Barbell Plate
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A weight plate is a flat, heavy object, usually made of
cast iron Cast iron is a class of iron–carbon alloys with a carbon content of more than 2% and silicon content around 1–3%. Its usefulness derives from its relatively low melting temperature. The alloying elements determine the form in which its car ...
, that is used in combination with
barbell A barbell is a piece of exercise equipment used in weight training, bodybuilding, Olympic weightlifting, weightlifting, powerlifting and strongman, consisting of a long bar, usually with weights attached at each end. Barbells range in length ...
s or
dumbbells The dumbbell, a type of free weight, is a piece of equipment used in weight training. It is usually used individually and/or in pairs, with one in each hand. History The forerunner of the dumbbell, halteres, were used in ancient Greece as li ...
to produce a bar with a desired total weight for the purpose of
physical exercise Exercise or workout is physical activity that enhances or maintains fitness and overall health. It is performed for various reasons, including weight loss or maintenance, to aid growth and improve strength, develop muscles and the cardio ...
. Two general categories exist: "standard" plates, which have a center hole of approximately 25 mm (one inch), and "Olympic" plates, meant to fit on the 50 mm (two inches) sleeves of Olympic barbells. Standard plates are usually paired with adjustable dumbbells and Olympic plates with full-size barbells, although standard barbells and Olympic dumbbells exist. Weight plates may incorporate holes for ease of carrying (called "grip plates") or be solid discs (especially those used for competition). Non-competition plates often have variable diameters and widths, such as on the adjustable dumbbells pictured right, with heavier plates generally being larger in diameter, thickness, or both. Weight plates are typically round, although 12-sided and other
polygon In geometry, a polygon () is a plane figure made up of line segments connected to form a closed polygonal chain. The segments of a closed polygonal chain are called its '' edges'' or ''sides''. The points where two edges meet are the polygon ...
al varieties exist. Most plates are coated with
enamel paint Enamel paint is paint that air-dries to a hard, usually glossy, finish, used for coating surfaces that are outdoors or otherwise subject to hard wear or variations in temperature; it should not be confused with decorated objects in "painted enam ...
or
hammertone Hammer paint (or hammered paint) is a special lacquer with a surface that looks like hammered metal when dried. It is also known as hammertone. Composition The slightly iridescent areas are caused by the different orientation of very small shiny ...
to resist corrosion; more expensive varieties may be coated with chrome, rubber, or plastic.


Plate sizes

Plates are available in a range of weights. Common Olympic plate (50 mm center hole) denominations are in 1.25, 2.5, 5, 10, 15, 20, and 25 kg sizes, or 2.5, 5, 10, 25, 35, and 45 lbs, with 0.25, 0.5, and 50 kg, or 1.25 and 100 lb discs less commonly seen. Standard plates (25mm center hole) are commonly available in 1.25, 2.5, 5, 10, 15, and 20 kg, or 2.5, 5, 10, 25, 35 and 50 lb where pound denominated plates are used. Less commonly seen are plates of 0.5, 7.5, and 25 kg, or 1.25, 7.5, 12.5, 20, and 100 lbs. Bumper plates are commonly available in 5, 10, 15, 20, and 25 kg, or 10, 15, 25, 35, 45, and 55 lb in pound-denominated sets.


Weight accuracy

Low-cost plates can vary widely from their marked weight. A 2% or 3% variation is not uncommon, with plates from some manufacturers frequently being 10% or more over or under (a 45-pound plate can weigh as little as 40 pounds, or as much as 50). Tom Lincir, founder of the Ivanko Barbell Company, has encountered plates weighing as little as , or as much as . Plates can be weighed, and the equipment marked (using a
paint pen A paint marker is a type of marker pen that is used to create permanent writing on a variety of surfaces such as paper, metal, stone, rubber, plastic, and glass. Ink Unlike with most permanent markers the ink is an oil-based paint and generally re ...
or other
permanent marker A permanent marker or indelible marker is a type of marker pen that is used to create permanent or semi-permanent writing on an object. Description In general, permanent marker ink comprises a main carrier solvent, a glyceride, a 2-Pyrrolidon ...
) with the true weight. Calibrated plates are available from high-end manufacturers; many advertise these plates as being accurate to within of marked weight, which is the tolerance mandated by the
International Weightlifting Federation The International Weightlifting Federation, aka IWF, is the international governing body for the sport of Weightlifting. Headquartered in Lausanne, Switzerland, it has 193 affiliated national federations. Mohammed Hasan Jalood has been its presid ...
for plates used in competition.


