Mold flow analysis uses computer-aided engineering (CAE) simulation to predict how molten plastic will behave inside an injection mold. By simulating the filling, packing, cooling, and warpage stages, engineers can identify and correct potential issues before steel is cut — saving time, money, and producing higher quality parts.
Fill analysis simulates the injection stage, showing how the melt front advances through the cavity. Key outputs include fill time, weld line locations, air trap positions, and flow front temperature. A balanced flow pattern is essential for consistent part quality. Common issues identified: short shots from inadequate venting, weld lines in structurally critical areas, and overpacking near the gate.
Packing analysis simulates the holding pressure stage after the cavity is filled. This is critical for controlling sink marks, shrinkage, and dimensional consistency. The analysis shows pressure distribution during packing, allowing optimization of pack pressure, pack time, and gate seal timing.
Cooling accounts for 60-70% of total cycle time in injection molding. Cooling analysis simulates the thermal behavior of the mold, identifying hot spots, optimizing cooling channel placement, and predicting cooling time. Well-designed cooling can reduce cycle time by 20-40% while improving dimensional stability.
Warpage is caused by uneven shrinkage during cooling. Warpage analysis predicts final part deformation based on material properties, mold temperature distribution, and fiber orientation. Results help engineers identify the root cause of warpage and adjust gate location, wall thickness, or cooling design to minimize distortion.
Not every mold requires flow analysis, but it is highly recommended for:
Common mold flow analysis software includes Moldflow (Autodesk), Moldex3D, and SIGMASOFT. These tools offer varying levels of detail from simplified 2.5D analysis (midplane or dual-domain) to full 3D simulation. For most injection molding applications, 3D simulation provides the most accurate results, particularly for thick parts, complex geometries, and cooling analysis.