Braided composites are a common construction material for high-performance, lightweight components of modern aircraft and cars. They consist of multiple strands of glass or carbon fibers braided into a tubular structure. Although specific braiding machines vary, the general process of producing braided composite is as follows;
- The first step in braiding is to engage the warp (cross) thread into each of the holes in the adjacent carriers and tighten them down, so there is no gap between them. At this point, operators must ensure that all loose ends of all rovings are either taped or tied off since they cannot be cut until after braiding has been completed.
- The next step involves positioning each bobbin carrier in its desired position along the machine’s P-frames. Here, small pieces of fiberglass called pick tapes are used to guide fibers through the braiding process. Tape is used because it will not leave residue on the finished composite, whereas cloth, paper, or plastic are not suitable for this purpose due to their ability to shed fibers.
- The next step involves threading all free ends of rovings back onto bobbins to exit behind where they entered. When performing this process, it is important to ensure that each roving remains in its designated spot and does not overlap with neighboring rovings. This can be done using either a weaver’s knot or a simple overhand knot.
- Once all the bobbins have been reloaded, the machine is ready to start braiding. The operator begins by activating the cross-threading mechanism, which pulls each warp thread into position and secures it against the adjacent carrier. This process is repeated until all of the carriers are engaged.
- The machine then rotates, drawing fiber from each bobbin in a specific pattern to create the desired braid. The speed at which the machine rotates will determine how thick or thin the finished composite will be. As the braid progresses, new rovings are added, and the twill pattern becomes more pronounced.
- Once braiding is complete, all excess fiber ends must be trimmed, and any defects in the weave must be repaired. This can be done by hand using a sharp knife or scissors or a special trimming machine. After trimming, the Braided Composites are ready for finishing.
Producing a braided composite is an effective way of reducing costs while still providing good protection. The use of the composite can lead to a reduction in weight and an increase in stiffness, which are both important factors in many aerospace applications.