MAGNETIC FIELDS

Telecommunications, medical technology, the aerospace and electrotechnical industries are just a few of the many areas in which magnetic fields play a particularly important role. Magnetic fields strongly affect the rate of mechanical watches by magnetizing the components in the movement, in particular the escapement and the oscillator, which are responsible for the watch’s precision. Depending on the intensity and the length of exposure to a magnetic field, the movement rate can be negatively influenced and the watch may even stop. The reliability and precision of a mechanical watch can be affected by a magnetic field of as little as 50 to 100 gauss (or 0.01 tesla, according to today’s unit of measure). As a general example, the strength of the magnetic field of an ordinary poster magnet at a distance of 5 mm is around 200 gauss.

HERITAGE AND EVOLUTION

In 1956 Rolex succeeded in outsmarting the effects of magnetic fields by designing a watch that resists interference of 1,000 gauss (0.1 tesla, or 80,000 A/m) while preserving its excellent chronometric performance. Today, several innovations contribute to the resistance of the Milgauss, a technological gem. Most notable of these is the magnetic shield inside the Oyster case. Made of two ferromagnetic alloys, this shield surrounds and protects the movement. It is engraved with a ‘B’ with an arrow above it, the symbol for magnetic flux density. This invention was patented in 1956 and has since been further improved. The brand has also enhanced two of the movement’s key parts, the oscillator and the escape wheel; since 2007, these have been made from paramagnetic materials.

THE MILGAUSS, SUPERLATIVE CHRONOMETER CERTIFIED

Like all Rolex watches, the Milgauss is covered by the Superlative Chronometer certification redefined by Rolex in 2015. This exclusive designation attests that every watch leaving the brand’s workshops has successfully undergone a series of tests conducted by Rolex in its own laboratories and according to its own criteria. These certification tests apply to the fully assembled watch, after casing the movement, guaranteeing superlative performance on the wrist in terms of precision, power reserve, waterproofness and self-winding. The Superlative Chronometer status is symbolized by the green seal that comes with every Rolex watch and is coupled with an international five-year guarantee.

The precision of every movement – officially certified as a chronometer by the Swiss Official Chronometer Testing Institute (COSC) – is tested a second time by Rolex after being cased, to ensure that it meets criteria that are far stricter than those of the official certification. The precision of a Rolex Superlative Chronometer is of the order of −2/+2 seconds per day – the rate deviation tolerated by the brand for a finished watch is significantly smaller than that accepted by COSC for official certification of the movement alone.

The Superlative Chronometer certification testing is carried out after casing using state-of-the-art equipment specially developed by Rolex and according to an exclusive methodology that simulates the conditions in which a watch is actually worn and more closely represents real-life experience. The entirely automated series of tests also checks the waterproofness, the self-winding capacity and the power reserve of 100 per cent of Rolex watches. These tests systematically complement the qualification testing upstream during development and production, in order to ensure the watches’ reliability, robustness, and resistance to magnetic fields and shocks.

THE OYSTER CASE, SYMBOL OF WATERPROOFNESS

The Oyster case of the Milgauss, 40 mm in diameter and guaranteed waterproof to a depth of 100 metres (330 feet), is a paragon of robustness and reliability. The middle case is crafted from a solid block of Oystersteel, a particularly corrosion-resistant alloy. The case back, edged with fine fluting, is hermetically screwed down with a special tool that allows only Rolex watchmakers to access the movement. The Twinlock winding crown, fitted with a double waterproofness system, screws down securely against the case. The crystal is made of virtually scratchproof sapphire. The waterproof Oyster case provides optimum protection for the Milgauss’s movement.

PERPETUAL CALIBRE 3131

The Milgauss is equipped with calibre 3131, a self-winding mechanical movement entirely developed and manufactured by Rolex. The architecture, manufacturing and innovative features of this movement make it exceptionally precise and reliable.

The oscillator of calibre 3131 has a large balance wheel with variable inertia regulated extremely precisely via gold Microstella nuts. It is held firmly in place by a height-adjustable traversing bridge enabling very stable positioning to increase shock resistance.

Calibre 3131 has a blue Parachrom hairspring, manufactured by Rolex in a paramagnetic alloy. Insensitive to magnetic fields, the Parachrom hairspring offers great stability in the face of temperature variations. It is equipped with a Rolex overcoil, ensuring its regularity in any position, and features a paramagnetic escape wheel made from nickel-phosphorus. 

Calibre 3131 is fitted with a self-winding module featuring a Perpetual rotor, which ensures continuous winding of the mainspring by harnessing the movements of the wrist to provide constant energy. It offers a power reserve of approximately 48 hours.

The movement of the Milgauss will be seen only by certified Rolex watchmakers, yet it is beautifully finished and decorated in keeping with the brand’s uncompromising quality standards.

BRACELET AND CLASP, SECURE AND COMFORTABLE

The Milgauss is fitted on a three-piece link Oyster bracelet in Oystersteel. The bracelet is equipped with a folding Oysterclasp, developed by Rolex, and with the Easylink comfort extension link, also created by the brand, which allows the wearer to easily increase the bracelet length by approximately 5 mm, for additional comfort in any circumstance.