The ratio of press force required to punch a square hole of $$30$$ $$mm$$ side in a $$1$$ $$mm$$ thick aluminium sheet to that needed to punch a square hole of $$60$$ $$mm$$ side in a $$2$$ $$mm$$ thick aluminium sheet is________.

Circular blanks of $$10mm$$ diameter are punched from an aluminium sheet of $$2$$ $$mm$$ thickness. The shear strength of aluminium is $$80$$ $$MPa.$$ The minimum punching force required in $$kN$$ is

Match the following metal forming processes with their associated stresses in the Work-piece