Finite element investigations upon the influence of pocket die designs on metal flow in aluminium extrusion: Part I. Effect of pocket angle and volume on metal flow

In extrusion die design, it has become increasingly common to use “pocket” technology to balance the metal flow. The balance of metal flow is particularly important for multiple cavity dies or sections with varying thickness in order to maintain a uniform velocity profile across the face of the die and thus minimise distortion of the extrudate. However, the fundamental understandings of pocket design are currently very limited. In this study, results are presented from a series of pocket designs that were modelled using finite element method (FEM) to systematically investigate the influence of the pocket design parameters on the metal flow. In part I of this study, the effects of pocket angle and size on metal flow were investigated and it is shown that pocket angle plays an important role influencing metal flow velocity, whilst pocket volume has much less effect on velocity. The investigation is mainly focused on developing a qualitative understanding of pocket designs.