A new process proposal for continuous fabrication of rheological material by rotational barrel with stirring screw and its microstructural evaluation

A new rheological fabrication process with specially designed rotational-barrel-type equipment has been developed for a rheo die-casting and a rheoforming process to reduce the number of manufacturing processes for the production of various engineering parts. The rotational-barrel-type equipment, which can continuously fabricate rheological material, was specially designed to have a shear rate and temperature control functions. While the barrel was constantly rotated at a constant temperature, the shear rate is controlled by the rotation speed. The effect of this system on the microstructure by varying the shear rate, the cooling rate and rotation time using A356.2 aluminum alloy was widely examined and analyzed, and suitability for new equipment for rheoforming process was investigated. It was resulted that the higher rotation speed, the longer time of rotation, and the slower cooling rate, the smaller the equivalent diameter and the roundness of primary particle were. However, it was confirmed that grain agglomeration and increase in grain size happens above the rotational time of 1800 s. (C) 2008 Elsevier B.V. All rights reserved.