Abstract
Epoxy resins are one of the most widely used thermosetting materials, especially for transformer insulation in the electrical industry. One of the primary technologies used for manufacturing such products is based on pressure casting. Computational fluid dynamics (CFD) calculations of the mould filling stage in a pressure casting process for epoxy resin casting are carried out and presented in this paper. Two designs of a gating system are studied and their effects on the flow parameters in the mould are analyzed. The two designs being top pour and bottom pour inlet. A new solver is developed in an open source CFD framework, OpenFOAM, which incorporates the Navier–Stokes equations, energy equation including the viscous dissipation and a new isoAdvector approach for capturing the liquid-gas interface. The objective is to simulate the flow and heat transfer of epoxy resin, while being filled in the mould that is initially empty and heated to a specified temperature. Formulation was validated with experimental measurements of the classical dam breaking problem. For the resin filling problem, further verification was carried out using grid-dependent studies and temporal fill factor comparisons to experiments. In addition, instantaneous contours of volume fraction and temperature, and velocity vectors are studied to understand the flow patterns and heat transfer in the mould during the filling process. Among both the gating designs, the bottom pour was the more preferred one as it resulted in less turbulence, sloshing and it provides an easy passage for the voids to escape leading to higher fill factor. This analysis also helps in recognising the location of voids and thereby help in potentially identifying optimal process parameter settings for a more suitable mould design.
Published Version
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