*4.2.2. Triaxial braiding*

the cylindrical form, radial yarns (z-yarns) are linked with other yarns. The thickness of the preform section can be adjusted regarding the end-use. The process requires a machine bed, ±bias and filling ring carriers, a radial braider, a warp creel and a take-up unit. First, shedding mechanism orients the bias yarns at an angle of ±45˚ to each other. Then the carriers wind the circumferential layers by rotating about the adjacent axial yarns. Special carrier units insert the radial yarns and link the circumferential yarn layers with ±bias and axial layers. Then the fabric is removed from the weaving zone by take-up unit. This process results in enhanced

torsional properties for both preform and composite owing to bias yarns.

**Figure 28.** Schematic view of multiaxis 3D circular weaving loom [28, 68].

Two-dimensional braiding is a simple traditional textile based process to make bias fabric. A typical braiding machine consists of a track plate, a spool carrier, a former, and a take-up. The

**4.2. Braiding**

104 Non-woven Fabrics

*4.2.1. Three-dimensional braiding*

A large scale 2D circular triaxial machine was developed by the Boeing Company (Figure 29). The fabric consists of warp (axial) and ±bias fibers. It is possible to cast variously shaped structural elements by using a mandrel [88].

**Figure 29.** Two-dimensional triaxial braiding machine (a) by Boeing Inc. [88] and (b) by Fiber innovation Inc. [89].

Fiber Innovation Inc. developed a large circular 2D triaxial braider machine (Figure 29). The machine consists of a circular bed, an axial guiding tube, a large braider carrier together with formation, mandrel, and take-up units. The braider carrier moves around the axial fiber tubes according to a predetermined path to make ±bias orientation around the axial yarn. Thick structures can be produced by over-braiding on the mandrel. Complex structural parts can be made by cutting/stitching the fabrics [89].
