Inside BMW Leipzig - There is more to ‘i’ than Meets the Eye汽车专题
To the average man on the street, BMW’s ambitious ‘i’ sub-brand is represented by the all-electric i3 or the plug-in hybrid i8 that you see in BMW showrooms. Take a step behind the scenes and ‘i’ isn’t just about building a new generation of models to pique the interests of a niche audience. More than that, 'i' represents the company’s brave new endeavour into developing a new way of car construction that is just as environmentally friendly and sustainable as the cars themselves. This is the story of ‘i’ from its birthplace at BMW Leipzig.
Without a doubt one of the most talked about sports car on sale today is the i8, its blend of high-tech carbon-fibre construction, supercar looks, and space age technology, makes this the ‘Countach’ of our generation. It is just about the coolest, most eye-catching thing on four wheels right now. But eight years ago the ‘i’ sub-brand started out as nothing more than a think tank. The think tank’s goal was to envision mobility of the future, and what they ended up with was not only new clean energy-efficient models built from new lightweight materials, but a whole new ecosystem that stretches from materials sourced from environmentally friendly sources, and an entirely new production method that is more sustainable from an ecological, economical, and social perspective. To realise that vision, BMW needed a plant where they would be able to bring all these ideas and technology together.
Enter BMW’s Leipzig plant. Built in 2005, the plant is the company’s latest European plant and serves as the production hub for the 1-Series and 2-Series. From the moment we stepped into the main lobby of BMW Leipzig, it feels more like a modern office building than a production facility. The main building looks like a construct of the 21st century, rather than another unassuming factory block, boasting a cutting edge façade that is the handiwork of renowned Pritzker Prize winning architect Zaha Hadid. Body shells of 1-Series hatchbacks and 2-Series coupés are silently shuffled along automated lines from the body shop to the paint shop and to the final assembly over the heads of the offices in Leipzig, forging connection between employees and visitors that they are in the business of manufacturing cars, and as a statement of pride, that this is a place where some of Bavaria’s finest are being built.
While visitors of the plant would be greeted by the i8, there is no sign of any of the ‘i’ models being transported overhead, though it is to be expected. Since the i3 and i8 adopts a structure that is made entirely of carbon fibre, the first such models for the brand, an entirely new production system had to be built to facilitate the models’ production. And as such the ‘i’ models have their own manufacturing facility to manufacture its carbon-fibre parts, and assembly line at Leipzig. To see the birth of a new ‘i’ model we are ferried to a separate facility where the cars are being put together.
As you might already know, the ‘i’ vehicles all feature an occupant cell whose structure is made entirely out of carbon fibre, with metal and aluminium components used for the crash structure. This is all in the interests of saving weight, which also goes a long way in maximising the electric range of its drivetrains. The i3’s body for example, weighs in at an incredible 130kg, which would otherwise have tipped the scales at 300kg if it was made from conventional steel.
To produce all that carbon fibre for the production of the i3 and i8 is no small task either. The carbon fibre thread itself is produced at Moses Lake in the United States. From there massive looms of the black thread are shipped over to Wackersdorf in Germany to be weaved together into a fabric, and transported to Landshut and Leipzig where they are turned into the stiff lightweight panels used for production.
It might sound like a complicated and energy intensive process, but it isn’t. Project ‘i’ looked into the energy consumption and environmental impact of conventional vehicle production and sought to do away with aspects that were deemed high in energy and water consumption. For that, BMW chose Moses Lake to be the site of their joint venture carbon fibre manufacturing site with the SGL Group due to its location, as electricity demands for the plant is completely derived from hydroelectric power, and is touted as the most sustainable carbon fibre plant in the world.
While press forming metal panels does consume a huge amount of energy, BMW says that the manufacturing of carbon fibre panels does away with this energy intensive process. As a result of that, the electricity consumption of the whole ‘i’ production process can be met by four giant windmills located on site, which is capable of delivering a total annual energy output of 26GWh, effectively making the 'i' vehicles a truly zero-emissions car from birth.
To turn those carbon fibre textiles from Wackersdorf into usable carbon fibre panels, BMW adopts a method known as RTM (resin transfer moulding), where between five to 11 layers of carbon fibre fabric are laid out in a mould. The carbon fibre layers in the mould is then put into a vacuum, while heated epoxy resin is injected into it under high pressure . Under intense pressure, the layers are compressed and impregnated with resin to harden and form the shape of the specific panel. According to BMW, the whole process takes 8 minutes, which is a tiny fraction of the time taken to complete a normal RTM process that can take up to three hours, thus making it economically viable and competitive for production on a far higher scale than conventional means.
