The Cured layer fraction result shows the fraction of thickness where the degree of cure is higher than the gelation conversion.
The gelation conversion indicates the onset of gelation, where the material viscosity reaches an infinite value in a Reactive Molding analysis.
The Cured layer fraction result is generated from a Midplane and Dual Domain Reactive Molding and Microchip Encapsulation analysis.
The value of cured-layer fraction can range from 0-1 to indicate the thickness fraction of the cured layer. A higher value indicates a thicker cured layer (or thinner flow channel) and higher flow resistance. During fill, the cured layer in the areas with flow does not increase as rapidly as in the areas where flow has already stopped. This is because the heat transfer from the mold wall is balanced with the cold resin coming from up-stream. Once the flow stops, the heat transfer from the mold wall and the heat released by the reaction completely dominate the area. A rapid increase in the thickness of the cured layer can be seen.
Cured-layer thickness has a significant effect on flow resistance because the thickness of the flow channel is reduced as thickness of the cured layer increases. The effect of the thickness reduction can be roughly estimated by the definition of fluidity. Fluidity is proportional to the cubic power of part thickness.
A fifty percent reduction in thickness reduces fluidity by a factor of eight (or increases the flow resistance by a factor of eight). In fact, this factor becomes sixteen in the case of runners.