Bumper plates

Olympic plates may come in the form of bumper plates, which are made of resilient rubber. These are used for
Olympic weightlifting Weightlifting (often known as Olympic weightlifting) is a competitive strength athletics, strength sport in which athletes compete in lifting a barbell loaded with weight plates from the ground to overhead, with the aim of successfully lifting t ...
, a category of movements that involve lifting a barbell high overhead, then letting it fall. Their design permits a loaded barbell to be dropped (and to bounce) after a lift, with negligible damage to the floor, plates, and bar. Unlike most iron plates, where heavier plates have larger diameters, bumper plates are all the same diameter, instead varying in thickness and construction. This helps to distribute the force of the dropped barbell across all the plates more evenly, reducing damage to the equipment. Lower-end bumper plates are generally made of solid rubber with a steel or brass hub. Competition-grade bumper plates are more compact, with a layer of rubber surrounding a steel core. Bumper plates used in competition have a diameter mandated by the
International Weightlifting Federation The International Weightlifting Federation, aka IWF, is the international governing body for the sport of Weightlifting. Headquartered in Lausanne, Switzerland, it has 193 affiliated national federations. Mohammed Hasan Jalood has been its presid ...
of ±, with lighter plates being narrower than heavier plates. The lightest bumper plates available are generally , or in pound-denominated sets. Plates lighter than this are generally smaller in diameter and are known as "change plates" when paired with bumper plates. As an alternative to rubber plates, "technique plates", made of plastic, are available. Technique plates are more expensive than rubber, but hold up better to repeated drops. Their primary purpose is to allow novice lifters to practice
Olympic lifts Weightlifting (often known as Olympic weightlifting) is a competitive strength sport in which athletes compete in lifting a barbell loaded with weight plates from the ground to overhead, with the aim of successfully lifting the heaviest weights ...
at lighter weights that can put too much lateral stress on single pairs of rubber plates, damaging them.


Vinyl plates

Standard (25 mm hole) "vinyl" plates are often sold paired with dumbbells or barbells as a low-cost option for casual strength training. These plates are made of cement or sand coated with a
polyvinyl chloride Polyvinyl chloride (alternatively: poly(vinyl chloride), colloquial: vinyl or polyvinyl; abbreviated: PVC) is the world's third-most widely produced synthetic polymer of plastic (after polyethylene and polypropylene). About 40 million tons of ...
sheath. The cement tends to break down over time and leak out of holes in the sheath, and the weights are less dense than iron so that fewer fit on a given bar.


Weight stacks

Weight machine A weight machine is an exercise machine used for weight training that uses gravity as the primary source of resistance and a combination of simple machines to convey that resistance to the person using the machine. Each of the simple machines (p ...
s commonly use specialized sets of plates (called "weight stacks"), consisting of a set of rectangular plates mounted on rails. Through a cable and pulley system, the burden is transferred to the machine's user. By placing a pin in the stack that causes the cable to pull on each plate above the pin, the weight is selected. We refer to this configuration as a "selectorized" weight machine. Some weight machines, such as the sled-type
leg press The leg press is a compound weight training exercise in which the individual pushes a weight or resistance away from them using their legs. The term ''leg press machine'' refers to the apparatus used to perform this exercise. The leg press can be ...
, or the
Smith machine The Smith machine is a weight machine used for weight training. It consists of a barbell that is fixed within steel rails allowing for only strict vertical movement. Some Smith machines have the barbell counterbalanced. The machine can be used for ...
, are designed to be loaded with Olympic plates instead of using a cable-driven stack.


References


External links

* {{commons category-inline, Weight plates Weight training equipment