Araldite resins sound success for first composite trumpet

Swiss-based developer of precision composite parts has developed an instrument part it says will revolutionise the music industry.

Nägeli Swiss AG has developed the first carbon fibre trumpet bell using Araldite composite resins from Huntsman Advanced Materials.

A family owned SME, Nägeli Swiss AG worked alongside daCarbo AG, the initiator of the project, along with other partners, to create the instrument part, said to be the first made using made from carbon fibre reinforced plastic (CFRP).

The benefits of using carbon fibre compounds for wind instruments include the possibility to suppress vibrations in the tube that waste energy. Instrument-makers, engineers, acoustic designers and musicians involved in the project have worked together intensively to develop a trumpet and a trombone, which are said to be 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 fibres in the form of braided tapes are preformed and placed in a mould and Resin is injected into the closed and heated mould. A vacuum is applied, resin injected at high pressure and after the curing cycle, the finished part can be demoulded.

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-demouldable 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 reportedly 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 reportedly tested the daCarbo trumpet and currently the trumpet bell is in serial production in three different versions, to meet the individual requirements of players.