Meaning
Injection moulding simulation software models the thermal, rheological and mechanical behaviour of molten polymers throughout the filling, packing and cooling stages of the manufacturing cycle. In tooling engineering and process development, moldflow calculates melt front advancement, clamp tonnage requirements, cooling circuit efficiency and post-moulding part warpage. The software utilises non-linear Navier-Stokes equations coupled with Cross-WLF viscosity models to predict cavity pressure distributions and freeze times.
Its scope covers cavity filling through solid-state thermal cooling, excluding post-demoulding secondary machining operations.
Flow Simulation
Computational solvers discretise part geometry into solid or midplane finite elements to track fluid dynamics during injection. The software models shear-thinning viscosity behaviour, calculating pressure drops across runners, hot drop tips and thin cavity walls. Melt front tracking identifies potential short shots, predicts air trap locations and maps where convergent flow fronts form weld lines.
Processing engineers adjust gate sizes and gate locations inside the software to achieve balanced fill patterns across multi-cavity tools.
Thermal Cooling
Heat transfer algorithms simulate energy exchange between the hot polymer melt, the tool steel and the circulating coolant fluids. Solvers evaluate cooling line placement, baffle efficiency and core pin temperatures to identify hot spots that extend machine cycle times. Non-uniform cooling between cavity and core halves generates asymmetric internal stress profiles, causing predictable part curvature and dimensional twisting.
Modifying cooling channel layouts in simulation prevents warpage before steel mould blocks are cut.
Sourcing Correlation
Material databases inside the simulation environment contain shear viscosity, pvT data, thermal conductivity and specific heat curves for thousands of commercial resin grades. Datasheet values from prime virgin materials yield precise filling predictions, while variable regrind lots introduce viscosity shifts that alter fill balance across production tools. Procurement and processing teams run sensitivity analyses to assess how batch-to-batch melt flow rate variations impact required machine injection pressures.
Validated process simulations compress tool commissioning schedules and reduce physical prototype iterations.
