Carbon fiber raises consumer performance index
Carbon bridges gap between large-volume sporting goods and aerospace to satisfy discriminating tastes in consumer and professional markets.
By Dale Brosius, Contributing Writer | January 2005
The development of composite materials opened the door for designers and engineers to create new shapes and achieve uncommon levels of performance. As a replacement for metals, composites have lightened aircraft and automobiles and improved the game of many a golfer and tennis player. Although glass fiber reinforcements got things rolling, it was the invention and application of carbon fiber in composites that provided the real opportunity to make significant advancements in these applications.
In the wake of such success, product manufacturers in other arenas have followed suit. Although not produced in the mass quantities typical of composite sporting goods, products positioned at the crossover point between consumer and professional quality in these markets now take advantage of carbon composites as substitutes not only for metal but wood as well, with remarkable results. In all cases where carbon has found a place, there runs a common theme: Carbon fiber improves performance, and in each market, there are plenty of people willing a pay a premium for that performance edge -- not to mention the carbon-inspired high-tech styling.
Music to the ears -- and more
Since the invention of the compact disc, the music industry has trumpeted the advantages of digital music. "Analog is history," the refrain went. In recent years, more and more audiophiles are rediscovering vinyl and tape, and the subtleties digital music can never duplicate. To appreciate these differences, higher quality equipment is required to play and broadcast it, and this is most significant in the choice of speakers.
Source: Wilson Benesch
Although it is finished on its forward side with a wood veneer and capped with a solid-wood top, the structural cabinet of this A.C.T. audio speaker is a single-piece, U-shaped, carbon-fiber composite, produced by resin transfer molding (RTM). Extra stiffness is obtained via the use of a co-molded structural foam core.
Carbon fiber has found application in the cones of many high-performance speakers, either as a paper or light woven fabric. But Wilson Benesch Ltd. (Sheffield, U.K.) has taken carbon fiber to an entirely new level. Founded in 1989, the company's first products included a carbon-fiber turntable and a torsionally stiff carbon-fiber tonearm. Building on this technical success, Wilson Benesch introduced the first of its line of speakers in 1994, relying on carbon fiber's structural properties in the external housing of the speaker to provide improved damping and sound quality, giving buyers a purer listening experience. Distinguished by a curved two-piece cabinet featuring high-gloss, woven structural carbon fiber composite, the A.C.T. One (A.C.T. stands for Advanced Composite Technology) struck a note with music purists worldwide and was selected as the reference loudspeaker by a number of audio equipment reviewers. The A.C.T One was followed in 1997 by the slightly larger A.C.T. Two and several other speaker models, all incorporating carbon fiber in the structural cabinet. In 2002, Wilson Benesch developed an all-new speaker, named simply the A.C.T., to replace the One and the Two. The A.C.T. incorporates significant advancements in its construction.
Standing 1080 mm (42.5 inches) tall and weighing 78 kg (172 lb), the A.C.T relies on a lightweight composite and a heavy metallic structure to achieve the proper balance of strength and performance, explains Wilson Benesch director Andrew Scholey. Within the carbon composite housing, a rigid, welded steel backbone and hybrid steel/aluminum baffle rigidly support the speaker cones to minimize vibration. "The stiffness and damping characteristics of carbon fiber composite provides a low degree of 'colorization,' or the vibration typically seen with a wood-based speaker housing," Scholey emphasizes. The result is a cleaner replication of the musical performance.
While earlier speaker models relied on autoclaved sandwich structures of carbon fiber prepreg and Nomex honeycomb, the one-piece U-shaped monocoque housing for the A.C.T. is resin transfer molded, Scholey says, noting, "From our inception, we have produced the majority of our parts ourselves, and in so doing, have complete control over the quality." The A.C.T. housing is comprised of a 15-mm/0.59-inch-thick foam core encased by 2x2 twill woven fabric skins infused with epoxy resin. A skin thickness of 2.5 mm (0.100 inch) yields a sandwich structure with exceptional stiffness-to-weight characteristics.
