Scrap Prediction in Direct Extrusion

The continuous, direct extrusion is an economical and efficient process to manufacture high-quality aluminum profiles. However, because of multiple billets processing, transient defects (coring and charge welds) can be generated, affecting portions of the profiles and deteriorating their mechanical properties. In the case of structural applications, the reliable prediction of the onset and the extent of these portions is therefore mandatory to be scrapped by the commercialized length. In this context, the present work has been aimed at examining the dynamic evolution of the coring and charge weld defects in the direct extrusion of a solid profile. Both experimental and numerical activities have been performed, and results evaluated in terms of coring and charge weld defects evolution achieving good agreement for both phenomena. Results have been compared with the outcomes of the analytical models available in the literature. For the charge weld extension, the analytical model returned poor predictably, while a very good match with numerical data was obtained for the coring defect.