We’ve been focusing so much on the infinitely small that we didn’t see the infinitely large: the watchmaking paradigm shift. After three centuries striving for rigidity, the escapement is now all about flexibility and elasticity.
Some changes are so significant that we don’t even see them. At the turn of the century, one such change took place. It is not unique, not a single invention popularized by a single brand. Yet there it is, creeping along, still a little untamed but (to a certain extent) mastered. Think Patek Philippe, Girard-Perregaux, Ulysse Nardin, De Bethune, TAG Heuer. All have one thing in common: using the flexibility of the escapement.
Taking Mendeleïev by storm
Yet another article on the silicon escapement? No. Beyond physics, there is, as its name suggests, metaphysics, which is concerned with questions that go beyond matter. Because the real change to the escapement is not its material but its flexibility. The twenty-first century is the first in the history of watchmaking to offer supple and elastic escapements, within watches at least.
Because as the previous millennium was breathing its last, watchmakers were all striving for the same thing: hardness, impact resistance, absolute rigidity. Mendeleïev’s entire periodic table was machined in Vickers’ holy image: palladium, rhodium, lithium, carbon, as well as diamond, tantalum, steel, ceramic, sapphire, and all their children of varying legitimacy – NTPT carbon, TPT quartz, Magic Gold, Hublonium, LITAL, and others. And then came a very special case: Si14 or silicon.
Hard as oak or supple as a reed?
Like most technological breakthroughs, the notion of flexibility was preceded by a break with traditional thought. Although the trend was to provide protection (against impacts, temperature variations, magnetic fields: think Master Co-Axial, METAS certification), the new wave concentrated on performance, precision, and energy efficiency.
This new elastic wave didn’t just appear out of the blue. Many watch components already utilize the flexibility of their materials. It was the basis for the barrel spring in the fifteenth century. And let’s not forget the lever springs of calendars, chimes and all sorts of complications, including the helical blade of 400-day pendulums.
The silicon & nanotechnology duo
So the idea is no longer (just) to be forearmed, but to cease wasting energy. The enemy has a name: the escapement. It loses 60% of its energy with each oscillation. Why? Due to the three stages of oscillate/stop/restart. A mechanical aberration that only watchmaking is prepared to accept. Imagine a car that would have to shift to neutral and stop before changing gears! Unthinkable? Absolutely. But in watchmaking, it is standard practice!
As habits are hard to break, the first uses of silicon followed this same pattern of thought. Watchmakers looked to it to provide what they had always sought: hardness. “When we began to combine it with nanotechnology, a whole new field opened up,” says the watchmaking development department at Sowind.
“It went further when we were able to use varying thicknesses of silicon. And lithography fabrication (LIGA DRIE) makes it possible to apply new geometries,” continues Marc-André Glassey from Sigatec. In concrete terms, we could work on a sliver with a rigid base and a thinner and therefore more flexible upper part. Consequently, we could predict the sliver’s specific point of inflection and its torque coefficient.
Waiting for IsoSpring
The Constant Escapement by Girard-Perregaux and the TAG Heuer Carrera Mikrogirder would apply this principle. The Anchor Tourbillon and Escapement by Ulysse Nardin are along the same lines and embody what is probably the epitome of tourbillon escapement’s possibilities, thanks to the flexibility of silicon.
Patek Philippe has chartered a new course: IsoSpring. The piece is not yet readily available to view, but we already know its main feature: a unidirectional, continuous oscillator. “Our prototype weighs four kilograms at the moment, but we’re working on miniaturizing it to fit it in a wristwatch,” explains Simon Henein, holder of the Patek Philippe Chair.
This IsoSpring also utilizes the elasticity of silicon. Its inventor speaks of a “flexible guide” but, once again, it is the elastic properties of the silicon spring blades that are the issue. IsoSpring has managed to get rid of the first of the three-stage oscillate/stop/restart process, the oscillation, which is the “ticking” sound. That just leaves the stop/restart stages to deal with. We can just imagine what the focus of work will be in the 21st century.