Porosity Prediction

FLUID FLOW THERMAL & SOLIDIFICATION POROSITY PREDICTION AUTOMATIC MESHING STRESS & DEFORMATION TOOLS PRICING

CAPCAST's porosity module, PORO is the next step in the evolution of solidification analysis software. Used in conjunction with CAP, this porosity module takes data from solidification and makes highly accurate predictions about the location and amount of porosity formed in your casting.

How it Works

PORO was developed based on Dr. K. Kubo (EKK Japan)'s porosity growth model. In his research, he theorized that by making certain assumptions about gas pressure in the material, evaluating pressure drop during solidification, and cooling rates, one could predict where porosity will occur in a casting on a macroscopic leve

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What makes it better than everyone else?

Most other software analysis packages base their porosity prediction on qualitative analysis of the solidification pattern. In plainer terms, when looking at their solidification analysis they note any isolated regions ("hot spots") during solidification. Unfortunately, this method neglects the fact that sometimes porosity can form even when the solidification characteristics of the casting are quite good. Which makes them a lot less accurate then ours.

The following images of an aluminum control arm prove this point:

On the left is the casting solidification pattern. Most analysis codes would be incapable of detecting porosity in this casting because of good "Directional" solidification. There are no isolated regions for shrinkage to occur.

However, PORO tells a different story. The image on the right is a representation of where porosity was likely to occur.

PORO's predictions were backed up by a physical investigation of the actual casting.

Porosity and Shrinkage Detection in Iron Casting

• Generally in aluminum castings, the solidification pattern gives a good indication of where shrinkage porosity will be located. Directional solidification in aluminum castings reduces (or eliminates) porosity.
• Nodular Iron is different. The carbon present in the iron tends to expand during solidification. Even if shrinkage is predicted by looking at the solidification pattern, it tends to be reduced in the real casting because of that expansion.
• Directional solidifcation in iron castings does not always mean quality castings as shrinkage can often occur near gates and risers. This renders general solidification analysis less useful for nodular iron castings.
• PORO goes beyond conventional solidifcation analysis and analyzes how gas pressure, metal pressure, thermal expansion, and cooling rate influence the growth of porosity. It gives a more accurate prediction of porosity in iron castings because it does not rely exclusively on solidification patterns.

CAPCAST highlights the porosity distribution of a casting

Simulation considerations for Fe castings: inoculation effects, water content in greeen sand mold, and mold wall movement.

Thermophysical properties of the green sand mold vary according to water content

Casting volume change is dependent on poition, time, temperature, allow composition, and mold wall movement.

Traditionally, hot spot predictions were used to anticipate shrinkage; however, this technique fails to predict all locations of potential porosity, especially gate porosity. Inoculation is used to reduce such porosity.

Pictured is a casting with no hot spots, shrinkage occurs despite this, and is evident with CAPCAST.

What else does PORO do?

Because of the linear relationships between some solidification characteristics and mechanical properties, PORO can be used to make predictions about the mechanical quality of your castings once they are produced.

Click on one of the images to see a larger picture.

Brittle Hardness................................ Proof Strength

Tensile Strength