Q1. [50%] 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.
Continue to next page for Q2.
Middle East Technical University – Northern Cyprus Campus
MECH303 • 2019-20 SPRING • TAKE-HOME EXAM 2
Lecturer: Dr Volkan Esat
Q2. [50%] A cooking pot in the form of a cylindrical container is to be
manufactured; first by blanking a circular sheet; secondly, deep drawing a cup;
and finally, reducing the wall-thickness. The required final dimensions are 200-
mm outer diameter, 160-mm overall height of cup, 2-mm wall, and 5-mm base
thicknesses (ignore the fillet between the base and the wall). The material is
5052-H24 Al alloy (UTS = 260 MPa). Check the feasibility of the process as
follows:
a) Draw sketches of the process stages,
b) Assuming that the wall thickness of the container in the initial deep
drawing stage is the same as the starting sheet thickness, determine the
diameter of the starting blank,
c) Compute the blanking force,
d) Check whether the first deep drawn container can be made in a single
draw. If not, how can the new process sequence be?
e) Determine the punch diameter for the initial deep drawing stage, and
calculate the drawing force, and
f) Identify two manufacturing methods for the final reducing the wallthickness stage.

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