DEVELOPMENT OF THE TWIN-ROLL CASTING PROCESS

Twin-roll casting has been used for approximately 40 years for the pro duction of aluminium strip. Traditionally, the process has been one of low productivity and has been restricted to a limited range of alloys and a minimum cast thickness of approximately 6 mm. Moreover, strip p roduced by this process is susceptible to a number of characteristic c asting defects. Despite these limitations, the technique is inherently sound and the current paper describes a development programme that ha s largely overcome some of the shortcomings of the traditional process . Casting thin (typically 1-2 mm) has the advantage of reducing the do wnstream processing requirement and in addition it has been demonstrat ed that significant increases in productivity are possible for a wide range of alloys. However, the increased exit temperatures and increase d separating forces associated with casting at thin gauges result in a n increase in the tendency for the cast strip to stick to the easter r olls. The phenomenon of sticking is described and a number of methods of overcoming the problems are discussed.