The Visiometa Workflow - Part III: Optimization

by Rene Romeike

Over the course of this series of articles, we show how the use of fast numerical algorithms is revolutionizing the planning of casting processes. Today we will take a closer look at the geometric part optimization workflow.

Unfortunately, even today the design approach for metal components focuses mainly on functional requirements alone. The manufacturing process is only a secondary consideration, at best. However, if the part is to be subsequently produced by metal casting, additional constraints are imposed on its geometrical shape. The most obvious measures are the remedy of undercuts and the addition of draft angles to ensure demoldability. Arising residual stresses can also be an important issue. Yet most overlooked are shrinkage effects resulting from uncontrolled solidification in component areas of varying wall thickness.

The familiar result is the unnecessarily long feedback loop between customers, manufacturers, designers, foundry technicians, mold makers and process engineers. Components that are poorly suited to the casting process can often be produced only after lengthy experimentation phases, involving a great deal of technical effort, or with particularly high scrap rates. To avoid such ramifications, castability must be taken into account in the component design as early as possible, at the latest during the development of the casting system.

One logical solution is to integrate as many individual planning and optimization steps as possible into a single software tool that enables real-time process planning and can be operated by anyone. Visiometa tackles this issue from two directions: By providing intuitive methods for geometric changes, foundry professionals without a CAD background are enabled to try out different design variants in a very short time. Conversely, the uncomplicated and fast modulus calculation also enables component designers without foundry engineering expertise to test their products for castability already during the concept phase.

In just a few minutes, the risk of shrinkage cavities is eliminated by geometric optimization of the component.

Visiometa's sculpting toolkit was developed primarily to answer a specific question: If I take away some material here and put some more material there - how would that affect the likelihood of shrinkage defects? Of course, the part designer could simply make a change in CAD and simulate solidification conventionally. But that would be rather time-consuming, and simulations in larger companies are usually carried out by dedicated specialists, not by the designers themselves. Each change to the cast part naturally entails a new discretization, a restart of the analysis and an extensive data exchange with the simulation engineer. Depending on the necessary number of repetitions, the optimization process can take many weeks that way.

This is where Visiometa's unique workflow really shines. The sculpting toolkit works directly on the discretized 3D model. All changes are thus automatically transferred to the simulation, which provides an updated picture of the solidification process within seconds. If necessary, the foundry technician can also discuss further modification proposals live on screen with the component designer. In this way, product and process development are efficiently tied together as never before.

In the next and last part of the series, we will have a look at the gating and feeding design workflow and how the fast modulus computation saves a vast amount of experimentation and validation time. You can find the previous parts here and here if you are interested and missed them.

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