FIBRE ORIENTATION EFFECTS AT WELD-LINES OF A PA6.6GF35

The dynamics of melt polymer filling the mould cavity in injection molded parts of Short Fibre Reinforced Polymers (SFRP) determines complex fibre orientation patterns, which in turn influence the mechanical properties. The combination of part geometry, number and position of the injection gates determines not only the fibre orientation distribution pattern, but also the formation of weld lines, i.e. surfaces where two or more flow fronts meet. These locations are generally considered weak points, particularly because the resulting fibre orientation distribution is generally affected by discontinuities. The location of the weld lines can be obtained by simulation, using FE software packages like Autodesk Moldflow. The formation of a weld line in a ISO 525 type 1a specimen injected from both ends is shown in Fig.1. However, the assessment of the strength of the weld lines on the basis of these simulations still depends on accurate measurements of Fibre Orientation Distribution (FOD) at these critical locations.