction stress between the surfaces exceed the shear flow stress of work metal, causing metal to deform by a shear process beneath the surface rather than slip at the surface