500-mm long aluminium billets of 250-mm diameter are separately
forward extruded into bars of 125-, 50-, 25-, and 12.5-mm diameter at 500°C
using a ram speed of 0.75 m/min. Flow rule is defined through C = 14 MPa,
and m = 0.22 with ?f0 = 35 MPa. The die angle is 2? = 140° whereas the Coulomb
coefficient of friction is 0.08.
a) Determine the extrusion force through the analytical approach for the
four bar diameters,
b) Determine the extrusion force through the empirical approach for the
four bar diameters,
c) Compute the exit velocities of the extrusions in the four cases,
d) Figure out the ram speed that will give an analytical extrusion force of
4000 kN for the bar with 12.5 mm diameter, and
e) Elaborate on whether the press is feasible enough for the economical
extrusion of bars of these sizes.