engineering recuitment GATE ME 2023-24 Test Series Production Engineering (Manufacturing) Metal Forming Extrusion
A billet of 75 mm long & 25 mm in diameter is to be extruded in a direct extrusion operation to a diameter of 12.5 mm. The extrudate has a round cross-section. If the work material has an average flow stress of 373 MPa. The pressure at end of billet is given as: -
\(P = {Y_{avg}}\left( {{\varepsilon _x} + \frac{{2L}}{{{d_0}}}} \right)\)
where εx is extrusion strain, L ÷ remaining length of billet to be extruded & d0 initial diameter. εx is given by Johnson formula a +b lnR, where a, b : Johnson’s constant & R extrusion ratio. Find the ram force at the time when 15 mm billet has been extruded. Take Johnson’s constant a = 0.8 & b = 1.51
351.52 kN
2
1406.07 kN
3
1625.78 kN
4
406.44 kN