Vulkalloy® Ni, an innovative metal alloy for watchmaking applications. The use case of the Swiss lever escapement wheel.
Context and issues
The power reserve of a mechanical watch is strongly limited by the energy losses due to friction and shocks localised at the level of the gear train and the regulator oscillator. It is also affected by the moments of inertia of the components and the kinetic energy required to drive them. In a watch movement, most of the friction losses are located at the level of the wheel pivots and the anchor, while the shock losses are mainly located at the level of the interfaces between the anchor, the escape wheel and the oscillator. Eliminating this friction and reducing the losses during these shocks makes it possible to reduce the energy required to drive the entire gear train and the oscillators. The materials commonly used are brass for the gear train and special steels for the escapement wheel, the anchor and the regulator compensation spring.
The Vulkalloy® Nickel base alloy is an answer to these challenges because of its excellent mechanical and tribological properties, which are far superior to existing solutions. It is particularly suitable for the production of flexible mechanisms that are subject to high mechanical and frictional loads. It allows the production of high precision parts with excellent surface finishes. It is also non-magnetic and has very good corrosion resistance !
Please find out the detailed characteritics of the Vulkalloy(®) Ni by dowloading the material leaflet
The Vulkalloy® Ni exhaust wheel compared to Durnico
it is possible to report gains in moment of inertia and power due to the high yield strength of Vulkalloy® Ni base. Indeed, Vulkalloy® Ni base has a 40% higher yield strength than Durnico (2800 Mpa instead of 2000 Mpa), which makes it possible to lighten the parts and thus reduce the moment of inertia (J : ½ MR²) by about 40%. The drive kinetic energy (½ *J*V²) can, therefore, be reduced by the same amount, which opens the way to a reduction in the power required for the drive and/or an increase in the operating frequencies of the assembly.
Vulkalloy® Ni increases the available power reserve of a watch movement as well as its performance, reliability and durability thanks to its exceptional mechanical and functional properties.
In addition, the use of Vulkalloy® Ni base allows for energy savings in the frictional contacts between the wheel and the anchor due to its very low friction coefficient. Indeed, Vulkalloy Ni has a coefficient of friction of about 0.06 in lubricated conditions, which is about two times lower than that of other metals used in watch movements. The power dissipation, which is directly proportional to the friction coefficient (P = Pt*Hv*Cf), is reduced by 50% compared to existing materials. In addition, the wear rate of Vulkalloy® based on Ni is also significantly lower than current metal solutions.
Vulkam, an innovative metallurgy company serving the watch industry
Vulkam is an SME specialised in Amorphous Metal Alloys which has developed a range of new metals with unrivalled properties, The Vulkalloys®. Its technology is based on changing the atomic organisation of metals to fundamentally change the mechanical properties of the parts produced. Vulkalloys® parts are produced by a unique proprietary process. It is specifically developed for these materials and is fully adapted to miniature components (a few tenths of a mm to a few cm). Its two patented steps allow the production of parts with variable shapes, precision and excellent surface finish, as well as the optimisation of their geometries.
If you would like to know more about the watchmaking applications of Vulkalloy® Ni after reading this use case, please contact us: info@vulkam.com
