BMW’s carbon fibre manufacturing processes attest to its pedigree as a leading automotive manufacturer. We see how this features in the new flagship 7 Series luxury limousine.
When BMW launched the i3 and i8 back in 2013 and 2014 respectively, it proved to be watershed moments for a brand that was already synonymous with luxury and driving performance. With the BMW i cars, the manufacturer was able to exhibit its technical prowess through its processes.
RAISING THE BAR
Going a step further with the use of carbon fibre reinforced plastics (CFRP) that first featured in the Life Module in the i3 and i8 electric cars, BMW EfficientLightweight involves using this material to create a carbon core in the new 7 Series luxury limousine. However, in the case of the BMW flagship, other considerations such as comfort, safety, luxuriousness of the interior, quietness, driving dynamics and efficiency became as important as shaving weight to achieve the best range from the BMW i car’s electric motor. Central to this is CFRP. Lightweight and exceptionally strong – compared to steel, it’s five times stronger but 50 per cent lighter! – CFRP not only helps reduce vehicle weight, its structural rigidity also helps enhance safety (in the event of a collision) and driving dynamics. Little wonder then that the material is in jets and Formula One race cars. While carbon fibre can be tricky and expensive to work with, BMW has been able to maximise the use of the material on an industrial scale with minimal wastage, as demonstrated in the i8 sports car. With that manufacturing experience with CFRP and the knowledge of a “whole car” approach to lightweight engineering, BMW’s Carbon Core concept features a very advanced and intelligent material mix involving CFRP, steel and aluminium – a first for a car in this segment.
‘MAGIC’ IN THE BUILD
In much of the 7 Series, lightweight materials now feature more extensively in both major and minor components in and around the car. Specifically, the use of CFRP optimises the body’s properties and is most effective in parts that have to withstand high forces. In total, 16 pieces of CFRP are built into the automobile’s structure, using four main techniques that help engineers achieve their objectives. In areas like the roof rails, this material has been used for enforcement through a process called twisting, where strands of carbon are woven and fixed with resin to build up a desired part in the car’s frame with little wastage. In areas that require the strengthening properties of CFRP, such as in reinforcing the B-pillars, carbon fibre steel hybrids are created by pressing and gluing CFRP with a high-strength steel panel to meld the two materials together. In larger sections of the car, sheets of CFRP are laid and bonded together through a process called laying. Elsewhere, areas like the upper portion of the vehicle’s boot and C-pillars make use of a sustainable process with recycled CFRP. Here, leftover cuttings are shaped to fit and held together with resin.
As a result of this mixed-materials approach, the 7 Series is not only a significant 130kg lighter, it has also been made stronger and more rigid around the passenger cell for enhanced safety and comfort. Passengers sit more snugly within the tranquil and luxurious cabin, with little interruptions like noise and imperfections on the road. For the driver, the availability of a new electric-hybrid drivetrain in the 740e plug-in hybrid makes performance far more efficient. The improved torsional rigidity and 50:50 weight balance in the new model also translates to improved handling and dynamism that is immediately noticeable the moment one takes the wheel. It is with these state-of-the art processes and a cohesive intelligent design of the entire car that BMW has been able to showcase its Efficient Lightweight philosophy, with the new 7 Series as its standard bearer.
EFFICIENTLIGHTWEIGHT AT WORK
Scan the QR code to find out more about what makes up the carbon core of the 7 Series and how BMW’s EfficientLightweight philosophy has been applied in the car.