Calculate the minimum number of hot rolling passes necessary to reduce an ingot of $$200mm$$ thickness to $$100mm$$ thickness in two high reversible rolling mill with roll diameter is $$500$$ $$mm.$$ The coefficient of friction between the rolls and the hot material is assumed as $$0.20.$$

The maximum interference in $$mm$$ after assembly between a bush of size $${30^{\matrix{ { + 0.06} \cr { + 0.03} \cr } }}$$ and a shaft of size $${30^{\matrix{ { + 0.04} \cr { - 0.02} \cr } }}$$ is

Holes $$1,2,3,4$$ drilled in sequence , with angular positions and tolerances are shown in Figure. Evaluate closing angle $$'X'$$ with its tolerance band.