In today’s highly competitive automotive industry, car manufacturers and suppliers are struggling to do things differently. Cost pressure, environmental regulations, and safety requirements are some of the factors that are pushing the limits of conventional car production. The FlexCrash project is addressing these challenges by exploring smarter, lighter and more efficient manufacturing approaches.
In this sense, aiming to be more competitive, bigger parts are produced, such as the so called giga-castings in aluminium and giga-stampings in steel. In some cases, these parts can be extremely large, representing a full scope of the Body in White (BIW), such as a full front or rear gigacasted unit. The key behind this trend is to integrate as many parts as possible, which will eventually lead to a reduction in the cycle time of the final assembly line at OEM, and hence in the cost.
This trend has more and more followers in the industry, but there are some limitations as well. These large components need to fulfil the same functions and requirements as the smaller parts replaced, resulting in a huge challenge for manufacturing feasibility. As a consequence, the tools required to manufacture them are also more complex, which can lead to higher tooling investments. Additionally, logistics is also a key point when it comes to giga-parts, being more difficult to handle and transport bulky parts.
Despite these limitations, giga-casting and giga-stamping are seen as transformative technologies with strong potential, helping to lead automotive transformation.
A hybrid manufacturing approach
While this trend pushes the limits of traditional manufacturing, the principles remain well-established. In this context, conventional manufacturing processes demonstrated to be powerful technologies to fulfil safety, comfort and cost requirements for decades. However, as part of this industry, we need to go a step further to adapt to the new context and to give solutions to the new requirements. In the FlexCrash project we are exploring new manufacturing technologies based on hybrid manufacturing. The approach combines conventional manufacturing technologies with Additive Manufacturing (AM) techniques, pursuing a reduction in cost, weight and environmental impact.
The conventional technologies involved in FlexCrash are aluminium extrusion and die-casting. The manufacturing process ends with Laser Metal Deposition (LMD) operations on the preformed surfaces.
This hybrid process aims to take advantage of the flexibility of LMD while keeping the production cost under control.
For instance, a significant limitation of the extrusion process is that the wall thickness of the section needs to be constant all along the profile. This is a clear constraint when designing for a crash performance since the strength required at each position of the profile depends on the desired force distribution and deformation kinematics. Hence, the thickness is usually fixed by the most demanded zone, while the remaining area is over-dimensioned.
To address this problem, in FlexCrash we are placing Added Value Functional Features (AVFF) on top of the extruded profiles. AVFF are small 3D geometric features that can be 3D-printed on top of the extruded surfaces. This way, the profile thickness can be reduced, while the weak areas are locally reinforced with additional material. Similarly, the die-casting process is limited by the tool opening direction and draft angles. In these parts, ribs are integrated into the casted part to locally increase the strength of the component. However, the direction (and hence the reinforcing capacity) of these ribs is usually constrained by the tool opening direction. LMD gives us new design possibilities, allowing local reinforcing in different directions.
Due to the increasing size and complexity of structural parts, developing robust and reliable simulations is fundamental to reduce costs in development and prototype phases.
For this purpose, we are not only performing complex simulations about the manufacturing processes (extrusion, Die Casting, LMD) during the FlexCrash demonstrator design, but also developing advanced virtual testing environments and state-of-the-art crash material cards.
Authors: Gestamp
