Analysis of Mold Filling in Lost Foam Casting of Aluminum: Part II-Example Applications

Abstract

This paper is the second in a two-part series on mold filling analysis for lost foam casting of aluminum. Part I (published in the IJMC Volume 2, Issue 3, Summer 2008) describes the analysis method, assumptions, and governing equations, and this paper (Part II) discusses applications of the analysis to a variety of pattern shapes that exhibit different types of mold filling behavior, many of which are unique to lost foam casting. The first example compares mold filling in a horizontal foam strip filled from the side with filling in the same strip oriented vertically and filled from the top or bottom. The results illustrate the unusual effect that pattern orientation and thickness have on metal fluidity in lost foam casting. The second example, a rectangular plate filled through a single inlet located on a top, bottom or side edge, illustrates how different modes of foam decomposition can interact during the filling of a single pattern. The mold filling sequence turns out to be dramatically different depending on inlet location and pattern thickness. The third example is a generic box pattern that has long been used at GM and elsewhere to study the lost foam process. This pattern is filled from the back through three separate inlets, creating two merging flow fronts inside the cavity. The likelihood of these metal fronts enclosing foam between them when they come together is explored by examining the concavity of their flow front profiles. For several cases considered in this paper, the results of the analysis are compared with X-ray and neutron radiography images taken during actual mold filling.