Terfa Gundu^1,, Livinus Tuleun¹, Oryina Injor¹

In this paper, an extensive direct extrusion program was designed to experimentally investigate the effects of die bearing geometry parameters with a view to achieving reduced extrusion loads and product deflection. Using soft aluminiumalloy as extrusion material, flat and conical pocket die bearing geometries were considered, and geometry parameters of die angle, bearing length, pocket depth and offset were varied to obtain corresponding responses of extrusion pressure and extrude deflection. Results showed that for conical pocket geometry, increasing entrant angle reduced extrusion pressure to a minimum value at the included die angle of 90°, and then increased gradually with further increase in die angle. Extrudes deflections are reduced as die angle is increased. Increasing the die bearing length increased extrusion pressure but extrudes deflection is reduced. For flat pockets, increasing the pocket depth increased extrusion pressure, but for conical pockets, extrusion pressure is reduced. For both geometries, extrudes deflection is reduced as pocket depth is increased. Both extrusion pressure and extrudes deflection are reduced increasing pocket offset. It is concluded that extrusion pressure and extrudes deflection can be controlled using these die geometry parameters. Better flow conditions are however obtained with conical die geometries to achieve minimized extrusion loads and product curvature.

extrusion pressure, extrudes deflection, die bearing geometry, die angle, bearing length, pocket depth, pocket offset