AD POLYTECHNIC Manufacturing Processes

Homework 4

1) Determine the shape factor for each of the extrusion die orifice shapes in the figures
below
(a) rectangular bar, (b) tube, (c) channel, and (d) cooling fins.

2) A cylindrical billet that is 100 mm long and 50 mm in diameter is reduced by indirect
(backward) extrusion to a 20 mm diameter. The die angle is 90°. The Johnson
equation has a = 0.8 and b = 1.4, and the flow curve for the work metal has a
strength coefficient of 800 MPa and strain hardening exponent of 0.13.
Determine (a) extrusion ratio, (b) true strain (homogeneous deformation), (c) extrusion
strain, (d) ram pressure, and (e) ram force.