The first driver test vehicle (FET) drives. We could not have imagined that the test drives would fulfill all expectations. Feeling the safe driving dynamics of this driving machine sticking to the asphalt was an enriching experience. The frame – the so-called BIW, Body-in-White, which is black in our case – of the first TWIKE 5 FET was previously only provisionally screwed and stapled.
The next visible step in the development is to replace the BIW with a glued and riveted version. The adhesive bond has established itself in the automotive industry and is considered to be at least equivalent. The adhesive seals on its contact surfaces at the same time and the often weakening heat input from the welding process is also eliminated. The findings from the construction of the first model flowed back into the CAD model in every detail and were used again in the procurement process for the first three or more prototypes.
The black coating on the surface immediately after forming (laser cutting, punching, bending, edging) is visually striking. The aluminium components are passivated by anodizing on their surface and are thus prepared for the bonding process as well as protected for later road use.
Until now, brackets made of sheet metal have been replaced by solid and precisely milled aluminum nodes (see illustration, example of BIW node at the rear left for mounting the trailing arms). These nodes allow optimum load transfer of all driving forces to the frame structure and can still be machined in the selected size on small CNC machines. In the BIW production process, they represent reference components for maintaining dimensional accuracy.
Although there was a delay in the delivery of the aluminium sheets, the individual sheets and other aluminium components of the frame have now been anodized black and the assembly of the new body-in-black* has begun. The dimensional accuracy of the entire assembly is ensured by aligned holes, which are drilled into the sheets with high precision using a laser process. In addition, the successively larger sub-assemblies are glued and riveted together on a precision table so that the specified tolerances can be maintained, especially for the connections of the chassis components.
Once the vehicle frame has been joined, the current driving test vehicle is dismantled and all near-standard add-on parts are moved to the new frame. After this update, all loads to be expected in later operation are introduced with more demanding driving maneuvers, thus ensuring suitability. You can find out more about the resulting Black FET (rider test carrier) and the driving tests carried out with it in the following articles.
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* The so-called BIW, Body in White, which is black here.
Article updated on 05.09.2024
