An experimental study of process behavior in planar flow melt spinning
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INTRODUCTION
SINGLE roll melt spinning (SRMS) is a process which is used to cast sheet forms of materials. Figure 1 is a schematic of three common types of SRMS.E~.2~ In this type of process, a molten material (usually metallic) is introduced onto a spinning wheel. The material is then dragged out to produce long filaments, usually in the form of wide ribbons. Using the SRMS technique for the mass production of sheet metals promises to greatly reduce the production costs by bypassing much of the hot and cold rolling. For higher wheel speeds, such as those used in this investigation, unique material properties may be achieved due to rapid solidification. Figure l(a) shows how the melt is introduced as a free jet onto the wheel in chill block melt spinning (CBMS). In this type of process, the puddle formed on the wheel surface is unconstrained by the crucible nozzle. In CBMS, nozzles with circular cross sections are commonly employed. A major limitation of this process is that ribbons of large width cannot be produced. In addition, the free jet may be disturbed, introducing a flow instability due to the jet breakup and capillary effects. Figure 1(b) shows the method of planar flow melt spinning (PFMS). For PFMS, the small gap between the wheel and crucible is maintained so that the upper surface of the melt puddle is constrained by the nozzle. The flow is introduced from a pressurized crucible with high degrees of control and flow stability due to the small gap. This allows for the production of thinner ribbons with greater width than CBMS. The nozzle geometry commonly used in PFMS is a narrow slit. Planar flow melt spinning is considered to be the most refined form of SRMS, because the flow can be controlled within the small nozzle-wheel gap.
THOMAS J. PRAISNER, formerly Graduate Student, Department of Mechanical Engineering, Temple University, is Graduate Research Assistant, Department of Mechanical Engineering, Lehigh University, Bethlehem, PA 18015. JIM S.-J. CHEN, Associate Professor, is with the Department of Mechanical Engineering, Temple University, Philadelphia, PA 19122. AMPERE A. TSENG, Professor, is with the Department of Mechanical Engineering and Mechanics, Drexel University, Philadelphia, PA 19104. Manuscript submitted September 23, 1994. METALLURGICAL AND MATERIALSTRANSACTIONS B
Both CBMS and PFMS generally employ an enclosed crucible which can be pressurized with an inert gas during the process. The wheel-crucible assembly does not need to be placed in an inert environment, because the exposure time of the molten metal before it is solidified is limited
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