Net Shape Stacking and Consolidation of Thermoplastic Composite Tapes

Abstract

Thermoplastic composite tapes are produced with a specific width, e.g. 300 or 600 mm. A common production method is first to slice the tape rolls into narrow tapes bands with a width of e.g. 50 mm. These narrow tapes are used for stacking operations. Upon using such a technology, it is necessary to combine several narrow tapes to end up with a single layer. The outer edges of the tape stack normally extrude beyond of the area needed for the part, meaning, a cutting operation is necessary, either right after the stacking or after the consolidation. A beneficial alternative approach starts with large cutouts from the rolls, which are obtained by efficient stamping. These cutouts cover as much area as possible in one piece. The idea is to use the full tape width, if possible. The cutouts are stored in automatized magazines and become stacked efficiently employing a pick-&-place approach. The use of image processing enables precise adjustment of the gaps and overlaps.

This net-shape stacking technology leads to stacks that consist of a minimum number of tape cutouts. Even different types of tapes can be combined. The net-shape stacking is followed by an also net-shape consolidation in a heating-&-cooling unit. Both, the stacking unit as well as the consolidation unit are capable producing stacks and blanks within a typical injection moulding cycle time of one minute. The consolidated blanks fulfil the requirement of a best fit outer contour, which can be draped into the desired shape of the final part. Furthermore, the tailored composite blanks may expose the distinct variations in thickness and fibre orientation, which is optimized for the final part’s specific loading conditions.