(a-i) If the power source characteristic in a Metal Inert Arc welding process is Vp = 38 – I⁄60 and the arc characteristic is Va = 3La + 27, calculate the change in arc power when arc length changes from 1 mm to 3 mm. Also find the maximum arc length sustainable when source current limit is 300 A.
(a-ii) An EDM process cuts a 6 mm deep cavity in high-carbon steel using (I) copper–tungsten and (II) copper electrodes. Taking wear ratios 9 : 1 and 3 : 1 respectively, determine the required spindle movement.
(b-i) In ECM a 15 mm diameter, 125 mm deep hole is to be drilled in high-carbon steel. With 45 A current and 15 % NaCl electrolyte, find the machining time. Take valency of Fe = 2, atomic weight 56, density of steel 7·8 g cm⁻³.
(b-ii) Using ECM to machine Nimonic-75 alloy (composition table given) and the lowest valency of dissolution for each element (data table given), compute the material-removal rate when current is 1050 A.
(c) With a line diagram explain the different flow patterns used in plant layouts. State the conditions that must be satisfied by an ideal flow pattern.