Do you want to change your Process Parameters for each new Melt?

A quick patent search revealed 87 Rheocasting technologies from the last 30 years. Most of them never left the laboratories that created them. Four technologies are still around. But what’s the difference between them?

GISS, SEED, the SAG method, and RheoMetal. The SAG method, GISS, and SEED work by a temperature-controlled cooling process. Temperature dependency is the critical weakness of these three technologies. If you want a steady process with the same slurry parameters at every shot, the only possibility is to have the melt chemistry fixed. The picture below shows the Al-Si phase diagram—even a tiny change in the silicon level results in a different liquidus temperature. Iron, magnesium, manganese, and strontium also influence the liquidus temperature. This correlation creates a five or more-dimensional phase diagram. When cooling to the same temperature, you will end up at different slurry and casting parameters every time you refill the holding furnace. Then, you have to find the parameters for that exact chemistry. Considering normal variations in chemistry changes at a foundry, these adjustments are not feasible in a series production foundry.

RheoMetal works by melting an aluminium “ice cube”. The ice cube is called EEM (Enthalpy Exchange Mass). It is freshly produced from the same melt as the shot weight. So it has the same chemistry and solidification behavior. You can see that process running in the article about the GTK trial casting. Therefore, typical melt chemistry changes within a foundry do not affect the slurry characteristics. This results in a stable production process with consistent casting quality.

In HPDC, only a casting process that can deliver constant high-quality cast parts throughout the series’ lifetime earns a living for everyone involved. The mentioned production stability of the RheoMetal process provides precisely what foundries need.

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