Two sheets of low carbon steel $$1.5mm$$ thick each are spot welded by passing a current $$10000$$ amps for $$5$$ cycles in $$50$$ $$Hz$$ main supply.

i) What is the heat generated due to the supply of power if effective resistance has $$200$$ micro ohms,

ii) The maximum indentation is $$10\% $$ of sheet thickness and density of the spot weld nugget $$8$$ $$gm/cc.$$ If $$1380$$ Joules are required to melt $$1gm$$ of steel, determine heat required for welding operation if $$D=6SQRT$$ $$(t)$$ to determine nugget diameter $$D$$ and assume the nugget size to be equal to metal between the two electrodes

In $$MIG$$ welding the power source characteristics is $${V_p} = 36 - {\rm I}/60$$ and the arc characteristics is $${V_a} = 2{L_a}\,\,\,\, + 27.$$ Find the change in power of the arc if the arc length changed from $$2mm$$ to $$4mm.$$ If the maximum current capacity of the power source is $$300$$ Amps, the maximum arc length sustainable is

A blind hole is better tapped with a tap having

Find the speed range ratio for the drilling machine spindle if the minimum and maximum diameters of drills used are $$5$$ $$mm$$ and $$25$$ $$mm$$ respectively and if the machinability indices for the work materials are $$120$$ (brass) and $$40$$ (alloy steel)