Abstract: advances in predicting, optimizing, and controlling the location of weld-lines in injection-molded parts were reviewed.The mathematical model of weld-lines’formation in filling process was introduced. The analysis flow, predicting method and practical examples of the technologies such as numerical simulation, simulation combined with the theory of mathematics programming, valve- injection and the control technique of multi spruc feeding sequence for large injection parts wereintroduced in detail. Such simulation technology based on a combination of theory and mathematics programming had become a focus of research with increasing applications. Valve-injection and thecontrol technique of multi spruc feeding sequence for large injection parts can be successfully implemented to avoid weld-lines, and have wide application prospect in industrial practice.

Key words: injection-molded part, weld-line location, predicting, optimizing, controlling