Antimagnetic watch
Encyclopedia
Anti-magnetic watches are those that are able to run with minimal deviation when exposed to a certain magnetic field. The International Organization for Standardization
issued a standard for magnetic resistant watches, which many countries have adopted.
8309 (Deutsche Industrie Norm - German Industry Norm) a watch
must resist exposition to a direct current magnetic field
of 4 800 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 4 800 A/m.
There are two ways of building an anti-magnetic watch:
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: the palladium
-made balance wheel
, balance spring
and the lever shaft.
In 1896 Charles Edouard Guillaume
discovered the nickel based alloy Invar. Afterwards, in 1920, when he received the Nobel Prize
in Physics
, 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. Later, in 1929, Tissot
assembled the first ever non-magnetic wristwatch.
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.
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.
In 1989 IWC first manufactured its Ingenieur which was able to withstand huge magnetic fields of up to 500,000 A/m.
The Rolex Milgauss
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.
International Organization for Standardization
The International Organization for Standardization , widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations. Founded on February 23, 1947, the organization promulgates worldwide proprietary, industrial and commercial...
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 DINDin
DIN or Din or din can have several meanings:* A din is a loud noise.* Dīn, an Arabic term meaning "religion" or "way of life".* Din is one of the ten aspects of the Ein Sof in Kabbalah ....
8309 (Deutsche Industrie Norm - German Industry Norm) a watch
Watch
A watch is a small timepiece, typically worn either on the wrist or attached on a chain and carried in a pocket, with wristwatches being the most common type of watch used today. They evolved in the 17th century from spring powered clocks, which appeared in the 15th century. The first watches were...
must resist exposition to a direct current magnetic field
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...
of 4 800 A
Ampere
The ampere , often shortened to amp, is the SI unit of electric current and is one of the seven SI base units. It is named after André-Marie Ampère , French mathematician and physicist, considered the father of electrodynamics...
/m
Metre
The metre , symbol m, is the base unit of length in the International System of Units . Originally intended to be one ten-millionth of the distance from the Earth's equator to the North Pole , its definition has been periodically refined to reflect growing knowledge of metrology...
. 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 4 800 A/m.
There are two ways of building an anti-magnetic watch:
- The first way consists in using different alloys, capable of withstanding magnetic fields. These alloys include InvarInvarInvar, also known generically as FeNi36 , is a nickel steel alloy notable for its uniquely low coefficient of thermal expansion . The name, Invar, comes from the word invariable, referring to its lack of expansion or contraction with temperature changes.It was invented in 1896 by Swiss scientist...
(ironIronIron is a chemical element with the symbol Fe and atomic number 26. It is a metal in the first transition series. It is the most common element forming the planet Earth as a whole, forming much of Earth's outer and inner core. It is the fourth most common element in the Earth's crust...
- nickelNickelNickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
- carbonCarbonCarbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
- chromiumChromiumChromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable...
alloy), GlucydurGlucydurGlucydur is the trade name of a metal alloy with a low coefficient of thermal expansion, used for making balance wheels and other parts of mechanical watches.Glucydur is a beryllium bronze; an alloy of beryllium, copper and iron...
(berylliumBerylliumBeryllium is the chemical element with the symbol Be and atomic number 4. It is a divalent element which occurs naturally only in combination with other elements in minerals. Notable gemstones which contain beryllium include beryl and chrysoberyl...
- bronzeBronzeBronze is a metal alloy consisting primarily of copper, usually with tin as the main additive. It is hard and brittle, and it was particularly significant in antiquity, so much so that the Bronze Age was named after the metal...
alloy), NivaroxNivaroxNivarox is a Swiss company formed by a merger in 1984 between Nivarox SA and Fabriques d'Assortiments Réunis . It is currently owned by the Swatch Group. Nivarox is also the trade name of the metallic alloy from which its products are fabricated...
(iron - nickel - chromium - titaniumTitaniumTitanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....
- beryllium alloy) and ElinvarElinvarElinvar is a nickel steel alloy with a modulus of elasticity which does not change much with temperature changes. The name is a contraction of the French elasticité invariable. It was invented in the late 1890s by Charles Édouard Guillaume, a Swiss physicist who also invented Invar, another...
- an alloy similar to Invar, though less resistant to magnetismMagnetismMagnetism is a property of materials that respond at an atomic or subatomic level to an applied magnetic field. Ferromagnetism is the strongest and most familiar type of magnetism. It is responsible for the behavior of permanent magnets, which produce their own persistent magnetic fields, as well...
and more resistant to thermal influence. These alloys are preferred by different watchmakers due to their differing properties. Since the 1950s, Nivarox and Glucydur were extensively used by watchmakers. In the 1960s, almost all Swiss watches had Glucydur balance and Nivarox hairsprings. 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 conductive (permeable) material. The movement is covered by an additional soft-iron clasp to prevent the forming of magnetic fields inside the watch itself. (See Faraday CageFaraday cageA Faraday cage or Faraday shield is an enclosure formed by conducting material or by a mesh of such material. Such an enclosure blocks out external static and non-static electric fields...
