afs.gif (3195 bytes)

amc.gif (6172 bytes) sfsa_s.gif (4934 bytes)
A Design Study in Aluminum Castings - GM Cylinder Block                                          
Foam Pattern Decomposition

As the metal is poured into the mold,  the heat of the advancing melt front progressively collapses, melts, depolymerizes, and vaporizes the polystyrene foam.

Collapse --  100C / 212 F            >>>     Melt -- 165C / 330 F    >>>
Depolymerize -- 315C / 600F    >>>    Vaporize -- 576C / 1069F
Movie of Metal Flow into Low Fusion Foam Movie of Metal Flow into Full Fusion Foam

The density and fusion condition of the foam affect how the foam decomposes. 
---
If the foam is underfused, it will decompose non-uniformly and metal flow into the mold will be fast and turbulent, trapping residue and causing fold defects and pores. 
--- Fully fused foam will decompose evenly and produce smooth, uniform metal flow with no defects or trapped residuals.

Flaw-free castings require controlled metal flow and consistent foam density and bead fusion.


Back


Next

26

 

afs.gif (3195 bytes)
Return to AFS
Home Page

Copyright 2004 by the American Foundry
Society  All rights reserved.
 
Address comments to:  jss@afsinc.org
Last Modified:August, 2004 by STG

arrow_top.gif (1191 bytes)
Page 1

In cooperation with
GM Powertrain Casting Development