The Density result is generated from a Fill analysis using 3D analysis technology, and shows the density of the tetrahedral elements before shrinkage occurs, at the time the result file was written.
The program measures the density of the material at this time and uses this as the starting point for calculation of the volumetric shrinkage and warpage of the part.
The Density result determines whether the part was uniformly packed with polymer during the packing phase. Variations in polymer density can indicate problems with the part.
Once the material has filled the mold cavity and the packing phase has begun, material flow is driven by the variation of density across the part. If one region of a part is less densely packed than an adjacent region, then polymer will flow into the less dense region until equilibrium is reached. This flow will be affected by the compressibility and thermal expansion of the melt in a similar way to which the flow is affected by these factors in the filling phase.
Accurate simulation of the material flow during the packing phase uses the material's pvT characteristics (density variations with pressure and temperature, compressibility, and thermal expansion data) and material viscosity data.