An Investigation of the Material Flow in a Screw Extruder of Aluminium Using Contrast Material

Abstract:

The material flow in a screw extruder of aluminium was investigated. Screw extrusion of aluminium is a new solid state process where granulate aluminium is consolidated and extruded in a single continuous process using a rotating screw as the pressure generating device. Understanding the material flow is vital for predicting the consolidation and welding process thereby making it possible to optimize screw and container design to increase the capacity, ekstrudate quality and process stability. Using a prototype screw extruder, aluminium alloy AA6060 was extruded together with contrast material using different feeding schemes to visualize the material flow. Material left in the extruder was inspected visually, sectioned and etched in NaOH to reveal the interaction between the contrast material and the AA6060. It was found that newly fed contrast material primarily displaced material in the centre of the screw channel and the extrusion chamber hereby revealing the main paths of the material flow. Areas of sticking friction, material dead zones and zones of slow material displacement rate were effectively identified using this method.

• Periodical: Key Engineering Materials (Volumes 504-506)
• Pages: 475-480
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.504-506.475
• Online since: February 2012
• Authors: Fredrik Widerøe, Togeir Welo
• Keywords: Contrast Material, Material Flow, Screw Extrusion, Solid State Recycling

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