Abstract: This review covered the following four aspects: pressure-volume-temperature(PVT) relationship of polymer materials, the core principle in precision injection molding, polymer PVT tester, the online diagnosis and self-healing control of defects in the injection molding. The opplication of PVT relationship was introduced.

Key words: Polymer material, PVT property, Precision injection molding, injection molding defects online diagnosis and self-healing control