Abstract
The effect of gravity on free surface shape during the filling of a disk-shaped cavity is experimentally studied. A disk-shaped mold cavity is constructed to measure spreading of the fluid front due to gravity. Fluid front sensors are mounted on the top and bottom mold walls at three radial locations. The time the fluid front reaches these sensor locations is recorded. This data is used to calculate the radial distance between the top and bottom of the fluid front at each sensor location. The important parameters that govern the fluid front dynamics are identified as the Reynolds, Bond, and Capillary numbers. Spreading is found to be mainly dependent on the Bond number, such that a large change in spreading is observed due to a small change in Bond number. Spreading increases with decreasing Capillary number and remains nearly constant over the range of Reynolds numbers studied.
Highlights
MOLDING OPERATIONS INVOLVING polymers, e.g., Reaction Injection Molding (RIM), are commonly used to manufacture net-shape components quickly and inexpensively
A number of experimental and theoretical studies on free surface shapes are published in literature
In Behrens et al [1] the fluid front shape is completely dictated by the flow kinematics and gravity effects are
Summary
MOLDING OPERATIONS INVOLVING polymers, e.g., Reaction Injection Molding (RIM), are commonly used to manufacture net-shape components quickly and inexpensively. Molding is usually characterized by the displacement of air in a cavity by a polymeric resin which is either cooled or cured to form the final solid part. The interface between the polymer and the air, referred to as the free surface, progresses through the cavity. It is commonly known that the dynamics of this free surface can affect heat transfer as well as curing rate in the mold, and the mechanical properties of the molded part. A number of experimental and theoretical studies on free surface shapes are published in literature. The most common approach in determining free surface shapes in molding processes is to assume the Capillary number is high and that viscous forces dominate surface forces. In Behrens et al [1] the fluid front shape is completely dictated by the flow kinematics and gravity effects are Journal of COMPOSITE MATERIALS, Vol 35, No 14/2001
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