Quartz fibre prepreg

To enable the manufacture of an intricately-shaped watch case for prestigious Swiss brand Richard Mille, North Thin Ply Technology (NTPT) has developed a unique thin ply quartz prepreg. The 52g/m2 material made its debut in the exclusive RM 27-02 Rafael Nadal watch first worn by the Spanish tennis player at the French Open in May 2015.

NTPT developed the TPT Quartz prepreg in collaboration with Saint-Gobain Quartz, which supplied its Quartzel fused quartz fibre reinforcement for the project, and Reichhold, which developed an ADVALITE hot melt, monomer-free vinyl hybrid resin for the matrix.

Richard Mille is renowned for pushing the boundaries of watchmaking with the use of new materials and designs and personally led the design and validation work. The company joined forces with NTPT four years ago to create the TPT Carbon carbon fibre prepreg, made using NTPT’s proprietary Thin Ply Technology.

The material had to show excellent strength to weight ratio, demonstrate that the material was non-allergenic, would not yellow in sunlight (UV) and was resistant to a range of chemicals that the watch could encounter. An unusual design driver was that the aesthetic properties required a white contamination-free composite.

Using its proprietary spread tow technology NTPT manufactured unidirectional (UD) quartz fibre prepreg tapes. These 45µm plies are composed of 600 layers of parallel quartz filaments. The UD tapes are transformed into 2D prepreg preforms using NTPT’s automated tape laying (ATL) equipment. Each layer is angled at 45° to the previous layer. To produce an interesting veined black and white appearance when the part is machined a layer of TPT Carbon prepreg is included between several plies of the quartz prepreg.

The preform is cured in an autoclave at a temperature of 120°C under 6 bar pressure to produce a densified composite block. The block is then machined into the watch components using CNC equipment at Richard Mille’s case factory.

Finally, each watch undergoes an acceptance campaign, which includes a series of 200G shocks, and chronometric function and water tightness testing. The resulting Richard Mille RM 27-02 wrist watch allies performance, architectural design and perfect finishing.

This 11-month project involved the close collaboration of the four companies – NTPT, Richard Mille, Reichhold and Saint-Gobain Quartz – and typifies the way in which NTPT works with customers to develop a material that answers their specific challenges.

Interestingly, it still tells the time.

Justin Cunningham

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