Braided Fibers - Manufacturing, Benefits and Applications

Interview conducted by G.P. ThomasApr 10 2013

Topics Covered

What are Braided Fibers?
How are Braided Fibers Manufactured?
Companies Involved in Braided Fiber Manufacturing
Benefits of Braided Fibers
Applications
References

What are Braided Fibers?

Braiding consists of three or more yarns mechanically intertwined in such a manner that no two yarns are twisted around one another. The braids are continuous, which enables the load to be evenly distributed throughout the structure. These fibers are coiled into a helix, similar to wire in a spring.

Tubular braid features continuous seamless fibers from end to end of a part. The braided fibers are manufactured in the form of sleeves, wide fabrics or flat tapes. The sleeves have the 'Chinese finger-trap'-effect so that it conforms to the shape it is reinforcing.

How are Braided Fibers Manufactured?

Braid can be easily and commonly manufactured. It is used as a freestanding fabric with a stable braid angle for a given diameter.

The construction of the biaxial braid is in the form of a basket weave with two yarns crossing over and under each other. The biaxial braid sleeve is pulled over a mandrel that has changing cross-sections. The fiber orientation, thickness, and yield of the braid differ at each point along the mandrel, which is useful for certain applications.

Any fiber possessing certain amount of flexibility and surface lubricity can be easily and cost-effectively braided. The most commonly braided fibers include carbon, ceramics, aramid, fibreglass, and several natural and synthetic fibers and thermoplastics.

Using various raw materials for yarn, a hybrid braid can also be created to meet specific requirements, optimize the reinforcement costs, to form aesthetically pleasing patterns within the fabric that already has beautiful symmetry.

It is possible to manufacture braids in numerous diameters or widths, fiber angles and areal weights.

Companies Involved in Braided Fiber Manufacturing

• ADL Insulflex Inc., a member of The ADL Group, is located in Ontario, Canada. They manufacture the braided fiber material called Thermosleeve™ S. It is manufactured from smooth glass fiber yarn and braided at high yield angles so as to allow about 25% expansion and contraction. Thermosleeve™ S is an expandable heavy wall braided glass fiber sleeve that is designed to operate at a continuous temperature of 538°C (1000°F). The smooth fiber yarn is heat cleaned and coated with an acrylic saturant to remove loose fibers, improve handling characteristics, and develop better abrasion resistance. Although the acrylic saturant starts to decompose around 204°C (400°F), it has no effect on the thermal operation of the sleeve. The expandability of the Thermosleeve™ S creates a custom size range.
• DragonPlate is a part of Allred and Associates Inc., an engineering product development and manufacturing company located in Elbridge, New York. DragonPlate products are designed for use in constructing high performance structures. One of their products is the braided carbon fiber tube, which combines carbon fiber braid and unidirectional fabrics. This tube is designed to withstand torsional and side loading and is lighter than pultruded tubing. The unidirectional braids help to prevent longitudinal cracking and splitting. The braided carbon fiber tube has a unique wet shiny appearance.
• A&P Technology is one of the leading producer of precision braided composites in the world. They own braiding machinery such as Megabraiders™, which is considered to be the largest braiding machinery in existence. This machinery enables the company to cater to the composite designers' needs for braided reinforcements of large diameters with small unit cells.

Benefits of Braided Fibers

The following are the key benefits of braided fibers:

• Generally, when a structure is exposed to elevated fatigue cycles, micro-cracks tend to occur through the matrix of unidirectional prepreg laid-up structures. The micro-cracking can, however, be stopped at the intersections of the reinforcing yarns, thus enabling this material to be easily adapted for use in the aerospace industry.
• The efficient distribution of load in a braided structure enhances its impact resistance.
• Braids improve interlaminar shear properties when combined together with other braids. Interlaminar adhesion in braided structures enables the layers to move together, which helps to prevent cracks.
• As braids are woven on a bias, they provide very efficient reinforcement for parts that are subjected to torsional loads.
• Braids can be easily and repeatedly expanded to fit over molding tools or cores. They can accommodate straight, uniform cross-section forms as well as non-linear, irregular cross-section components.
• Braids can be designed with high level of flame resistance, abrasion resistance, flexibility and expandability.

Applications

Braids are used in many industrial applications. Some of the common applications are listed below:

• As fan blade containment in commercial aircrafts
• For energy-absorbing crash structures in Formula One racing cars
• As reinforcement for aircraft propellers and stator vanes in jet engines
• For building light weight frames and structures such as trusses
• For use in precise manufacture of composite parts
• Ideal reinforcement for drive shafts and torque transfer components, such as flanged hubs
• For products with changing geometries like prosthetics and hockey sticks.

References

• Braid Basics-Braider
• Braided Fibers-ASMInternational
• Thermosleeve™ S-Adlinsulflex
• Braided Carbon Fiber Tube-Dragonplate