Thermoforming of Auto Body Components
Fibre-reinforced composite materials are creating competition for their steel counterparts. A research project is currently being conducted to determine whether such parts are suitable from an economic standpoint for moderate-sized production runs in the automotive industry.
Lotus Engineering and Jacob Composite GmbH are cooperating in a joint research project to determine whether composite materials are suitable for automotive production from an economic standpoint. The objective of the “Ecolite Project” (“Efficient Composites – Lightweight and Thermoformed”) is to manufacture from composite materials a large auto body component from a vehicle that is produced in moderate quantities.
The Ecolite body components are produced by thermoforming semi-finished starting materials. Depending on the thermal and mechanical requirements, different glass fibre-reinforced thermoplastics such as PA, PBT and PS are employed. The impregnation and consolidation of the semi-finished starting materials play an important role in this regard.
This production method involves considerably lower investment than that for metal stamping dies and permits shorter cycle times than previous processing techniques based on thermosetting composite materials. Moreover, the omposite materials can be recycled and offer significant potential for weight savings.
Investigations using a front-end module
In the first phase of the project, the front-end module of a family car that achieved a high ranking in the Euro-NCAP crash test is being converted to the composite technology. The team is selecting the relevant materials and processes for the components of the crash structure for further development. The front-end module will then be subjected to a series of tests to compare the performance of this structure to that of its steel predecessor. At the same time, the suitability for mass production is being investigated.
In the second phase, the project will be extended to the remaining parts of the vehicle’s body. Lotus Engineering and Jacob Composite plan to present a complete composite auto body. Simultaneously, the economic viability for production runs of 30 000 to 50 000 units per year will be scrutinized. With additional materials development and new manufacturing techniques, it is expected that the technology can also be made economically attractive for higher production volumes.
In conjunction with advanced CAE techniques, especially for simulation of crash behaviour, sufficient data can be obtained quickly enough to permit rapid modification of the part design. The tooling is designed in a similar manner with the aid of a unique thermoforming simulation program. This contributes to shorter lead times and reduced investment.