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E. Bociąga, T. Jaruga

Weld line formation in the parts from multicavity injection mold

Polimery 2009, No 9, 654


DOI: dx.doi.org/10.14314/polimery.2009.654

Summary

The results of investigations of weld lines locations in polyacetal moldings, prepared in 16-cavity injection mold with parallel cavities lay-out, were presented (Fig. 1, 3, 4). A method of melt flow visualization was used to record the weld line location on the surface of molding prepared at the proper injection conditions (method of „record grooves effect” formation control) (Fig. 2, 5). Despite using the geometrically balanced runners the cavities were not filled simultaneously (Fig. 6) and asymmetrical flow front of the polymer in the cavities led to weld lines shifts in relation to expected locations (Fig. 8-11). These results were obtained for both small and high injection velocities (Table 1). The reason of the weld line shift is the polymer melt movement in the runners, determined by runners' configuration. The results presented can be used in design of runners' sets in multicavity injection molds allowing preparation of moldings with no deterioration of mechanical strength in weld line area.


Key words: multicavity injection mold, balanced runners, flow lines, weld lines, strength of molding


e-mail: jaruga@kpts.pcz.czest.pl


E. Bociąga, T. Jaruga

Weld line formation in the parts from multicavity injection mold