Solidification Time shows the time, in minutes, for each part of the casting to become COMPLETELY solid, i.e., to cool to the Solidus Point.
Viewing a plot of Solidification Time shows the progress of solidification through the casting. This can help to locate isolated areas of molten metal within the casting and to get a general idea of progressive solidification in various areas of the casting.
For most alloys, you are looking for a good progression of solidification, from the edges of the casting, out through the riser contacts and into the risers. If any area becomes isolated, it is an area that will be prone to shrinkage.