During one of our overbraiding presentations at a conference interest was triggered for Scheldebouw to handle the current manual preform manufacturing .

Scheldebouw had the order to deliver the unique facade elements for Maison du Livre in Luxembourg.

 

In a previous work “Stadskantoor Utrecht” the construction was made of lightweight foam cores, which were wrapped by woven roving mats.
This generally results in a rather bulky preform, which can have a different infusion resistant for the resin an affect the endpart.

The new Technology

The ‘new’ technology is preforming by overbraiding, which we are doing since 1994.

Instead of creating a wide woven fabric first, cut out sections and placing these pieces manually on the foamcore. The foam core is moved through the braiding machine. The machine below has 144 braiding carriers for the biaxial fibers ( ±45º) and a UD creel with 72 positions for the Uni Directional fibers.

During the overbraiding the fibers are placed in 3 directions within one single layer.

The bias fibers which can be  ±45º oriented will take up the torsion loads in the component. The UD or 0º fibers will handle the bending loads.

Now there is the possibility to vary the fiber amount at each of the 72 UD positions.
For the beam to handle more bending loads in one particular direction, more UD fibers in this preform region is inserted.

At the top the ratio between biaxial fibers and UD fibers is 22/78%. At the sides this is 59/41%

Several geometries were overbraided with multiple layers to get to the required thickness.