Anti-magnetic (non-magnetic) watches are those that are able to run with minimal deviation when exposed to a certain level of magnetic field. The

International Organization for Standardization The International Organization for Standardization (ISO ) is an international standard development organization composed of representatives from the national standards organizations of member countries. Membership requirements are given in Art ...

issued a standard for magnetic-resistant watches, which many countries have adopted.

ISO 764 magnetic-resistant watches standard

The international standard ISO 764 Horology—Magnetic resistant watches defines the resistance of watches to magnetic fields. According to ISO 764 or its equivalent DIN 8309 (Deutsches Institut für Normung - German Institute for Standardization) a

watch A watch is a portable timepiece intended to be carried or worn by a person. It is designed to keep a consistent movement despite the motions caused by the person's activities. A wristwatch is designed to be worn around the wrist, attached b ...

must resist exposure to a direct current magnetic field of 4800 A/ m. The watch must keep its accuracy to ±30 seconds/day as measured before the test in order to be acknowledged as a magnetic-resistant watch. Annex A of ISO 764 deals with watches designated as magnetic resistant with an additional indication of intensity of a magnetic field exceeding 4800 A/m. There are two ways of building an anti-magnetic watch: * The first way consists of making the moving parts of

alloys An alloy is a mixture of chemical elements of which at least one is a metal. Unlike chemical compounds with metallic bases, an alloy will retain all the properties of a metal in the resulting material, such as electrical conductivity, ductility ...

chosen to be insensitive to magnetic fields. These alloys include

Invar Invar, also known generically as FeNi36 (64FeNi in the US), is a nickel–iron alloy notable for its uniquely low coefficient of thermal expansion (CTE or α). The name ''Invar'' comes from the word ''invariable'', referring to its relative lac ...

(

iron Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundanc ...

–

nickel Nickel is a chemical element with symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel is a hard and ductile transition metal. Pure nickel is chemically reactive but large pieces are slow ...

–

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon mak ...

– chromium alloy), Glucydur (

beryllium Beryllium is a chemical element with the symbol Be and atomic number 4. It is a steel-gray, strong, lightweight and brittle alkaline earth metal. It is a divalent element that occurs naturally only in combination with other elements to form m ...

– bronze alloy),

Nivarox Nivarox, also known as Nivarox - FAR SA is a Swiss company formed by a merger in 1984 between Nivarox SA and Fabriques d' Assortiments Réunis (FAR). It is currently owned by the Swatch Group. Nivarox is also the trade name of the metallic alloy fro ...

(iron–nickel–chromium–

titanium Titanium is a chemical element with the Symbol (chemistry), symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resista ...

–beryllium alloy) and

Elinvar Elinvar is a nickel–iron–chromium alloy notable for having a modulus of elasticity which does not change much with temperature changes. The name is a contraction of the French ('invariable elasticity'). It was invented by Charles Édouard Guil ...

(an alloy similar to Invar, though less resistant to magnetism and more resistant to thermal influence). These alloys are preferred by different watchmakers due to their differing properties. In the 1960s, almost all Swiss watches had Glucydur balance and Nivarox

hairspring A balance spring, or hairspring, is a spring attached to the balance wheel in mechanical timepieces. It causes the balance wheel to oscillate with a resonant frequency when the timepiece is running, which controls the speed at which the wheels of t ...

s. The anchors, escape wheels and other watch mechanisms were also made of non-magnetic metals or alloys. * Another way of making a watch non-magnetic is to house the entire movement into a case made of a highly

permeable Permeability, permeable, and semipermeable may refer to: Chemistry *Semipermeable membrane, a membrane which will allow certain molecules or ions to pass through it by diffusion *Vascular permeability, the movement of fluids and molecules betwe ...

(magnetically conductive) material. The movement is covered by an additional soft-iron clasp to prevent the forming of magnetic fields inside the watch itself.

History

The first recorded experiments in anti-magnetic watch-making are in 1846. Watchmakers from

Vacheron Constantin Vacheron Constantin SA () is a Swiss luxury watch and clock manufacturer founded in 1755. Since 1996, it has been a subsidiary of the Swiss Richemont Group. Vacheron Constantin is the second oldest Swiss manufacturer and one of the oldest wat ...

were among the first to experiment with anti-magnetic features of a watch. However, they succeeded in assembling the first antimagnetic watch only several decades later. That watch was able to withstand magnetic fields because some of its parts were made of non-magnetic

metals A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typical ...

: the

palladium Palladium is a chemical element with the symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1803 by the English chemist William Hyde Wollaston. He named it after the asteroid Pallas, which was itself na ...

