A new testing machine to determine the behaviour of aluminium granulate under combined pressure and shear

To reduce the environmental impact and increase the yield from conventional aluminium recycling processes, a direct continuous extrusion method of shredded scrap is being developed. The innovative method is a process where a rotating screw generates the extrusion pressure, introducing rotation to the scrap compacting and extruding in one single operation. The objective of this paper is to present a testing machine, representing the basic mechanisms of the above process in a simplified manner. A rotary anvil-type machine, which is capable of imposing rotational and linear translations, has been built for the purpose of compacting granulate under different pressures, torques and strain rates at different temperatures. This paper describes the developed machine, its features and capabilities in detail. The machine has shown that it is capable of delivering a compressive force of 500 kN while simultaneously delivering a torque of 1.580 Nm on disks made from aluminium granulate. Several tests, with and without rotation, have been carried out where aluminium granulate has been consolidated. The material used was an aluminium alloy AA6060 wire cut in appropriate sizes. The results show how simultaneous rotation and compression reduce the necessary pressure needed for achieving full compactation of the granulate. It is also shown how an increased number of rotations influence the mixing of the granulate to a greater depth. The severe plastic deformation of the granulate is thought to influence the mechanical properties of the resulting compound beneficially.