Planar-flow melt spinning (PFMS) is a single-stage rapid manufacturing technique for producing thin metal sheets or ribbons. Commercial acceptance of PFMS requires ribbons to be cast with uniform thickness to tolerance. The process feeds molten metal through a nozzle onto a moving wheel where a puddle is formed and from which a continuous ribbon is 'spun'. This study focuses on the time dependent behavior of the process. The dynamics of the process are modeled using unsteady mass balances, combined with a Bernoulli model of flow. Variations over a number of time scales are observed. The time scale over which the process can be treated as 'quasi-steady' is identified. Measuring the evolution of the puddle length and ribbon thickness within a cast indicates that the solidification rate also varies with time and a maximum in solidification rate is inferred. (C) 2010 Elsevier Ltd. All rights reserved.