Meaning
Solid particulate statistics quantify the collective range of grain dimensions present within a bulk sample. Particle size distribution categorizes grains by their volume or diameter to map the frequency of different dimensions across a given population. This statistical profile dictates how powders behave during fluidization, packing, and melt rheology.
Rheology Impact
Resin manufacturers control these grain dimensions to ensure uniform melting rates within extruder barrels. Particle size distribution influences the bulk density of pellets or powders entering the feed throat of an injection moulding machine. A narrow spread of grain dimensions facilitates predictable flow, whereas a wide spread leads to uneven heating and inconsistent viscosity.
Inconsistent grain sizes often trigger voids or structural weakness in the final moulded part.
Regrind Economics
Regrind operations frequently encounter shifts in grain population due to the secondary grinding process. These variations in particle size distribution alter the packing density of the material inside the hopper, which changes the volume of resin delivered to the screw per rotation. Virgin resins follow strict specifications to minimize these fluctuations, while regrind batches necessitate frequent machine recalibration to maintain consistent pressure profiles.
Measurement Standard
Laser diffraction serves as the primary analytical tool for defining these material parameters across industry laboratories. The equipment maps the scattering pattern of light as it passes through a suspension of particles. This method provides the mathematical foundation for comparing feedstock consistency between different suppliers and batches.
The accuracy of the resulting model relies entirely on the successful dispersion of the material in the measurement medium.
