Collector’s Guides • 10 Aug 2017
Patek Philippe Advanced Research
Despite the generally conservative designs of its timepieces, Patek Phillipe is nevertheless also an innovator in watchmaking. In its 178-year history, the Genevan maison has developed dozens of complications and technical improvements, such as the Gyromax balance wheel almost 70 years ago, and more recently the annual calendar complication unveiled in 1996. The innovative spirit of the brand is embodied by a special series of watches that began in 2005 – the Advanced Research. The latest addition to this family was unveiled at Baselworld 2017: the Aquanaut Travel Time Advanced Research Ref. 5650G that boasts a one-piece, flexible time-zone mechanism.
The motivations behind Advanced Research
Precision and reliability have always the primary goals in watchmaking. For most of the last two centuries, however, the basic principles of the mechanical watch have changed little, so improvements to either have been incremental at best, with occasional paradigm shifts. For example, metal alloys have historically been used for nearly every component of the watch. At the turn of the millennium, however, material sciences and micromechanics reached a threshold to introduce new technologies to watchmaking, including the now widely used but occasionally controversial silicon.
As an independent manufacture, Patek has kept up with developing technologies, and teamed up with external institutions, including CSEM, a micro-engineering research laboratory, and the Swiss Federal Institute of Technology Lausanne (EPFL), to create proprietary technologies for its watches. That gave birth to the Patek Philippe Advanced Research series of timepieces, which was started in 2005 with the introduction of Silinvar.
2005 – Silinvar and the Ref. 5250 Annual Calendar
The first Advanced Research piece featured Silinvar, a silicon-based material that was used for the escape wheel. It was a novel, patented material based on mono-crystalline silicon, developed by CSEM in Neuchâtel, and jointly funded by Patek Philippe, Rolex, and the Swatch Group. Silinvar has several advantages for movement components, most notably its resistance to temperature changes ranging from -10 to +60 degrees Celsius, which explains its trade name, a contraction of “silicon” and “invariable”.
The material also requires no lubrication, thus doing away with oils that will dry up or migrate elsewhere. In addition, silicon is:
- Lightweight, with a density that’s just one third that of steel, which translates to lower inertia and less energy needed
- Twice as hard as steel and thus highly wear-resistant
- Non-magnetic and insensitive to magnetic fields
- Shock-resistant and slightly elastic, so it returns to its original shape with distortion
- Capable of being manufactured to a tolerance of less than a thousandth of a millimeter
The Silinvar escape wheel was first introduced in the ref. 5250 Annual Calendar Patek Philippe Advanced Research, a 100-piece limited edition. While highly classical in style and relying on the patented annual calendar launched in 1996, ref. 5250 was unique on the rear, with a sapphire “bubble” on the display back to magnify the silicon escape wheel underneath a specially designed bridge.
2006 – the Spiromax balance spring in Silinvar and the Ref. 5350 Annual Calendar
Based on the research done by CSEM, Patek Philippe decided to go further with the use of the innovative material by using it for other critical parts of the movement. The second step came just one year after the first Advanced Research Ref. 5250, with the introduction of Spiromax balance spring made of Silinvar.
The use of silicon for the hairspring offers several advantages compared to traditional alloys used in watchmaking:
- An improvement in the escapement’s precision – regardless of position – thanks to more concentric breathing (expansion and contraction) of the hairspring
- Lower mass and thus a reduction of sensitivity to external phenomena such as gravity or shocks
- A flat design that is two-thirds thinner than a traditional hairspring ending with a Breguet overcoil
The Spiromax balance was introduced in the ref. 5350R Annual Calendar Advanced Research, a 300-piece limited edition that combined both the Spiromax balance spring and the Silinvar escape wheel. The watch was again extremely classical looking, being nearly identical in design to the ref. 5250G, but in a pink gold case. Like its predecessor, the case back of the ref. 5350G featured a magnifier over the balance and its silicon hairspring.
Since then the Spiromax balance spring has been deployed in most Patek Philippe movements, including the calibers 240, 215, 28-520, and 324.
