A $$\phi \,\,25$$ $$mm$$ hole is pierced in a $$t=2.5mm$$ thick steel sheet having shear strength $$\tau = 350\,\,MPa.$$ If the diametral clearance is given by the expression $$C=0.0064$$ $$t$$ $$\sqrt \tau ,$$ the die diameter (in $$mm$$), punch diameter (in $$mm$$) and punch force in $$(kN)$$ respectively are

Determine the load required to punch a $$20$$ $$mm$$ diameter hole in $$2$$ $$mm$$ thick sheet. The properties of the material of the sheet are:
Tensile strength $$-580$$ $$MPa;$$
Yield strength in tension $$-410$$ $$MPa$$
Shear strength $$-350$$ $$MPa;$$
Yield strength in shear $$-250$$ $$MPa$$

The load in $$kN$$ is:

In deep drawing of sheet metal, spring loaded stripper clamps the work until:

A hole of $$40$$ $$mm$$ diameter is pierced in a steel sheet of $$4$$ $$mm$$ thickness without shear on the tool. Shear strength of steel is $$400$$ $$N/m{m^2},$$ and penetration is $$25\% .$$ What is the expected percentage load reduction if a shear of $$1$$ $$mm$$ is provided on the punch?