Colloque

Mechanical behavior of weldlines in glass fiber reinforced polyamide 66

A. Meddad

B. Fisa

Membre a labase

A. Meddad

Résumé du colloque

Weldlines represent zones of weakness in injection molded parts. In recent publications, weldline strength has usually been studied using tensile tests. In this study, we have investigated the effect of weldlines on the mechanical properties of glass fiber reinforced (10 to 43%) polyamide 66. In addition to tensile tests, flexural and impact behavior has also been evaluated, these two latter methods being more closely related to in-use performance of molded parts. A rectangular mold (2, 4, or 6mm deep) with a circular insert was used to make samples with the weldlines. The fiber orientation in the weldline zone, which is several millimeters wide, is parallel to flow throughout the entire thickness; away from the weldline, the core thickness where the fiber orientation is perpendicular to flow is only about 25% of the thickness. The flexural strength loss due to the weldline is of the same magnitude as the tensile tests (30 and 50% for the 2 and 4mm plaque - 33% G.F.). The impact results on falling weight test on circular samples show the change of fracture mode due to the weldline can actually lead to an increase of the energy absorbed by the plaque during rupture.