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A trumpet bell in composite

News International-French

19 May 2015

Araldite composite resins from Huntsman Advanced Materials have been used by Nägeli Swiss AG to develop a trumpet bell that is set to revolutionise the music industry.

A family owned SME, Nägeli Swiss AG is an established innovator in the processing of advanced materials into high quality products, manufacturing custom metal and composite parts and developing components made of carbon fiber or glass fiber.

With different manufacturing processes such as autoclave-free prepreg processing, RTM or thermoforming, Nägeli Swiss AG manufactures prototypes as well as serial parts s and has been involved in projects in an array of diverse industries, including Aeronautics, Formula 1 and Space.


Bringing new technologies to musical instruments
In co-operation with daCarbo AG, the initiator of the project, Musik Spiri in Winterthur, the Technical University of Rapperswil and the Institute of Music Acoustics of the University of Vienna, Nägeli Swiss AG were tasked to be the first to develop a trumpet bell made from carbon fiber re-inforced plastic (CFRP).

By making wind instruments from carbon fiber compounds, it is possible to suppress vibrations in the tube that waste energy. Instrument-makers, engineers, acoustic designers and musicians have worked together intensively to develop a trumpet and a trombone which are easier to play yet produce a warm and rounded sound.

Specific challenges
To ensure the surface of the trumpet bell met the high quality finish required on the inner side of the bell (influence to the sound) as well as the outside (aesthetics), the viscosity behaviour of the resin system had to be suitable for injection under temperature and the curing cycle of the resin had to take into account that a melting core is used so that the temperature range is limited.

The trumpet bell is made using RTM (Resin Transfer Moulding) technology.

Dry fibers in the form of braided tapes are preformed and placed in a mold and Resin is injected into the closed and heated mold.  A vacuum is applied, resin injected at high pressure and after the curing cycle, the finished part can be demolded.

Another challenge lay in the geometry of the bell, which is connected with a U-bend to the metal valve engine. This geometry results in a non-demoldable core, which is why an appropriate process for melting core technology has to be developed.

Project Success
The great advantage of the daCarbo-instruments lies in the measurable and noticeable lower blowing energy that is necessary for the playing of a sound. Due to the high stiffness of the instrument panel and the good damping properties of composite materials, the percentage of non-audible vibrations of the bell is reduced, therefore increasing the reflection component of the sound. Blind tests have shown that daCarbo-instruments correspond to the tone characteristic of the typical conventional trumpet sound and are readily accepted in professional orchestras.

However, the daCarbo Trumpet offers a number of other advantages which are justified by the CFRP material. Firstly, the specific geometry leads to an exceptionally clear tone. The production, in contrast to the manual production of brass instruments, is largely automated, providing a constant quality, corrosion problems from condensation are non-existent inside the instrument and ultimately the harmonically rich character of the high tone register leads to a warm and open sound.  Famous musicians like Arturo Sandoval, Jon Barnes or Roy Hargrove have tested the daCarbo trumpet and currently the trumpet bell is in serial production in three different versions, to meet the individual requirements of players.

Nägeli Swiss AG are serviced by Huntsman’s distributor in Switzerland, Bodo Möller Chemie.  A  leading supplier of speciality chemicals and partner for high performance adhesives, bonding systems, epoxy resin adhesives, potting and casting resins, Bodo Möller provides Nägeli with a local and customised service resulting in profitable added value.

Niklaus Nägeli, Member of the Board of Nägeli Swiss AG, commented  “We chose Huntsman products because they bring many years experience in resin systems to the table.  The production rate requires a fast curing system and Bodo Möller quickly identified the right system for the job.  It was crucial to be the first player in the market and we met our target date thanks to this joint co-operation.”