Workshop Technology
Piercing is an operation of cutting

A number of holes evenly spaced in a regular pattern on a sheet of metal
A hole (other than cylindrical) in a sheet of metal by the punch and the die
A flat sheet to the desired shape
A cylindrical hole in a sheet of metal by the punch and the die

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Workshop Technology
During hot working of metals

Mechanical properties are improved due to refinement of grains
All of the listed here
Grain structure of the metal is refined
Porosity of the metal is largely eliminated

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