The suggested retail price for a pair of A.C.T. speakers is $12,500 (USD), a relative bargain for speakers with these specifications. Scholey estimates the market for high-end speakers, which includes the A.C.T. and other Wilson Benesch models, is in the tens of thousands of units per year.
Lightweight tripods gain acceptance
A key element in obtaining a quality photograph is maintaining the stability of the camera. Trying to capture a long exposure simply through a steady hand is not sufficient -- some sort of stabilizing device, such as a tripod, is required. Backpackers, nature photographers and sports journalists rely on collapsible tripods to capture the action or the beauty of the outdoors. Frequent relocations and difficult to access locations make having the lightest gear not only handy, but essential. Durability is another factor in buying equipment, and carbon fiber composite tripods are both lightweight and durable.
Source: Vitec Group
Carbon fiber legs of this rugged Gitzo camera tripod save precious weight yet provide excellent stability for nature, wildlife and sports photographers. The legs are produced using the pull winding process.
Gitzo SA (Creteil, France) pioneered carbon fiber camera tripods in the mid-1990s, with Gruppo Manfrotto Srl (Bassano del Grappa, Italy) not far behind. Today, the two companies, which are both owned by Surrey, U.K.-based Vitec Group PLC, are the leading producers in this rapidly growing market. Both offer a wide range of carbon fiber tripods to satisfy various customers, ranging from performance-seeking amateurs to ultimate professionals. Retail prices range from around $250 to $800 (USD) depending on tripod size and features.
Justin Stailey, technical support engineer for Bogen Imaging Inc. (Ramsey, N.J.), explains that the market for carbon fiber tripods falls into several categories, including nature photographers, sports photographers, and local news video cameramen on the professional side, and affluent hobbyists, such as birdwatchers, on the consumer side. Bogen is the distribution arm of Vitec, supporting Gitzo and Manfrotto products in the U.S., France, Italy and Germany. Stailey says a typical carbon fiber tripod weighs 30 percent less than an all-aluminum equivalent, and newer models that combine carbon legs with magnesium (rather than aluminum) heads and fittings can weigh as much as 40 percent less. In a large tripod, this can mean a difference as great as 2.0 kg/4.4 lb, lightening the load or permitting the photographer to carry a longer lens or other equipment.
Although Gitzo and Manfrotto fall under the same management, their tripod products are differentiated by certain features, most significantly, the shape of the telescoping carbon-fiber legs. Gitzo legs are circular, and have a smooth, sanded appearance, while the Manfrotto legs have a textured surface and are formed in a trapezoidal, or "D" shape to resist twisting in the fittings. The Gitzo tubes have a 1.5 mm (0.060 inch) wall thickness, with upper leg diameters ranging from 22 mm to 41 mm (0.875 inch to 1.625 inch), depending on tripod size. Since Gitzo was the first producer of carbon tripods, the 1.5 mm wall was selected to fit existing aluminum hardware, which was sized for 1.5 mm aluminum tubing. By comparison, Manfrotto tubes have only a 1.2 mm (0.048 inch) wall thickness, and future Gitzo models are adopting the same thickness to further reduce weight, says Stailey.
Carbon fiber tubing for both product lines is produced by a process called pull winding, a hybrid pultrusion/filament winding technique in which longitudinal fibers are pulled over a round or trapezoidal mandrel that extends back to near the creel. As the fibers pass through the winding station, off-axis fibers are wound, with tension, around the zero-degree fibers, which compacts the dry bundle. The combined "continuous preform" enters a heated, tapered die (containing an inner mandrel and an outer mold that defines part thickness), where the resin is injected into the part in a continuous fashion under a fairly high pressure. As in conventional pultrusion, the part cures as it is pulled through the die, and tubes are cut to length by a flying saw.
Stailey estimates the current worldwide market for all makes of carbon fiber tripods at roughly 100,000 units annually, and growing strongly due to increasing sales of high-end, digital SLR cameras. In 2004, carbon fiber tripods constituted 60 percent of Gitzo's U.S. professional sales, and Stailey expects this figure to reach 75 percent in 2005 or 2006.
