Why this matters
Know which part risks (weld lines, short shots, sink, warpage) mold flow simulation can actually catch before tooling, and which projects can skip it. Mold flow simulation predicts how molten resin fills a cavity before any steel is cut, catching risks like weld lines on cosmetic surfaces, short shots in thin or long flow paths, and uneven cooling that leads to warpage. It is a real cost and a real time add, so the question is not whether it helps, but whether this specific part's risk level justifies running it.
Buyer checks
Quote variables
| Quote variable | Why it changes the mold route |
|---|---|
| Flow path length and thickness | Long, thin-walled paths raise real short-shot risk that simulation can catch before steel is committed. |
| Cosmetic surface exposure | A weld line predicted to land on a visible face changes gate placement decisions before tooling, not after. |
| Wall thickness variation | Parts with mixed thick and thin sections carry a real warpage risk that flow analysis can flag early. |
| Gate location flexibility | Simulation is most useful when gate location is still an open decision, not already fixed by a prior design. |
Common mistakes
How to apply it
Share the part's wall thickness map and flag which surfaces are cosmetic before asking whether flow analysis is worth running, since that context is what actually determines whether the simulation will change a real decision. If the project is early, the guide can show whether the next move is CAD cleanup, DFM review, prototype tooling, production mold planning, export mold handoff or repair review.