Tailor Blank Casting—Control of sheet width using an electromagnetic edge dam in aluminium twin roll casting

•Electromagnetic edge dam used to vary sheet width during twin roll casting.•Step change in sheet width from 130mm to 80mm and back was demonstrated.•Strength and stiffness of magnetic field were measured.•No change in sheet surface quality but mechanical properties were improved.•Mechanisms for operation of the electromagnetic edge dam are proposed. A significant fraction of all sheet aluminium is scrapped during manufacture because the supply chain is configured to produce long coils of strip with constant width while end products are formed from irregularly shaped non-tessellating blanks. In this paper, an opportunity to reduce this rate of scrap is explored. Electro-magnetic edge-dams have been used previously to contain the melt in twin-roll strip casting of aluminium but here, equipment has been designed to allow rapid movement of such an edge dam during casting. This is named ‘Tailor Blank Casting’. The equipment is described and the first experimental trials are presented, with one edge of the melt constrained by a moving electro-magnetic dam in order to achieve a controlled variation in sheet width. The trials demonstrated successful containment of the liquid prior to solidification, and a sheet with close to step changes in width was cast. From analysis of the results of these trials, the mechanisms of width change are proposed and the effect of the moving dam on product properties is studied. The paper concludes with a discussion about possible yield savings and the next steps for further development of the process.