Defect Prediction

A major challenge when designing a casting is determining whether or not the final part has defects. Designers can often produce a good quality part by following best-practices for designing gating, runners, risers, pour temperatures and chill sizing. However, in today’s business environment, good may not be good enough to beat the competition. With FLOW-3D CAST‘s powerful defect prediction tools, casting designers can quickly and accurately identify and locate defects allowing parts to be produced with higher quality in a shorter amount of time.

Air Entrapment

The air entrapment model in FLOW-3D CAST is used to estimate the amount of entrained air that occurs in metal casting systems during filling. This model is based on simple physical mechanisms and is an excellent predictor or porosity. Using this model, casters can use simulation to prevent air entrapment defects and eliminate the trial and error process. Visit the modeling capabilities section for more information about the Air Entrapment Model.

Air entrapment defect prediction
FLOW-3D Cast accurately predicts defects due to air entrapment

Core Gas Defects

FLOW-3D CAST‘s 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 so that they can eliminate core gas defects in their castings. 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. Learn more about this model >

Core gas defects
Binder loss in two internal cores of a valve iron casting

Die Erosion Defects

FLOW-3D CAST accurately predicts die erosion defects due to cavitation during filling in high pressure die casting. Metal pressure can drop several atmospheres below the metal vapor pressure in areas of very fast flow, possibly causing cavitation and erosion. A simple way to predict damage due to cavitation is to predict the likelihood of the cavitation, or the cavitation potential, without actually introducing cavitating bubbles into the flow. FLOW-3D CAST evaluates the cavitation potential by looking at the difference between the cavitation pressure and the local fluid pressure. The potential for cavitation and die erosion at the cell’s location is deemed to exist when this difference is large. The most reliable indications of possible die erosion are highly-localized “hot spots” — small areas with high values of this quantity.

Die erosion defects

Microporosity

FLOW-3D CAST has a model specially designed to predict the occurrence and location of microporosity defects occurring late in the solidification stage. With this information, you can make design adjustments and avoid critical defects. Cast metal parts are sometimes unusable because they have large internal gas pockets, or porosity, that develops when the metal shrinks during solidification. Most large-scale porosity can be eliminated by a careful design of the casting mold to keep extra liquid metal in special regions for feeding the shrinkage. When metal can flow to compensate for shrinkage, porosity usually does not occur. Another type of porosity is referred to as micro-porosity because it usually appears as a distribution of small bubbles whose total volume fraction is typically on the order of 1% or less. Having a means of predicting the location and magnitude of micro-porosity is therefore of considerable interest. FLOW-3D CAST‘s microporosity model has been developed for this purpose.

Microporosity casting defects flow3d cast

Solidification & Shrinkage

FLOW-3D CAST has a complete suite of tools for modeling solidification and pinpointing areas of excessive shrinkage or porosity, allowing you to determine placement of risers to assure such defects are alleviated. There are a wide range of defects associated with solidification, including segregation, thermally-induced stresses, and micro and macro porosity. An important first step to obtaining correct solidification analysis is accurate filling. An accurate fill captures the correct thermal profile, which is an initial condition for solidification modeling. FLOW-3D CAST can detect many solidification-related defects enabling foundries to design casting parts more quickly and reduce scrap rate.

Microporosity casting defects

Surface Oxides

FLOW-3D CAST‘s defect tracking capabilities help casting engineers predict where surface oxide defects are most likely to occur from the filling process. Oxides form due to an exposed molten metal surface to air and can end up in the part in undesirable locations. The final location of the defects depends on the overall flow conditions, turbulent mixing, fluid jetting and impingement. FLOW-3D CAST accurately tracks these oxides and their final locations to help improve designs.

Surface oxide defects

Thermal Stress Defect Prediction

FLOW-3D CAST’s thermal stress model enables you to predict precisely where thermal stress defects will occur and how a casting distorts. Stresses are simultaneously computed in the mold and in solidifying metal with simple options for the interaction between them. Learn more about simulating thermal stress evolution in the modeling capabilities section so that you can start eliminating thermal stress defects in your metal castings.

Thermal stress defects