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Predicting Core Gas Defects with FLOW-3D Cast

Modeling Castings with Cores

Chemical binders in the sand can produce gas when heated by the molten metal and if not vented adequately, the gas may flow into the metal resulting in a gas porosity defect. This is most likely with cores that form thin interior features of castings that heat up quickly and have long venting paths. The core gas model in FLOW-3D Cast predicts the possibility of such gas defects and helps design core venting that can safely evacuate all the binder product gas from the cores.

Core gas simulation predicts casting defects using FLOW-3D Cast.
Figure 1: Spatial plot of core gas pressure and core gas surface flow to metal at 5 sec. A two internal core assembly was bottom filled in the simulation in 1.5 sec. The gas pressure in the saddle core is roughly double what it is in the T-core. The vertical drill in the T-core along with one T-core print is very effective in venting all the T-core binder gas. The saddle remains inadequately vented in this design.


Related links:
Predicting Defects with the Core Gas model

Casting Better Parts by Detecting Porosity with FLOW-3D Cast's Core Gas Model

Modeling Defects in Aluminum and Iron Castings

The Core Gas model predicts defects for resin-bonded cores both in iron castings (Fig. 1) and in aluminum castings (Fig. 2). It works concurrently with filling and solidification models in FLOW-3D Cast and computes binder gas generation and flow during and after the end of casting fill.

Flow simulation: Filling of an open flask partial V8 Al block assembly.Flow simulation: Filling of an open flask partial V8 Al block  assembly.
Figures 2a and 2b: Filling of an open flask partial V8 Al block assembly. The two cores form the water jacket cavity of the block. The flask is bottom filled with Al in 20 seconds (Fig. 2a) and the water jacket core when unvented blows gas into the metal during fill (Fig. 2b).