Recently under the rubric of the Geneva Motor Show 2015, I mentioned the Light Cocoon concept car produced by the consultancy EDAG. This work highlighted the possibilities of additive manufacturing methods. Does it have a meaningful place in the future of car manufacture?
First, let´s find out a bit more about additive manufacturing. In contrast with standard mass production, additive production relies on building up material layer by layer using lasers to activate and bind particles together to the required shape. Lasers follow a path through a mass of granules and cause selected ones to fuse. The path is defined by a mathematical model generated using CAD programmes. Other additive methods use extrusions of hot plastic laid down in layers. Again, the layers are defined by CAD data. The key thing is that material is addded and not removed. (Sculpture using stone is subtractive manufacturing, so is wood turning.) In automotive production the methods used to make thing usually involve stamping where a flat sheet of metal is pressed into the required shape using a specially made one off tool. In moulding processes a liquid is introduced to an empty form and takes up the shape of the tool. In both cases the CAD data is mediated by costly forms or dies which need to be milled slowly from tough materials. These are usually finished (polished) by hand to
an acceptable level of smoothness. As the designer David Pye noted in his lovely book The Art Aesthetics of Craftsmanship, the designer´s intention is mediated by the craftsman. An identical dimensioned drawing could be finished to a variety of standards depending on the skill of the craftsman. In additive technology this “craftsmanship of risk” is replaced by the laser. The quality of the surface finish is controlled by the granularity of the material chosen.
The advantages of additive technology is that the unit cost of the first item produced is less than that for the same part produced using forming or moulding. It might cost several hundred thousand euros to make a tool so the first item made will cost that plus the material. An additively made part will cost dramatically less: a rapid prototyping machine can be put on your desk for a thousand euros, sometimes less. The disadvantage is speed. While a press can stamp a sheet of steel in a few seconds, with a cycle time between parts of a few minutes perhaps, an additively made part can take a few hours depending on the size of the item and the exact machine used. It would not be feasible to supply the Ford Focus production line with body panels made additively.
Other advantages are that complex parts that forming can´t achieve can be managed by additive technology and the waste volumes can be reduced.
However, not every car needs to be made in the kind of volumes required by VW, Renault or Kia, for example. And conceivably, not all parts need to be made of the usual materials we associate with series production.
EDAG have been exploring two alternative approaches to car engineering recently. The 2014 EDAG Genesis used a biomorphic principles and additive construction to shape the elements of a vehicle safety cell. The individual elements have a sandwich structure. When locked together they form a shell that is remarkably strong yet light. It mimics the economy of natural forms such as a the turtle´s exoskeleton and the branching structure of trees. Energy in nature is in short supply and as a result, animal and plant forms often demonstrate a high degree of efficiency in the construction of load-bearing structures. Bird´s wings would be a classic example as is the very familiar bird´s egg (itself additively produced with the data encoded in DNA and mediated by cell metabolic processes).
What can be learned from this is that biomorphic principles can be used to design crash structures and load bearing structures using a lot less material. The nature of the construction is that the material is deployed only where loads are expected to be channelled. In EDAG´s phrase, the design is load specific. In addition EDAG have used weldable plastics and metals where parts needed to be fixed in place.
EDAG drew up a road map for the extended use of additive technology in collaboration with materials and prototyping specialists from German universities. In the short-term, small items of trim could be manufactured sufficiently quickly. In a decade major pieces of trim could be made, presumably with secondary treatments to ensure good enough surface quality. In 2035 EDAG predicts large sub-units of the chassis could be made. The experience learned thereafter would allow the possibility of an entire floorpan to be manufactured. This item is especially tempting as it is a complex item already made using a lot of smaller parts that have to be pressed and welded. This road map presumes the use of five different types of additive engineering. It also assumes a 100 to 1000 fold increase in the speeds of the processes. EDAG raise the possibility of the detachment of the data from the manufacturing in the same way digital data allows one to manufacture your own copy of a record or DVD.
I expect that much of what EDAG has been working on will be deployed. How this new technology will interact with existing and future, unknown, processes is anyone´s guess. Based on my experience, new technology seldom drives out the old. Rather a new accommodation is reached in some form of synthesis. In the medium term I can see this techonology having benefits for medium-scale series production. Companies like Bently, Aston Martin and Lamborghini would well make use of the new methods and be able to charge corresponding prices. This could also revolutionise the concept of spare parts, a less glamourous aspect of motoring, but which promises to change the way manufacturers decide how long an older car remains viable for use. A car´s production life might only be one phase, followed by a long tail where even a modest demand for spares might allow even quite ordinary cars to carry on running with custom-ordered, custom-made components. While the existence of Dire Straits back catalogue does not threaten sales of future Dire Straits records, perhaps car makers might have to contend with their greatest hits still driving around with additively-manufactured spares prolonging their life.
EDAG deserve credit for this kind of long-range research which suggests new directions for car design plus ancillary benefits on energy consumption and resource use.
Further information and a full report on this can be found at EDAG.