2008 – The Silinvar Pulsomax escapement and ref. 5450
In order to create a regulating organ (made up of the lever, escape wheel, hairspring and balance wheel) entirely out of silicon, Patek Philippe introduced the third installment in the Advanced Research series in 2008. That was the Pulsomax escapement, a new and improved escape wheel as well as lever in Silinvar.
The Pulsomax escapement boasted a gain of over 15 per cent in energy transmission thanks to an optimized geometry of the escape wheel and the lever, which allowed for extended service intervals. All the new innovations, including the Pulsomax escapement and the Spiromax balance spring, were packaged into a 300-piece limited edition, the Ref. 5450p Annual Calendar Advanced Research.
2011 – The final step with the Oscillomax ensemble and the ref. 5550 Perpetual Calendar
The final step of the development for the regulating organ came in 2011, when Patek Philippe unveiled the complete package of its innovative technologies, named the Oscillomax ensemble, comprising a gold-rimmed balance, escape wheel, lever, and hairspring – all executed in silicon.
The key advance with Oscillomax was the GyromaxSi balance wheel. It was based on the 1951 Gyromax principles, yet drastically improved with modern know-how.
The advances were myriad:
- All the precision adjustment advantages of the Gyromax balance (adjustment by changing regulating weights, this no disruptive alteration of the active length of the hairspring)
- Concentration of the effective mass at the periphery thanks to pure gold weights on the rim, to achieve greater inertia and oscillation stability
- Optimization of balance wheel aerodynamics with an efficiency gain of 15 per cent, due to the new shape
The Oscillomax was introduced in the Ref. 5550P Perpetual Calendar Patek Philippe Advanced Research, again in a 300-piece limited edition, but this was the first in the series that isn’t an annual calendar. And, unlike the earlier watches in the series that used the calibre 324 as a base, the ref. 5550P was powered by the micro-rotor calibre 240.
2017 – The new Spiromax balance spring, the new time-zone corrector with compliant (flexible) mechanism in steel, in the Aquanaut Travel Time Ref. 5650G
Six years after the last Advanced Research watch, Patek Philippe returned to the series at Baselworld 2017 with the Aquanaut Travel Time Ref. 5650G. The new watch features two key innovations, the first an update of the Spiromax, and the second an entirely new innovation.
The new Spiromax hairspring is still made of Silinvar, naturally, but with a new optimized shape. The outer boss is now paired with an inner boss, meaning the spring thickens on both the outer and innermost ends. The outer boss, also referred to as the Patek Philippe terminal curve, improves the isochronism of the balance in all positions by assuring concentric expansion and contraction of the balance spring. Conversely, the inner boss offsets positional changes of the center of gravity to assure the highest possible rate accuracy in vertical orientations. This means that the watch will not run slower or faster regardless of its position.
With the Spiromax balance spring, Patek Philippe declared that its watches can be regulated to a mean daily rate of -1 to +2 seconds – a remarkably feat for a mechanical watch, which usually runs two to three times that deviation (let’s not forget that shaving off precious seconds in accuracy is exponentially difficult the closer one gets to +/- 0, or perfect accuracry). Patek Philippe’s objective is to gradually introduce the new balance spring into its production, proof that Advanced Research is meant to benefit the brand’s entire output, and not just a limited run of watches.
The second innovation in the Aquanaut Travel Time Ref. 5650G is the time zone mechanism that relies on a complex, one-piece flexible spring – known as a compliant mechanism – in steel to set the second time zone forwards and backwards. In a standard Travel Time mechanism 37 parts were required, but the new mechanism needs only 12, with no gears or pivots. That eliminates the need for lubricants, since there is no friction, boosting its durability and reliability.
The crux of the new mechanism is an X-shaped piece of steel that is crafted to extreme tolerances: the individual leaf springs cross each other with a gap of only 150 microns. While the compliant mechanism is produced with the latest CNC milling machines, a necessity for such tolerances, it is made of conventional steel, just like any other part of the movement. This means the mechanism can be decorated like a traditional watch component.
The Aquanaut Travel Time Ref. 5650G has a white gold case and more notably, a skeletonized dial to show off the compliant mechanism for the second time, the very first Patek Philippe watch with an open dial. It’s a 500-piece limited edition.
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