Ski manufacturing techniques include: Laminated construction, torsion-box construction, and single-shell construction. Laminated skis are constructed by layering and compressing various materials together, such as steel and plastic. Torsion-box manufacturing involves wrapping a soft inner core with a hard outer material such as fiberglass sheeting. Single-Shell is a ski manufacturing process that encases a strong inner core with a fiberglass or plastic mold.
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Ski manufacturing primarily began in Norway. Skis traditionally were hand-carved out of a single piece of hardwood such as Hickory, Birchwood or Ash. These woods were used because of their density and ability to handle speed and shock resistance factors associated with ski racing. Because of Europe’s dwindling forests, the ability to find quality, plank, hardwood became difficult, which led to the invention of the laminated ski.[1] A laminated ski is a ski composed of two different types of wood which are glued together. A top layer of soft wood is glued to a thin layer under a surface of hardwood. This combination actually created skis which were much lighter and more maneuverable than the heavy, hardwood skis that preceded them . Although lighter and stronger, laminated skis did not wear well. The water-soluble glues used at the time failed; warping and splitting along the glue edges (delaminating) occurred frequently and rapidly. In 1922, a Norwegian skier Thorbjorn Nordby [2] developed strong, water-proof glue which stopped the problem of splitting, therefore developing a much tougher laminated ski. Research and design of laminated skis rapidly progressed. In 1933 a new design technology was introduced involving an outer hardwood shell completely encasing an inner layer of lighter wood, successfully eliminating spontaneously splitting glue lines. This early design eventually evolved into an advanced laminating technique which is referred to today as Single-shell casing technology. Beginning in the 1950s other materials, such as aluminum, foam, and flexible plastics, were introduced as possible alternatives to the use of wood in ski manufacturing.[3] It was during this design period that experimentation with fiberglass created the strong, flexible, lightweight skis which were early models of the skis that are primarily used today.
Skis design is based on complex scientific principles. Ski construction must address a variety of factors. A ski must be light enough to glide on top of the snow, but must also be strong enough to withstand the weight of the skier. Skis are built with a curvature in the length of the ski known as camber [4], which provides stability in uneven terrain and varying snow consistency. The ski must also have the ability to bend to optimize manoeuvrability and accommodate weight shifts during turning. All skis are designed with the same primary structure- a wood, steel, or foam core which is then surrounded by more durable water-resistant materials. Combinations of varying ski shapes, weights, lengths and widths are designed for different types of skiing, such as downhill or slalom skiing.
Laminated skis are built in layers. Materials such as fiberglass, steel, aluminum alloy, or plastic are layered and compressed above and below the core.[5] The ski is then sealed with heated glue. This manufacturing technique provides the greatest variety of skis due to its ability to use many different combinations of materials. Laminated construction is the most widely used manufacturing process in the ski industry today
Torsion-Box skis consist of an inner core which is wrapped in fiberglass sheeting or carbon fiber [6] The wrapping process produces a ski that maneuvers better than a laminate ski, therefore these skis are most appealing to higher level skiers .This process is more labor intensive and time consuming, therefore torsion-box skis are more expensive to produce.
Single-shell skis consist of a core which is encased by a fiberglass or flexible plastic shell [7] The core is pressed or injected into a hollow plastic or fiberglass shell. An adhesive coating is applied to complete and reinforce the core sealing process. Due to their lightweight composition, single-shell skis give skiers better control in turning and handle vibration and shock better than laminated or torsion-box skis. The simple, low-cost, manufacturing process of single-shelled skis allows a large number of skis to be mass produced at reasonable, affordable prices.
K2 is a major U.S. based ski manufacturing company. In 1961 they were one of the first companies to begin producing and distributing fiberglass skis. Today K2 is primarily renowned for its wide -variety of torsion-box ski designs. They sponsor several professional skiers and ski teams.
Rossignol is a French company established in 1907. Rossignol introduced its first fiberglass ski in 1964. Today the company offers a wide range of ski designs and produces over 500,000 pairs of skis per year. Rossignol also manufactures boots, bindings, and poles.