In a cutting test with $$0.3mm$$ flank wear as tool failure criterion, a tool life of $$10min$$ was obtained at a cutting velocity of $$20m/min.$$ Taking tool life exponrent as $$0.25,$$ the tool life in minutes at $$40m/min$$ of cutting velocity will be

A single point cutting tool with $${12^0}$$ rake angle is used for orthogonal machining of a ductile material. The shear plane angle for the theoretically minimum possible shear strain to occur