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Process driven design
Chassis clamps are traditionally made in aluminum by traditional subtractive tooling as cutting and milling. When we tried to innovate the chassis clamping method, immediately it was clear that the entire process should be considered in the redesign, instead of one physical component. How many types of clamps were used before? Were they all mandatory? Which strength the clamps must have? And which stiffness? Innovative production processes could be technically and economically sustainable?
Chassis assembly lines
In the "body in white" (BIW) assembly lines, the car flanks are welded to the platform and to the roof. Here the chassis parts are held by special clamps which apply compressive load and keep the elements inside the tolerance before the spot-welding process.
The clamps are complex components since they must replicate the sinuous shape of the chassis at the contact point. These fastening elements, then, change with the car model and represent an important cost for the line setup.
Categories harmonization
After the detailed categorization of all the clamps used in the factory line, all the found geometries and typologies (around 50) have been reduced to only 3 fundamental families.
Topology optimization
Then, for each family we identified the optimized shape for the clamps fabrication with an additive manufacturing process.
Shape morphing by parametric CAD
The process engineers must have a simple and effective tool to manage the geometry variability of the chassis clamps. The shape-morphing of the clamp is provided by the parametric CAD interface working on each family group. The file output is ready for 3D printing.
Carbon fibers 3D printing
The best process for in-line clamps building is identified with the continuous filament fabrication (CFF). Starting from the traditional fused deposition modeling (FDM), a carbon fiber is extruded together with the polymer filament. The result is a composite with orientated fibers that provide the directional strengths imposed in the project. In this way, the component stiffness is determined by the fibers pattern more than the carbon percentage. The final structural properties are similar to those of the original aluminum version.
Costs analysis
The shape-morphing design and fabrication of clamps is changing the old line setup. The technical feasibility of the new method is accompanied by relevant economic savings.
In the first scenario where the production is outsourced to contractors, the overall saving is calculated as 42% of the original cost. In case of self-production, after first investment amortization, the overall saving is 83%.
Header photo by Birmingham Museums Trust
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