Anatomy of a Ski - Ski Mag

Anatomy of a Ski

Ever wonder what’s under that topsheet? Knowing won’t change your life, but it might change your mind.
Author:
Publish date:
Social count:
0

ANATOMY 

>Topsheet:

SKI-layers-4_t.jpg

The top layer of a ski, typically a sheet of clear plastic with the ski’s graphics printed on its underside

>Laminates:

Sheets of reinforcing material—usually metal or epoxy-impregnated fiberglass fabric—layered above and below the core

>Core:

The primary structural element—wood or foam—around which the ski is built. Some foam cores (the good ones) are milled to precise shapes from foam blanks, then laid into the ski mold; other foam cores (derisively known as “squirties”) are simply injected through the tail into a hollow shell of a ski (a cheap but imprecise manufacturing method). Most wood cores are made by laminating vertical strips of wood together (think plywood tipped on edge).

>Sidewall:

The vertical plastic side surface of a laminate-construction ski. Differing densities of material yield different performance characteristics between skis.

>Base:

A sheet of plastic, usually high-density polyethylene. Typically “structured” with micro-grooves—rather than mirror-smooth—to reduce suction and promote glide

>Edge:

A strip of stainless steel integrated into the layup

GLOSSARY

>Camber:

The curvature built into the length of the ski, so that the pressure of a skier’s weight is distributed to the tip and tail, giving them more grip on the snow

>Dampening:

The reduction of the vibrations that occur when a ski is in motion. A dampened ski is better able to hold an edge in the snow—but may lack liveliness.

>Dimensions:

Tip, waist and tail widths—an expression of the shape of a ski

>Midfat:

A loosely defined category of skis, prized for their versatility. They’re not as wide as specialized powder skis, nor as narrow as carving or race skis. Today’s midfats—typically 75 to 85 mm at the waist—are generally wider than those of recent years.

>Mold:

A steel plank with a ski-shaped cavity milled into it. Typically, ski components (and liberal amounts of epoxy) are placed into the mold, which is then subjected to intense heat and pressure to bond the components and squeeze out excess epoxy.

>Pre-preg:

A type of pre-fabricated laminate used to reinforce ski cores. Sheets of fiberglass fabric are impregnated with epoxy, cured, then cut to fit the ski’s width and placed in the mold.

>Sidecut:

The narrowing of a ski at its waist; aids in turning when the ski is tipped on edge and pressured into an arc

>Sidecut radius:

A measurement, in meters, of the depth of a ski’s sidecut curvature. The curve is extrapolated into an imaginary circle, and the radius of that circle describes the ski’s sidecut.

>Titanal:

The brand name of the titanium-aluminum alloy most commonly used in the manufacturing of skis

>Titanium:

A lustrous white metal prized for its strength-to-weight ratio; often alloyed with aluminum for use in skis

>Torsional rigidity:

A ski’s ability to resist twisting, often achieved by aligning glass fibers across the core at a 30- to 45-degree angle

BASIC CONSTRUCTION TYPES

>Cap:

A type of construction in which the top layer(s) arch from one edge to the other, so that the top of the ski is rounded, rather than flat. Sometimes the topsheet is strategically reinforced and plays a structural role (a “load-bearing cap”). Usually a topsheet is merely cosmetic, in which case performance attributes are determined by core design.

>Laminate or “Sandwich”:

Prized for its power and edge-hold. The ski is built—or “laid up”—in horizontal layers. Typical laminate construction: base sheet, then a sheet of pre-preg fiberglass, then a sheet of metal, then the core, then metal, then fiberglass, then topsheet.

>Torsion box:

A type of construction in which the core, usually wood, is encased in a sleeve of fiberglass, which is then epoxy-soaked and cured. So named because it resists twisting (see “torsional rigidity”) when the fibers are aligned at an angle across the core.

HOW A SKI IS MADE

We can’t help thinking about panini. You know how they’re made: layers of bread, meat and cheese, squished and cooked into cohesive goodness by a heated press. The best skis (those not made by injecting foam into a shell) are made in a similar fashion.

Instead of prosciutto di Parma and fontina, of course, we’re talking less tasty ingredients: plastics, wood, metals, fibers. Instead of melted cheese to hold it all together, there’s epoxy. And rather than using a panini mold, we’ll use a high-powered press designed to accept various ski molds (see Glossary above).

A factory worker starts with an empty mold and a supply of all the components needed to build skis of a certain length, shape and design. Into the mold go the ingredients, layer by layer: base and edge material on the bottom, then the vertical sidewalls over the edges, a couple of reinforcing laminates over the base (typically Titanal and/or pre-preg fiberglass) then the precisely milled core (wood, foam or a combination, sometimes wrapped in fiberglass, as in torsion-box construction). Above the core go one or two more laminates and finally the topsheet, a clear layer with the graphic printed on its underside. Into the heated press it goes, where pressure squeezes out any extra epoxy. The ski is then cleaned up and tuned. Once it’s cured, it’s ready for the slopes.

Related

Anatomy of a Ski 2012

Anatomy of a Ski: Base to Topsheet

Don't know your pre-preg from your torsion box? And what's so great about vertical sidewalls anyway? Skis have fairly simple constructions, but it helps to understand a few terms and concepts.

anatomy: boots

Anatomy of a Ski Boot

Whether you're in the market for new ski boots, or just want to get learned, we help you know your boot from liner to last.

Construction: torsion box

Anatomy: Skis

Don’t know your pre-preg from your torsion box? And what’s so great about vertical sidewalls anyway? Skis have fairly simple constructions, but it helps to understand a few terms and concepts.

anatomy: boots

Anatomy: Boots

Your first step to improving your skiing? Your boots. Here’s a look inside.

Parts of the whole

Anatomy: Helmet

New technology makes wearing a ski helmet a no-brainer. Still making excuses? Put a lid on it.