Richard Mille RM 50-02 ACJ Tourbillon Split Seconds Chronograph
Limited edition: 30 pieces in Titanium-Aluminum.
Calibre RM50-02 : Manual winding tourbillon movement with hours, minutes, split-seconds chronograph with running seconds, 60-minute totaliser and power reserve, torque and function indicators.
Dimensions : 50.10 x 42.70 x 16.50 mm.
Main featuresPower reserve:
Circa 70 hours (±10%), displayed on a numeric scale near 11 o’clock.Skeletonised titanium baseplate
The baseplate has been finished in grade 5 titanium, a biocompatible, highly corrosion-resistant and remarkably rigid alloy, which enables the gear train to function effortlessly. The alloy is 90% grade 5 titanium, 6% aluminum and 4% vanadium. This combination further increases its mechanical properties, which explains its frequent use in the aerospace, aeronautical and automobile industries.
The baseplate of the calibre RM50-02 has been optimised to achieve an extreme weight/resistance ratio.Bridges made in grade 5 titanium and stainless steel
The bridges of the calibre RM50-02 are made of grade 5 titanium. To give more depth to the calibre, some bridges are made of stainless steel and given a golden appearance by treatment with aircraft coatings.Split seconds mechanism with improved performance
One of the new characteristics developed for the split seconds tourbillon RM 50-02 is the virtually complete elimination of initial jumping in the chronograph seconds hand. Moreover, the development of a new generation of split seconds components meant that energy consumption of this function could be lowered by approximately 50 % through the reduction of friction within the movement, and the elimination of the inertial jumping of the chronograph’s hands during stopping and starting. This was achieved by research focused on the working of the split seconds’ arms. Operation:
by depressing the pusher on the right at 4 o’clock, the user can stop the split seconds hand in order to read an intermediate time while the chronograph is engaged. Pressing the pusher again allows the split seconds hand to rejoin the chronograph, ready for the next measurement.Torque indicator
This indicator supplies information about the mainspring’s tension, thus permitting the optimisation of the chronometric functioning of the movement. Below 53 dNmm, the spring is considered to be too slack, while above 65 dNmm, the excessive spring tension can adversely affect the mechanism’s operation, or else actually endanger it. (These indications appear on the numerical zone near 2 o’clock).Function indicator
In a manner similar to a car’s gearbox, the function indicator allows one to see the winding, neutral and hand setting positions as the crown is pulled out. Each position is indicated via a hand at 4 o’clock displaying the following functions: W
(Winding) – N
(Neutral) – H
(Hands).Balance wheel with variable inertia
This type of balance wheel guarantees greater reliability when subjected to shocks and also during assembly and dismantling of the movement, thus achieving better chronometric results over time. The index is eliminated, thereby allowing a more precise and repeatable adjustment using 4 setting screws.Fast rotating barrel
(6 hours per revolution instead of 7.5 hours)
This type of barrel provides the following advantages:
Barrel pawl with progressive recoil
- The phenomenon of periodic internal mainspring adhesion is significantly diminished, thereby increasing performance,
- Provision of an excellent mainspring delta curve with an ideal power reserve/performance and regularity ratio.
This device permits an appreciable winding gain (circa 20 %), especially during the start of winding. It also aids in the even distribution of the mainspring’s internal tension.Winding barrel teeth and third-wheel pinion with central involute profile
The wheel with a central developing profile and a pressure angle of 20° promotes rolling movement more effectively, compensates differences between centers, ensures excellent torque transmission and a distinct improvement in performance.Modular time setting mechanism fitted against the case back
Provides the following advantages for longevity and maintenance:
Spline screws in grade 5 titanium for the bridges
- Since the component is mounted outside of the movement, the time setting assembly can be changed without affecting the integrity of the baseplate in the event of a possible defect or during maintenance,
- The mounting and dismantling of this module from the back will not require the removal of the hands and the dial.
