Mold Flow Analysis Guide for Injection Molding

Mold Flow Analysis (MFA) uses CAE simulation software to predict how molten plastic fills a mold cavity, cools, and solidifies. It is an essential tool for optimizing mold design before steel cutting.

What Mold Flow Analysis Reveals

• Fill pattern & weld line locations
• Air traps & venting requirements
• Injection pressure & clamp tonnage needed
• Cooling time & temperature distribution
• Sink mark & warpage prediction
• Gate location optimization

Common Software

• Moldflow (Autodesk) — industry standard
• Moldex3D — strong for 3D analysis
• SIGMASOFT — virtual molding, no mesh simplification

When MFA Is Essential

• Large parts (automotive bumpers, appliances)
• Cosmetic surfaces with no weld line allowance
• Tight tolerance requirements
• High cavitation molds (8+ cavities)
• New materials without prior experience
• Parts with complex geometry (ribs, bosses, snap fits)

Cost & Lead Time

MFA typically adds 2-5 business days and ¥3,000-15,000 to mold development. The savings from avoided mold modifications (typical rework ¥5,000-50,000 per iteration) far exceed the cost. Many Chinese mold factories include basic MFA in their mold price.