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Innovative, tool-less manufacturing of complex and lightweight components

Maximum design freedom with industrial 3D printing enables the production of components with integrated functionality

 

Sustainable energy efficiency, the reduction of CO2 emissions, ongoing cost pressure and the continuing demand for innovation – automobile manufacturers are faced with major challenges. There is also a growing need for customer-specific solutions. However, the problem with small-series production and the increasing demand for customisation is that traditional tool-based manufacturing processes often cannot be applied profitably.

Innovative, tool-less EOS Additive Manufacturing provides a new approach to tackling the current challenges facing the automotive industry. It offers maximum design freedom while allowing the creation of complex yet light components with high levels of rigidity.

Additive Manufacturing enables the production of components with integrated functionality – without the need for tools, thereby cutting development and production costs. What is more, suppliers can respond to customer requirements by offering individualized serial production of parts.

Rapid prototyping based on Additive Manufacturing also means automobile manufacturers can increase the efficiency of their research and development processes, enabling them to get their products on the market more quickly. The focus here is not just on geometrical part accuracy: EOS is continuously expanding its range of new materials in order to ensure that parts are functionally reproducible, too, and can be installed directly in serial production vehicles.

EOS Additive Manufacturing technology – Automotive best-practice examples

Automotive: Formula Student Racing – Additive Manufactured lightweight battery housing for an electric-powered race car

Additive Manufacturing and its freedom of design helps students to racing success

It’s a sentence that the Global Formula Racing Team has taken to heart. They have built an electric vehicle for the Formula Student – the racing series for universities and higher education institutes that’s honing the skills of the next generation of engineers. Global Formula Racing is the first, and, until now, the only Formula Student team, formed from students from two different international universities – Oregon State University in the US, and the Baden-Württemberg Cooperative State University (DHBW-R) in Ravensburg, Germany. The international team utilises EOS technology in the manufacture and assembly of a safe and extremely compact container for the required battery pack of its racing car.

Challenge

The Formula Student began in the USA as an international construction competition for institutions of higher education. Students are given the opportunity to develop a racing car from a blueprint to the racetrack, and have the chance to compete against their peers from around the globe. The series now has two classes, one for combustion engines, and the second for vehicles powered by electricity. And, it’s no longer enough to just build a fast car. Entrants must adhere to cost and safety considerations, as well as factoring in numerous other requirements that need to be set out in a comprehensive and transparent plan.

On the racetrack itself what counts towards a podium finish includes acceleration, time on the circuit, and fuel efficiency – all placing high demands on the technologies in play. The Global Formula Racing Team has set itself the target of optimising performance by taking a closer look at the challenges faced in the previous season. As with all electrically powered motor vehicles, it was the battery – and more specifically, the storage capacity – that came under particular scrutiny.

Of course, the most critical consideration is safety. But, beyond that, there are a number of other important factors: The total weight of the construction – and therefore all of the component parts – should be kept to a minimum. Correspondingly, size must remain a consideration. “In 2011, more than anything it was the battery housing that gave us headaches,” explains Salvatore Decker of Global Formula Racing. “The system of the previous season still comprised a loose battery assembly that only fitted into the two casings with some effort. The housings were really big and heavy, and the heat dissipation wasn’t optimal. Also, the configuration of cables for each battery stack was particularly complex.”

Solution

The Additive Manufacturing (AM) process opened up new design possibilities for the construction of the complete energy storage system. The race team’s constructors were then able to plan from the outset for an optimised overall system solution. Because of the creative freedom offered by the housing, the complete battery pack could be compacted. The actual design process proved to be relatively simple, thanks to CAD software – and the usual steps could be followed right up to production.

 

“In these times of skilled labour shortages, young engineers are becoming more important than ever for maintaining Germany’s position as a center of industry. Because of this, we put our support behind the Formula Student: young technicians can experiment here and explore unchartered territories. Our technology fits perfectly with these aims,” explains Nikolai Zaepernick, Business Development Manager Automotive at EOS. “Laser sintering opens up new opportunities to manufacturers in the design and construction of their products. Incremental production processes allow engineers to create totally new designs and to construct them within a matter of hours.”

In this specific case, Salvatore Decker’s team used the EOS AM technology with a synthetic granule known as PA12. After the race team has transferred the prepared CAD data to the machine, the production began, layer by layer. For the creation of the CAD template, the engineers made use of their standard programme. The part was constructed from initial drafts to a finished component in just a few days. Because of the accuracy of the layered manufacturing process, the battery housing fit perfectly in place on the first try.

Results

In this way, the team was able to decrease the volume of the battery housing by half, and to reduce the weight by 40 per cent, in comparison to 2011. As a result, the dimensions of the housing were just 20 x 14 x 9 cm, which was enough to accommodate the 36 battery cells. The modular battery assembly in the 2012 car contained eight battery packs, a fact that made servicing the system far simpler.

Also, constructors were able to integrate the cable ducts and the cooling system directly into the housing during production. A complex reworking of the housing was thereby avoided, and the channeling for the cooling ducts could take place unrestricted. This, in turn, made the designing of the team’s cabling easier, and, as planned, the heat dissipation was improved. In line with safety considerations, the utilised material is fire-resistant, important due to the proximity to the energy storage. Owing to the thankfully infrequent, though nonetheless very real, possibility of a crash, and to the chance of a defective battery overheating, all materials and component parts must be resistant to fire.

