| Pictured above, l to r: Alter Ego watch; waterproof chronometer watch with 38 rubies and
circular slide rule by Breitling SA; and Calvin Klein "Chainlink."
|
Portuguese Chronograph watch by International Watch Company |
Heuer Monza |
| Double Chronograph watch by International Watch Company |
| Sapphire scratch-resistant crystal by Longines |
Nickel magazine, Sep. 01 -- Despite the popularity of electronic watches and the
prediction that they would completely replace traditional mechanical watches, the latter have survived and
are making a strong come-back, especially in the high-quality, luxury market.
Until about 10 or 15 years ago, the cases and bracelets of the most expensive, luxurious wrist watches were
made of precious metals, mostly gold in all its many different colours. Nickel- containing stainless steels
were preferred only by adventurous types such as pilots, divers, astronauts, explorers, scientists and
military officers. But recent years have seen a shift toward nickel stainless steel for even the most
exclusive, luxurious watches.
A generation ago, one bought a gold watch and kept it for life. Today, it is not uncommon for one to have several watches made of nickel stainless steel -- a different one for each social occasion. A similar trend is true for jewelry. This is not surprising, given today's high-priced watches often resemble jewelry. Time-keeping is now just one of the many functions performed by wrist watches; resisting water pressure and corrosion is another.
The market breakthrough came with the ability to mount precious stones on stainless steel. Compared with precious metals, stainless is extremely hard, making it difficult to work; it was therefore a challenge to cut it with precision, make the necessary holes, and integrate prongs required to hold the stones.
The first nickel stainless steel wrist watches appeared in 1930, since which time their use has steadily increased. In 1999, the value of nickel stainless steel watches produced in Switzerland reached 40% of the value of all watches made of precious metals.
The nickel stainless steel alloys used for watch cases and bracelets are all highly resistant to corrosion, in particular to seawater and sweat. Typical examples of the high- quality nickel stainless steel alloys used for watches and bracelets are EN 1.4404 and EN 1.4435 (both S31603), and EN 1.4539 (UNS N08904). Although they contain nickel, these alloys will not raise concerns about nickel allergy. That's because nickel allergy occurs when the corrosion products of certain insufficiently corrosion-resistant alloys come into direct and prolonged contact with the skin. If an alloy is of sufficient high quality that no corrosion products are produced, there will be no risk of nickel allergy.
Watch manufacturers, particularly in Switzerland, demand strict adherence to chemical compositions and various special properties, all of which are found in nickel stainless steels. These include specific surface finishes, low residual magnetism, a pleasing colour and high mechanical strength for resisting deformation under water pressures at depths of 500 metres or more. High-purity alloys are important as well, because different surface finishes on watch cases and bracelets are often situated very close to each other. For example, a mirror polish can be combined with a brushed, satin or micro-shot blasted finish. Impurities or certain compositions can make finishes less perfect. Nickel stainless steel watch cases and other parts are also produced by metal powder injection-molding, allowing, through the selection of pure powders, made-to-measure chemical compositions.
For nearly 70 years, nickel stainless steels have allowed the Swiss watch-making industry to take
advantage of the material's outstanding properties. At the same time, the industry has gained extensive
knowledge in transforming these alloys into cases, bracelets and other parts of outstanding beauty and
quality. In this sense, they are truly "noble" alloys.
By Alfred Bauer, a Switzerland-based consultant to the Nickel
Development Institute.
S I D E B A R
Stainless offers strength and anti-magnetism
The makers of precious jewelry depended, for a long time, on two noble metals -- gold and silver. Both could be found in nature ready-made in metallic form, without the need for processing of ores, and, because of their extraordinary malleability and softness, they could be easily worked and transformed into any shape. In addition to their intrinsic value, gold and silver have outstanding corrosion resistance, which partly accounts for their status as "noble" metals.
Today, gold and silver in their pure form are only used for special purposes (and the latter has lost its previous importance in many applications). For jewelry, bracelets and wrist watches, improved mechanical properties were needed. With gold, these properties were achieved by alloying the metal with copper and silver. White gold is often made by adding palladium, whereas rose gold contains less silver and more copper. Despite modern technology, gold alloys have limits when higher strength and abrasion resistance are demanded
For watches and bracelets, the industry was quick to realize, many decades ago, the advantages of nickel stainless steels, as they have the combination of properties needed: anti-magnetism, high strength, and the choice of many different finishes. Also, nickel stainless can be machined and finished to the high standards required for specialized watch-making, and its resistance to corrosion is excellent.
There are emotional reasons for the renewed popularity of mechanical watches. People are fascinated by the "living" high-precision mechanism, characterized by the rapid alternating movement of the balance wheel and the attached spiral spring. In addition to the date display and the automatic rewinding of the main spring, mechanical watches can be equipped with so-called "complications." These are mechanisms that show the perpetual calendar (mechanically programmed for example until the year 2499), the day of the week, the month, and the phase of the moon. Additional complications include a programmable and repeatable alarm, time display for three time zones, and countdown timer for racing events. Mechanical watches can also be equipped with a "tourbillon," a device that compensates for the effect of the earth's gravity on the balance wheel.
Many expensive and luxurious wrist watches come with a certificate of the Swiss Official Control of Chronometers, confirming the exact time-keeping in five positions at four different temperatures. Certification also ensures resistance to magnetic influences and water pressure. A mechanical chronometer may not deviate more than six seconds fast or four seconds slow in 24 hours, corresponding to a precision of 99.99%.
Photo: AUDEMARS PIGET, BREITLING SA, LONGINES, TAG HEUER, INTERNATIONAL WATCH COMPANY, CALVIN KLEIN