Excess carbon fibre from the production process are cut up and reused elsewhere such as the carbon fibre mesh that forms the rear seat shells of the i3 and roof lining of the ‘i’ models. In fact should any i3 or i8 meet an untimely fate, BMW says that up to 95 per cent of an ‘i’ vehicle can be recycled, with the battery being converted for use as an energy storage device.
The completed panels are then moved onto the assembly process. For those who are familiar with car production facilities, the first thing that you would notice is just how quiet it is. There is the usual ensemble of robotic arms on the production floor, gluing together the completed carbon-fibre body parts and panels, but since there is no welding or riveting involved in the production process, the assembly floor is far quieter. According to BMW this level of noise is part of the ‘i’ project’s goals in social sustainability as less noise equates to reduced levels of stress on the employees. It sounds all very altruistic, but is gluing the best way to go about assembling an entire car?
Many might have the impression that gluing an entire car is a sign of shoddy build quality, but this is carbon fibre panels that we are talking about, where the conventional welding processes can’t be applied. Similar to any Formula One car or high-end supercar, the carbon fibre structures in the i3 and i8 are bonded together, and it isn’t your usual method of patching parts together with super glue picked up from the nearby convenience store. It is much more advanced than that.
The sealer process used for the ‘i’ models represent a core innovation and is specifically developed for use in its assembly process. The sealant acts as both a material and integral part of the joining process, and is used uniformly throughout the car to bond all components material together, be it the car’s carbon-fibre structure or aluminium sub-frames.
The bonding process is completely automated using standard robotic arms found on conventional mainstream production lines, which applies a thin film of sealant with the precise thickness of 2mm. Once the parts are put together infrared lights are used to heat up the sealant to complete the bonding process, which BMW says, hardens faster than conventional sealers. Once bonded, the bonding strength is said to last a lifetime, even surpassing the expected lifespan of the car itself.
Not everything is automated however. Once the body shell has been put together, the installation of its cabin fixtures and attachment to the ‘Drive’ drivetrain module is still carried out manually on the final assembly process. Here the empty body shells are moved steadily along an assembly line as technicians on the assembly line fit in all the necessary components.
The wooden floor panelling fitted along the whole length of the assembly line is more than just adding a more inviting atmosphere for employees. BMW says the softer and flexible wooden surfaces lessens the load and stress on the legs of those working on the assembly line, yet another aspect of Project ‘i’s approach to social sustainability within their ranks.
Unlike conventional production processes the completed body shells aren’t put through a paint shop. In fact Leipzig doesn’t have a paint shop for the ‘i’ models at all, and it is all part of Project ‘i’ goal to reduce water consumption in the production process. Instead of painting the whole body, the i3 and i8 utilises painted thermoplastic panels that are attached to the bare structure. The i3 for instance have 17 panels that are fitted around the car, each of which are individually painted with water-based paint. Compared to standard paint shops, BMW says that this method of using thermoplastic panels results in a more compact facility, with a reduction of between 50 to 70 per cent in energy and water consumption. Furthermore, unlike conventional production process, the painted doors and panels are only fitted once at the final assembly process, thus removing the need for disassembling and reattaching the doors for the paint process.
Since the assembly of the ‘Life’ chassis module and ‘Drive’ powertrain modules are carried out in parallel on different lines, the production time of an ‘i’ model is considerably short, with the i3 taking as short as 16 hours to produce from start to finish by BMW’s own estimates. Due to the speed of assembly, production of the i3 and i8 are carried out on separate lines as the two models have different cycle times for each variant.
With this quick and efficient production cycle, BMW is able to produce around 100 i3s and 20 i8s a day, an impressive pace of production considering that the production of carbon fibre chassis is still considered a hugely time-consuming process amongst industry players. What’s more the beauty of this production process is highly flexible, allowing for shorter reaction times to changing customer demands.
As brilliant and revolutionary BMW’s i3 and i8 electric models are, the lesser known genius behind ‘i’ is the entire thinking behind it. Making a low-emission car is one thing, but ensuring that the process of producing such cars adds no further burden to the environment in the process is another endeavour all together.
Bringing together a production process that is able to run completely on renewable energy sources, consume 50 per cent less energy and up to 70 per cent less water, while cutting down 50 per cent on noise emissions, is an impressive feat in the world of car manufacturing. Its holistic approach that encompasses the pioneering of new materials, and developing new production concepts that is centred on the key element of sustainability.
Considering how the world is slowly waking up to our environmental impact on the world, the i3 and i8 might be more than just another pair of vehicles running on alternative powertrains, but the cusp of a new sustainable production concept for today and well into tomorrow.