-made

balance wheel A balance wheel, or balance, is the timekeeping device used in mechanical watches and small clocks, analogous to the pendulum in a pendulum clock. It is a weighted wheel that rotates back and forth, being returned toward its center position by a ...

balance spring A balance spring, or hairspring, is a spring attached to the balance wheel in mechanical timepieces. It causes the balance wheel to oscillate with a resonant frequency when the timepiece is running, which controls the speed at which the wheels of ...

and the lever shaft. In 1896

Charles Édouard Guillaume Charles Édouard Guillaume (15 February 1861, in Fleurier, Switzerland – 13 May 1938, in Sèvres, France) was a Swiss physicist who received the Nobel Prize in Physics in 1920 in recognition of the service he had rendered to precision measuremen ...

discovered the nickel based alloy Invar. Afterwards, in 1920, when he received the

Nobel Prize The Nobel Prizes ( ; sv, Nobelpriset ; no, Nobelprisen ) are five separate prizes that, according to Alfred Nobel's will of 1895, are awarded to "those who, during the preceding year, have conferred the greatest benefit to humankind." Alfr ...

Physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...

, he developed another alloy - Elinvar. These alloys assisted in the assembly of anti-magnetic watches. Invar and Elinvar are able to resist magnetic fields, allowing the watch to continue to keep accurate time. The first anti-magnetic pocket watch was assembled by Vacheron Constantin in 1915. In 1930,

Tissot Tissot SA () is a Swiss watchmaker. The company was founded in Le Locle, Switzerland by Charles-Félicien Tissot and his son, Charles-Émile Tissot, in 1853. After several mergers and name changes, the group which Tissot SA belonged to was renam ...

produced the first ever non-magnetic

wristwatch A watch is a portable timepiece intended to be carried or worn by a person. It is designed to keep a consistent movement despite the motions caused by the person's activities. A wristwatch is designed to be worn around the wrist, attached by ...

Usage

Since their appearance, anti-magnetic watches have been favored by people who deal with high magnetic fields. They are widespread among electronic engineers and in other professions where strong magnetic fields are present. Today, even divers' watches (according to ISO 6425) must be anti-magnetic as well as being water resistant, sufficiently luminous, shock resistant and have solid straps.

Contributions

After discovering the alloys for assembling anti-magnetic watches, many watch-making brands utilize such materials in production in order to improve the performance of such timepieces.

IWC

In 1989 IWC first manufactured the Ingenieur Reference 3508, which was able to withstand huge magnetic fields of up to 500000 A/m.

Omega

The Omega Anti-Magnetic Seamasterwas announced
17 January 2013 (e.g. Seamaster Aqua Terra > 15,000 Gauss). According to the press release, the OMEGA movement does not rely on a protective container inside the watchcase but on the use of selected non-ferrous materials in the movement itself. The OMEGA prototype was subjected to 1.5 Tesla (15,000 Gauss) and continued to perform. Testing showed that the watch was as accurate after its magnetic exposure as it had been before.

Rolex

The

Rolex Milgauss The Rolex Oyster Perpetual Milgauss is a wristwatch model introduced by Rolex in 1956 with model number 6541. The Milgauss was advertised as “designed to meet the demands of the scientific community working around electromagnetic fields”. The ...

series of antimagnetic certified chronometers was first manufactured in 1954 with the model 6541 for those working in nuclear, aircraft, and medical settings associated with strong magnetic fields. The watch has an advertised magnetic flux density resistance of 1,000 Gauss within magnetic fields of 80,000 A/m. In 2007, after being out of production for nearly two decades a new Milgauss was introduced as the model number 116400.

Sinn

Certain

diving watch A diving watch, also commonly referred to as a diver's or dive watch, is a watch designed for underwater diving that features, as a minimum, a water resistance greater than , the equivalent of . The typical diver's watch will have a water resis ...

es produced by

Sinn In the philosophy of language, the distinction between sense and reference was an idea of the German philosopher and mathematician Gottlob Frege in 1892 (in his paper "On Sense and Reference"; German: "Über Sinn und Bedeutung"), reflecting the ...

as mission timers (in German: "Einsatzzeitmesser") for professional users are also protected against magnetic fields up to 1,000 Gauss / 80,000 A/m, using a protective sheath consisting of a closed, magnetically soft inner case that includes the dial, the movement holding ring and the case back.

METAS N001 requirements

The Swiss Federal Institute of Metrology (METAS) has METAS N001 requirements for movements and mechanical watches resistant to magnetic fields of 1.5 Tesla (15,000 Gauss). The METAS N001 certification demands a series of tests were amongst other relevant requirements the watches are subjected to strong magnetic field exposures without resulting in the movement stopping or a 0 to ≤5 seconds daily rate deviation.Certification of mechanical watches is in accordance with the METAS requirements N001
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References

External links

Vacheron Constantin and Nonmagnetic Watches
{{DEFAULTSORT:Antimagnetic Watch Watches