Resin-Air Two-Phase Flow in Injection Molding Processes: An Application to Polymeric Composite Containing Embedded Metal Wires

Abstract

The development of materials with specific properties is a relevant engineering topic. The composite materials, hybrid of metal structures embedded in polymer matrices, are intensively used in mechanical systems in order to obtain materials with high resistance associated to low weight. To fabricate these materials, it is necessary to inject the polymeric resin in a liquid state in mold cavity, which characterizes a multiphase flow as the air present in the mold is repelled by strategically projected outlets. In this sense, a correct knowledge of the flow mechanisms existing in the molding process is necessary to guide the parts manufacture. Through the Ansys FLUENT® software, this work performs a mathematical modeling of the resin transient flow inside a mold where metal wires are located and presents a numerical solution that describes, through calculations of volumetric fractions, velocity and pressure fields, and the fluid dynamic aspects that characterize the liquid molding process. It has been observed that the pressure required to maintain the constant flow at the mold inlet is increased until 80s of the process, when the steady state condition is achieved, that there is a greater resistance to mold filling in the side regions close to the mold wall due to the metal wires arrangement and that the air removal velocity that occurs due to resin injection becomes very low from the moment that resin reaches the mold outlets.