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Sand Core Modeling Suite: Shooting, Drying & Gas Defect Prediction

Core Shooting - Simulating Sand Cores with the Granular Flow Model

Sand cores are produced by blowing a sand-air mixture into a mold. The foundry engineer's objective is to achieve a homogeneous sand distribution with a sufficient packing of the sand in order to avoid air enclosures in the sand and achieve a good stability of the core. FLOW-3D Cast's modeling capabilities allow the user to obtain the optimum nozzle configuration by varying the number and position of the nozzles through which the sand is blown in and also the number and position of venting nozzles through which the air escapes.

Simulation of sand core blowing process in an intake manifold of an engine; sand distribution in the mold is colored by sand/air mixture density.

Core Drying Capabilities

The core drying model computes the transient drying of moisture remaining in the sand after it has been blown into a core die. Typically, drying is done by blowing hot air through the core while still in the die. Simulating the heating, moisture evaporation and even temporary condensation of moisture in colder parts of the core makes it possible to optimize the drying process. This ensures complete drying while minimizing the energy costs associated with the heating and blowing of the air.

A comparison made by BMW between simulation and experiment of the drying of an inorganic core.

Core Gas Generation and Defects

The core gas model allows users to monitor the progress of resin binder degradation and core gas evolution in sand cores due to heating by the metal. The loss of binder corresponds to the loss of core strength. When monitored together with filling and freezing of the casting, the model is also a predictor of potential gas blows into the molten metal. This potential for gas defects is computed together with core gas flow and core gas pressures and is further discussed in the Casting Defect Prediction section.

Related links:
Modeling Core Gas Generation using the Core Gas model

Case Study: Casting Better Parts by Detecting Porosity with the Core Gas Model

A Continuum Model for High Concentration Granular Media

Modeling Granular Flow: Sand Flow in Hourglass Geometry

 

Binder loss in two internal cores of a valve iron casting

 

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