RM 74-01
Uniquely appealing and technically complex
The RM 74-01 and RM 74-02 In-House Automatic Tourbillons offer two new versions of the fully in-house automatic tourbillon calibre. These two striking models, both with the same ultra-skeletonised heart, are distinguished by the materials used for their cases as well as by their aesthetics, making them fraternal twins with unique personalities.
RM 74-01 Automatic Winding Tourbillon
IN-HOUSE CALIBRE CRMT6
Skeletonised automatic-winding tourbillon movement with hours, minutes and variable-geometry rotor.
POWER RESERVE
Around 50 hours (± 10%)
BASEPLATE AND BRIDGES MADE OF GRADE 5 TITANIUM
The baseplate and bridges of the RM 74-01 are crafted of 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% aluminium and 4% vanadium. This combination further increases the material’s mechanical properties, which explains its frequent use in the aerospace, aeronautics and automotive industries.
The skeletonised baseplate and bridges were subjected to intensive and complete validation tests to optimise their resistance capacities.
FREE-SPRUNG BALANCE WITH VARIABLE INERTIA
This type of balance wheel represents the ultimate in innovation. It guarantees greater reliability when subjected to shocks and during movement assembly or disassembly, hence better chronometric results over time.
The regulator index is eliminated, and a more accurate and repeatable calibration is possible thanks to 4 small, adjustable weights located directly on the balance.
VARIABLE-GEOMETRY ROTOR
The RM 74-01 uses variable geometry to optimise the rotor’s winding motion.
Rotor specifications:
• Heavy outside edge and heavy edge ring in 18K white gold
• Weight segment in platinum
• Automatic OneWay® winding system in ceramic with ball bearings
• Bidirectional winding system
This variable-geometry rotor has been incorporated within the in-house CRMT6 calibre, making it possible to set the rotor according to the owner’s activity level.
The setting is modified by adjusting the two moveable weights into the correct position and fixing them in place with spline screws. The inertia of the movement is increased when the two weights are closer together; the barrel then rewinds more quickly. If the weights are positioned at the extremities of the rotor, the inertia is decreased and the barrel winds more slowly.
MOVEMENT CHARACTERISTICS
- Movement dimensions: 30.70 x 23.70 mm
- Thickness: 6.20 mm
- Number of jewels: 23
- Balance: CuBe, 4 arms, 4 setting weights, moment of inertia of 7.5 mg.cm2, 50º angle of lift
- Frequency: 28,800 vph (4 Hz)
- Balance spring: AK 3
- Shock protection: INCABLOC 908.22.211.100 (transparent)
CASE IN GREY CERMET
A material exclusive in watchmaking to Richard Mille, grey Cermet combines the lightness of titanium with the hardness of a ceramic. It consists of a metallic zirconium matrix associated with high-performance ceramic that gives the material its singular grey colour.
The production process is no less extreme than the material itself. Heating and forming such different materials together at high temperatures without adulterating their respective quali¬ties and achieving a homogenous material is no mean feat, and one rendered all the more difficult as the composition eschews the nickel and cobalt generally used in this family of hard materials for a material that is fully REACH compliant.
After years of development in specialised laboratories, Richard Mille and the Groupe IMI have succeeded in eliminating these unwanted binders, conserving only the desirable materials thanks to an innovative process that combines conventional hot-stamping associated with a series of bursts of high-voltage electrical current that augment the kinetics of the sintering. The technique is known as flash sintering.
Materials of a similar composition are employed in ballistic protections and in aerospace for shuttle re-entry components, exterior fuselage pieces and in the brakes on competition vehicles. Cermet has a mass to volume ratio of 4.1 g/cm3 and a hardness of 2,360 Vickers, comparable to other high-performance ceramics, making it eminently suitable for use in bezels, an area highly vulnerable to scratches, while ensuring that entire assembly is light in weight. These bezels are affixed to a caseband made of grade 5 titanium, which also contributes to lowering total mass.
The tripartite case is water resistant to 50 metres, ensured by 2 Nitrile O-ring seals. The case is assembled with 20 grade 5 titanium spline screws and abrasion-resistant washers in 316 L stainless steel.
Finishing
Movement
• Hand-polished anglage
• Hand-polished stepped bevelling
• Microblasted milled section
• Microblasted sinks
• PVD treatment for the baseplate and bridges
Steel parts
• Satin-finished surfaces
• Hand-polished anglage
• Hand-polished sinks
• Burnished sections
Wheels
• Diamond-polished sinks
• Circular decorations on the front surfaces
• Rhodium plating (before cutting the teeth)
• Minimal corrections applied to the wheels in order to preserve geometry and performance
Other features
FAST-ROTATING BARREL (5 hours per revolution instead of 7.5 hours)
This type of barrel provides the following advantages:
- 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.
GEAR TEETH PROFILE
The entire going train of the watch, the primary transmitter of power through the movement, utilises a special profile for the teeth of the wheels. Developed specifically for Richard Mille’s in-house calibres, the wheels employ a 20° pressure angle. This system equalises any discrepancies that might arise between the centres of each wheel, for instance, during thermal changes and normal use, and promotes excellent torque transmission to the balance wheel, thus supporting excellent chronometric characteristics.
SPLINE SCREWS IN GRADE 5 TITANIUM FOR THE BRIDGES AND CASE
This permits better control of the torque applied to screws during assembly. These screws are therefore unaffected by physical manipulation during assembly or disassembly and age well.