Thin Ply Prepregs

The recently announced collaboration of U.K.-based Fibre Mechanics and the Swiss company North Thin Ply Technology (NTPT) almost seems like Samsung and Apple working together to make better smartphones, on a much smaller scale, of course. In short, their aim is to lower costs and improve quality in the manufacture of high-end composite yachts through automation. No, we’re not talking robots. But we are talking ATL (Automated Tape Laying or “prepreg plotter”) machines. First, some background.

thin ply prepregsCourtesy NTPT

North Thin Ply Technology’s (NTPT) thin ply prepregs are manufactured using proprietary spread tow technology, which spreads untwisted fiber tows into thin, flat, unidirectional (UD) tapes, which are then combined with resin to create preimpregnated (prepreg) tapes. The evenly distributed, very straight fibers result in composite laminates with a much more uniform microstructure than those produced using conventional multiaxial 
or woven-fabric prepregs.

NTPT developed its Thin Ply Technology in 2001, which initially was for making sails. In 2005 it made the black carbon sails for the Swiss challenger for the America’s Cup, Alinghi, which won the 2007 event. That prompted North Sails to buy the technology and brand it 3Di. The next applications were for rigid composites such as Burton snowboards. By 2009 Southern Spars, another member of the North Technology Group (Edgewater Power Boats, Hall Spars), began using it to make carbon fiber masts, booms, and poles. In 2012 NTPT began working with makers of Formula 1 race­cars for body panels and aerospace, and more recently, working with watchmakers. (NTPT won an innovation award for the development of its TPT Quartz—a prepreg-fused quartz infused with Reichhold’s hot-melt monomer-free vinyl hybrid resin—to manufacture a Richard Mille watch case.) Tapes can be made from carbon fiber, fiberglass, quartz, PBO, and others. The sky, or rather outer space, seems to be the limit.

Fibre Mechanics is a new custom boatbuilder founded last year by runaways from Green Marine. Principal Geoff Stock worked for Jeremy Rogers in the early ’80s, studied yacht design at Southampton Institute, worked eight years at SP Systems (now Gurit), and spent two long stints at Green Marine, enmeshed in the evolving systems of epoxy wet layup, wet-preg, and on to the 90° prepregs in current employ­ment. He says the challenge was to “bond honey­comb cores to carbon skins in a reliable way, always a bit hit-and-miss with wet laminating resin.” Joining Stock in the new endeavor were Adrian Gillitt, Eliot Thorne, Gary Vaughan, and James Day, all of whom once worked at Green Marine.

According to Stock, their collective aim is to “increase the level of engineering sophistication” in marine composites by automating production processes. Part of that sophistication is to apply the same rigor to systems and fit-out as they apply to structure. Too often, he says, weight savings in hull and deck is given away elsewhere in the build, such as in the way equipment is attached to the structure.

automated tape-laying machineCourtesy NTPT

NTPT operates and sells an Automated Tape Laying machine that “lays down” 12″-wide (300mm) prepreg tapes on a table to form computer-designed panels of fabric.

The ATL machine “lays down” prepreg tapes of weights from 15 gsm to 600 gsm (0.44 oz/sq yd to 17.7 oz/sq yd) on a table. Standard width is 300mm (12). Tapes are laid down side by side without overlap; CEO James Austin says the natural tack of the prepreg material “causes the layers to stick together, making an integrated material.” As with CNC machines, plotting software allows curves to be drawn and cut to fit the mold into which the fabric tapes will later be fitted. Composites designers can specify custom preforms in which a stack of plies of unidirectional tapes are laid down by the ATL, selecting the orientation of each ply from 0° to 360º. Panels can be made up to 3.3m x 9.9m (10.8 x 32.5) and cured in Fibre Mechanics’ two autoclaves. It’s claimed that the ATL machine can equal the output of eight to 10 laminators, laying down 2,000 linear meters of laminate in a day.

With plants in the U.K. and Poland, Fibre Mechanics will handle client relations, and the manufacture of CNC-cut core kits and core inserts, while NTPT will make the unidirectional prepregs and preforms at its facility in Poland. The core and insert kits will be sent to Poland to be joined with the preforms and made into panels by NTPT, under Fibre Mechanics’ boatbuilding team.

Fibre Mechanics, Waterloo Rd., Lym­ing­ton, Hampshire SO41 9DB, U.K., tel. +44 (0) 1590 427007, website www.fibremechanics.com.

NTPT, Chemin du Closel 3, 1020 Ren­­ens, Switzerland, tel. +41 21 811 08 88, website www.thinplytechnology.com.