.)
History
The first recorded experiments in anti-magnetic watch-making are in 1846. Watchmakers from Vacheron ConstantinVacheron Constantin
Vacheron Constantin is a Swiss manufacture of prestige watches and a brand of the Richemont group. Considered by watch enthusiasts to be one of the finest traditional watch makers in the world along with Patek Philippe & Co., Jaeger-LeCoultre and Audemars Piguet.It employs around 400 people...
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: the palladium
Palladium
Palladium is a chemical element with the chemical symbol Pd and an atomic number of 46. It is a rare and lustrous silvery-white metal discovered in 1803 by William Hyde Wollaston. He named it after the asteroid Pallas, which was itself named after the epithet of the Greek goddess Athena, acquired...
-made balance wheel
Balance wheel
The balance wheel is the timekeeping device used in mechanical watches and some 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 spiral spring, the balance spring or hairspring...
, balance spring
Balance spring
A balance spring, or hairspring, is a part used in mechanical timepieces. The balance spring, attached to the balance wheel, controls the speed at which the wheels of the timepiece turn, and thus the rate of movement of the hands...
and the lever shaft.
In 1896 Charles Edouard Guillaume
Charles Edouard Guillaume
Charles Édouard Guillaume was a Swiss physicist who received the Nobel Prize in Physics in 1920 in recognition of the service he had rendered to precision measurements in physics by his discovery of anomalies in nickel steel alloys.Guillaume is known for his discovery of nickel-steel alloys he...
discovered the nickel based alloy Invar. Afterwards, in 1920, when he received the Nobel Prize
Nobel Prize
The Nobel Prizes are annual international awards bestowed by Scandinavian committees in recognition of cultural and scientific advances. The will of the Swedish chemist Alfred Nobel, the inventor of dynamite, established the prizes in 1895...
in Physics
Physics
Physics is a natural science that involves the study of matter and its motion through spacetime, along with related concepts such as energy and force. More broadly, it is the general analysis of nature, conducted in order to understand how the universe behaves.Physics is one of the oldest academic...
, 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. Later, in 1929, Tissot
Tissot
Tissot is a luxury Swiss watchmaker company founded in 1853 by Charles-Félicien Tissot and his son Charles-Émile Tissot who established the Tissot factory in the Swiss city of Le Locle, in the Neuchâtel area of the Jura Mountains....
assembled the first ever non-magnetic wristwatch.
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
Water resistance
Water resistance may refer to:* wet strength, a measure of how well a fibreweb is holds together upon a force of rupture* waterproofing, making objects relatively unaffected by water or resisting the ingress of water under specified conditions...
, sufficiently luminous
Luminosity
Luminosity is a measurement of brightness.-In photometry and color imaging:In photometry, luminosity is sometimes incorrectly used to refer to luminance, which is the density of luminous intensity in a given direction. The SI unit for luminance is candela per square metre.The luminosity function...
, shock resistant
Shock resistant watch
Shock resistant is a common mark stamped on the back of wrist watches to indicate how well a watch copes with shocks.-ISO 1413 shock-resistant standard:...
and have solid straps.
Contributions
In 1989 IWC first manufactured its Ingenieur which was able to withstand huge magnetic fields of up to 500,000 A/m.
The Rolex Milgauss
Rolex Milgauss
The Rolex Oyster Perpetual Milgauss is a highly collectible model introduced by Rolex in 1956 with the model number 6451. The Milgauss was designed as an antimagnetic watch specifically for those who worked in power plants, medical facilities and research labs where electromagnetic fields can...
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.
See also
- WatchWatchA watch is a small timepiece, typically worn either on the wrist or attached on a chain and carried in a pocket, with wristwatches being the most common type of watch used today. They evolved in the 17th century from spring powered clocks, which appeared in the 15th century. The first watches were...
- Diving watchDiving watchA diving 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 resistance of around , though modern technology allows the creation of diving watches that can go much deeper...
- Shock resistant watchShock resistant watchShock resistant is a common mark stamped on the back of wrist watches to indicate how well a watch copes with shocks.-ISO 1413 shock-resistant standard:...
- Water resistant watchWater Resistant markWater Resistant is a common mark stamped on the back of wrist watches to indicate how well a watch is sealed against the ingress of water. It is usually accompanied by an indication of the static test pressure that a sample of newly manufactured watches were exposed to in a leakage test...
- Milgauss