The Dynamics of the Dead Zones in Hot Extrusion
Chris Jowett, Consultant for Ingot Sales, Rio Tinto Alcan,
Nick Parson, and Raynald Guay, Sebastien Fafard and Alexandre Maltais:
Rio Tinto Alcan, Arvida R & D Centre, Québec, Canada, and Jean-Francois Beland,
Aluminium Technology Centre, Chicoutimi, Québec, Canada.
Track: EXTRUSION/DIE PRACTICAL
ABSTRACT --- It is generally accepted that the best extruded surface finishes, such as are
required with bright trim AA6463 profiles, can be produced with flat dies that do not incorporate
any welding chamber. This is thought to be due to several possible factors: the ability to lubricate
the front face of each billet; increased cooling of the die bearing during the dead cycle; and more
efficient removal of the aluminum build-up on the die bearings between billets. Another
consideration is the affect of the material that accumulates in the welding chambers. This material
is considered dead, but there is a belief that the dead zones in the die are dynamic, and the
contamination from the surface and ends of preceding billets can feed into the extrusions’ surface
during an order. The work reported in this paper examines the dynamics of the dead zones
through the use of tracers, and looks at the effect of solid die feeder plate geometry.
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