In a $$DC$$ $$arc$$ welding operating, the length characteristic was obtained as $${V_{arc}} = 20 + 5l$$ where the $$arc$$ length $$l$$ was varied between $$5mm$$ and $$7mm.$$ Here $${V_{arc}}$$ denotes the arc voltage in volts. The $$arc$$ current was varied from $$400A$$ to $$500A.$$ Assuming linear power source characteristic, the open circuit voltage and the short circuit current for the welding operation are

In a shaping process, the number of double strokes per minute is $$30$$ and the quick return ratio is $$0.6,$$ If the length of the stroke is $$250mm,$$ the average cutting velocity in $$m/min$$ is

In a single pass drilling operation, a through hole of $$15$$ $$mm$$ diameter is to be drilled in a steel plate of $$50mm$$ thickness. Drill spindle speed is $$500epm,$$ feed is $$0.2mm/rev$$ and drill point angle is $${118^ \circ }.$$ Assuming $$2mm$$ clearance at approach and exit, the total drill time (in seconds) is

A $$CNC$$ vertical milling machine has to cut a straight slot of $$10$$ $$mm$$ width and $$2$$ $$mm$$ depth by a cutter of $$10$$ $$mm$$ diameter between points $$(0, 0)$$ and $$(100, 100)$$ on the $$XY$$ plane (dimensions in $$mm$$). The feed rate used for milling is $$50$$ $$mm/min.$$ Milling time for the slot (in seconds) is