The 4th generation "Spiral Taping" technology that we use first in Europe derives from "Filament Winding", developed in Germany a few years ago and has totally changed the way of producing composites in tubular structures such as the rims of a bicycle.
The "Spiral Taping" was developed for the Aerospace sector; it is used, for example, to produce warplane parts such as the Lockheed Martin F22 Raptor (air intake of the engine) or the turbofan blades of the General Electric GEnX engines or the carbon nacelle of the new Boeing 787 DreamLiner (see photo).
Unlike the classic lamination of composite rims, the "Spiral Taping" technique is performed by a Cobot (Collaborative Robot), programmed to wind (under constant and controlled tension) the carbon fibers with an orientation defined by the efforts predicted at FEA during the design.
Differences between Spiral Taping, Filament Winding, and traditional lamination
In "Spiral Taping" the carbon fibers are perfectly spread out and do not have the typical "crimp" assumed by the fiber during the braiding process used in "Filament Winding". This gives the composite very high mechanical characteristics and a higher weight/strength ratio than any other lamination method. Contrary to the classic " Filament Winding ", the absence of the "crimp" of the carbon fibers in the "spiral taping" makes them work homogeneously in the stress areas together with the resinous matrix.
This technology brings several advantages compared to any traditional technique (albeit highly advanced) and also compared to filament winding, because it overcomes the insurmountable limits of both technologies:
- Absence of any interruption of the fibers along the rim circumference. With the traditional technique, strips of UD carbon with alternating inclination are manually deposited in the mold, to form the walls and the rim channel. Each layer must necessarily have an interruption to make room for the next layer with opposite inclination of the fibers. In "Spiral Taping" there is only a beginning and an end of winding of the UD fibers throughout the rim, therefore there are no clear joints either inside the composite or on the surface, always present and inevitable in any traditionally laminated rim (see photo).
- With the "Spiral Taping" any joint in the bead of the rim, unavoidable with any traditional technique, is eliminated. The layers of carbon that make up the walls of the rim and those of the rim channel are interrupted in the bead area. This in an MTB rim makes the weakest point of the composite prone to breakage. With "Spiral Taping" technology, the carbon fibers that make up the rim are continuous over all 360 degrees of the section perimeter, significantly increasing the strength of the composite in this area.
- In "Spiral taping" the pre-preg UD continuous fibers entering the composite are kept under tension, therefore perfectly spread out. This is impossible to achieve in traditional hand lamination techniques. Not only is a very high constancy of behavior obtained, but the resistance increases with the same thickness, because all the fibers are incorporated into the resinous matrix at the same tension and therefore will work in unison under stress.
- Classical lamination is replaced by a programmed machine with many process controls. The "Spiral taping" ensures very high and precise repeatability for each rim produced, reducing waste and guaranteeing exceptional quality. Finally it goes through an X-ray machine for inspection. Our Athmos™ rim series uses a tri-cross pattern on the nipple hole for strength and stiffness.
- Absence of human intervention in the lamination of the composite, maximum repeatability. Human intervention is limited to the insertion of the newly formed circle into the mold for the subsequent curing phases of the resin, the only phase remaining the same as traditional lamination.
- All the numbers of the composite (heel resistance, lateral flexibility, wall breakage, nipple tear) are clearly superior to the traditional lamination technique.
Disadvantages of "Spiral Taping" technology:
- Considerable investment costs in hardware (Robot System), software and specific know-how, keeping the standard ones fixed.
There will certainly be an extension of this technology in the cycle sector; The RaceFactory™ Team is happy to be among the very first to introduce what in a few years will become the standard technology for producing composite rims.
Innovation, not Imitation™