This permits better control of the torque applied to the screws during assembly. These screws are therefore unaffected by physical manipulation during assembly or disassembly and age well.Other features
Case in titanium-aluminum
- Movement dimensions: 32.00 mm x 30.40 mm
- Thickness: 7.87 mm
- ourbillon diameter: 12.30 mm
- Balance wheel diameter: 10 mm
- Number of jewels: 37
- Balance wheel: GLUCYDUR, with 2 arms and 4 setting screws
- Moment of inertia 10 mg.cm², angle of lift 53°
- requency: 21,600 vph (3 Hz)
- Balance spring: Elinvar by Nivarox®
- Shock protection: KIF Elastor KE 160 B28
- Barrel shaft in nickel-free Chronifer (DIN x 46 Cr 13 + S), with the following characteristics: stainless – antimagnetic – suitable for tempering
The design and execution of the watch demonstrates a complete conceptual approach to the movement, case and dial. As a result, everything has been constructed according to an extremely rigorous specification, in the manner of the analytical engineering methods used in the design of Formula 1 racing cars where the chassis and the engine are developed in complete harmony. For example, a casing ring is no longer used and the movement is mounted on chassis mounting rubbers (ISO SW) fixed by 4 titanium screws. Features such as these are evidence of uncompromising workmanship.
The case of the RM 50-02 is made in Titanium-Aluminum (TiAl). This intermetallic alloy has characteristics that stand between metals and ceramics, with physical properties characteristic of a metal with mechanical properties resembling ceramic. It exhibits an extreme rigidity and is much lighter than classical titanium alloys. This Titanium-Aluminum is the same alloy as that used in the Airbus for its jet turbine blades, which must function safely under the convergence of high temperatures and high fields of pressure, thus requiring a very strong and highly stress resistant material.
The main difficulty of preparing TiAl comes from the very large difference of the melting points of its two major components titanium and aluminum. Successive heating in a plasma oven ensures good homogeneity of the TiAl ingots used to machine the case of the RM 50-02.
The bezel in Titanium-Aluminum has been created with second bezel in ATZ white ceramic. This high quality ceramic is based on aluminum oxide powder injected at a pressure of 2,000 bar. This high-pressure injection increases rigidity by 20-30% and reduces the material's porosity to an absolute minimum.
ATZ has the reputation of being a particularly scratch-resistant material (1,400 Vickers), and possessing an unchangeable color. After diamond, it is one of the hardest materials in the world. A long and difficult machining process using diamond tools is necessary to create the complex form of this bezel, which is given a final matt surface finish. These qualities make it the ideal material for the front of the watch, an area highly exposed to impact and abrasion.
The case is assembled with 20 Torq set® screws in grade 5 titanium and abrasion resistant washers in 316L stainless steel. Torq set® screws for the case
Torq-set® screws utilise a waved slot pattern where each arm of the slot is also offset from its neighbor. These types of screws are used in aerospace applications where the applied torque must be exactingly executed, and for the security they offer against tampering. This configuration provides greater strength within the screw than a cruciform design, with an excellent transfer of torque. The shape also insures perfect interlocking of driver and bit providing fast removal even if the screw has corroded, seized or frozen.Torque limiting crown
This added security system prevents accidental over-winding of the watch, the result of which can cause possible damage to the winding stem or the application of extreme pressure on the barrel spring.Interior flanges
(outer and inner)
In metal, green painted with hour index points filled with an approved luminescent material.Dial
In sapphire (thickness: 0.40 mm) with anti-glare coating (both sides), protected by 8 silicon clamps.Bezel and case back
- Bezel side: in sapphire (1,800 Vickers) with anti-glare coating (on both sides).
- Thickness: 1.60 mm
- Case back: in sapphire with anti-glare coating (on both sides)
- Thickness: 1.20 mm
- Hand-polished bevelling
- Hand-polished locking-sections
- Microblasted milled sections
- Lapped and polished contact points
- Burnished pivots
- Wire-drawn and microblasted surfaces
- Hand-polished bevelling
- Concave chamfering with a diamond tool
- Circular-decorated faces
- Gilding (before cutting the teeth)
- Minimal corrections to preserve the geometry of the wheels and their performance