The Rapid S process is a semi-solid casting process, meaning:

1. The melt is partly solidified into
a consistency of small round
grains surrounded by melt.

2: This structure is created by a rapid undercooling in combination with the shearing of the melt.

3: The Rapid S slurry becomes thixotropic. The shear force required
to deform a thixotropic slurry is very low, resulting in a more accurate filling of the mold.

4: A semi-solid slurry is usually
100 degrees C cooler than
a traditional melt.
Its thixotropic behaviour results in
a laminar metal flow, which reduces gas and shrinkage porosity.