Frozen Layer Ratio result shows the volume percentage of frozen plastic with respect to part thickness at current time step. This value will reach 100% as time passes by.
The picture and the equation below explain how frozen layer ratio is calculated.
Blue: Frozen plastic melt
Yellow: Flowing plastic melt
, where tA is the thickness of the upper frozen layer, tS is the thickness of the lower frozen layer, and l is the thickness of the cavity.
As the melt cools down during the injection processes, the solidification of the melt forms frozen layer near the cavity surface. The increase in the thickness of frozen plastic reduces the cross-section along the flow path and further increases the flow resistance and sprue pressure.
Because solidified plastic has higher resistance to deformation, the thicker the frozen layer is formed, the lower the chance of forming sink marks, but higher the chance of forming voids.