“The high degree of design flexibility of the additive production process has really helped us a lot. It allowed us to match the design to our requirements and to reach an optimum compatibility with our proprietary system for battery management – and all of that within the shortest time frames, at a low cost, and critically, as an ultra-lightweight construction. This technology is absolutely perfect for our line of work,”

enthused a very satisfied Salvatore Decker.

Ferry Porsche would certainly have appreciated the passion of the young engineers and their electric racing car. And, you can be sure that in the coming season, thanks to the technologies at their fingertips, they’ll be at the track well in time for the green light.

Short profile

Global Formula Racing is the first innovative international cooperation of its type in the history of the US and European Formula Student competition. The ex-BA Racing Team of the Baden-Württemberg Cooperative State University (DHBW-R) in Ravensburg, Germany, and the Beaver Racing Team, from Oregon State University (OSU) in the USA, have pooled their resources to form a single team.

Automotive: Formula Student Germany – EOS supports racing team by producing a topology-optimized steering stub axle

Young engineers choose Additive Manufacturing (AM) to tap the full potential of the part

The greater the force in play, the greater the resulting counter-force – a relatively basic rule of physics. Such rules are particularly relevan

t in motorsports, where the stresses placed on the utilized materials are extreme. Taking the circuit at high speeds exposes both driver and car to the effects of such forces. The young constructors of the Rennteam Uni Stuttgart are constantly striving to optimize the construction pro

cess and the use of materials. More and more the sport demands that not only should the driver pilot the car ever quicker around the track but, within the principles of the Formula Student Germany series, he should do it safely. In the construction of the successful 2012 model the student engineers employed for the first time an additive manufacturing process in the building of the knuckles – and the car went on to win the title. EOS supported the team through its victorious Formula Student Germany season.

Challenge

The knuckle – also called the axle-pivot – connects the wheel axle with the wishbones and the track rod via a bearing. The braking system is then likewise fixed to it. The part conducts all the forces and momentum absorbed from the wheels to the wishbones and the tie rod, and on to the vehicle chassis itself. On the one hand, every constructor of an axle-pivot has the task of developing a part with the highest possible stability – otherwise the safety of the vehicle as a whole would be undermined. Besides a fracture, part deformation can also have serious consequences, as the kinematic design and, as a result, the drivability, would be negatively impacted. On the other hand, the wheel mounts cannot, for a number of reasons, weigh too much. Every additional gramme increases lap times, and the wheel mounts belong to the so-called unsprung mass of a vehicle. The less there is of this mass, the better the suspension and shock absorption will function. A low wheel-mount weight allows the car to sit better on the track – important for fast laps and safe racing. As a consequence, constructors are faced with the tricky task of finding the perfect balance between rigidity and weight. Previous production technologies offered the Stuttgart race team too little room to maneuver in the search for this perfect balance.

“The wheel mount we’d been using over the last few years had already achieved a good balance between weight and rigidity, but we were sure we could improve on it,” explains Yannick Löw from the Rennteam Uni Stuttgart.

“We produced the part using the classic precision casting process. This, of course, led to limitations in freedom of form, which meant that the part’s potential could never be fully realized. Even back then we’d decided that for the 2012 season we’d investigate new, innovative ways of manufacturing the steering stub axle.”

It didn’t take long for the team to decide upon the path to take: The EOS AM technology.

Solution

As early as the conceptual design phase, the engineers utilized the CAD software from Autodesk Within, whose programmers wrote their software specifically for the Additive Manufacturing (AM) process. The program makes possible the optimization of latticed micro-structures of variable densities following examples found in nature. Thanks to this tool the constructors were able to match the part perfectly to the structural requirements. In this way, they were able to give the knuckle precisely the required physical properties – light-weight plus rigidity.

“By the simplified, so called, 3D-Print process, our machine honed powdered metal granules with the help of a laser, layer by layer, into the required part,” explains Nikolai Zaepernick, Business Development Manager Automotive at EOS.

“The victorious team from Stuttgart decided on our partner Within’s software for the construction of the CAD model, as it was the most suited for the part and its purpose. The information for the manufacture of the part was provided for the Direct Metal Laser Sintering (DMLS) system from our universally deployable software, which had, so to say, translated the information from the existing 3D-CAD-model. The result was amazing and showed just how much the young engineers already understand about their subject.”

Once the team had designed the steering stub axle, the production of the first component parts followed immediately. The fact that the development and production time could be significantly shortened when compared to previously utilized processes was important for the team. There were a number of reasons for the time savings. One is that with additive manufacturing the need to build negatives or mould forms falls by the wayside. In addition the entire process, from design through fabrication is more precise, meaning that often no reworking or refining is required. In this case the constructors from Stuttgart reached a high production quality in a very short time with minimal honing for fit, so that the part was almost immediately race-ready.

Results

The advantages can be summed up in concrete figures: The weight of the part was reduced by 660 grammes, saving the Rennteam Uni Stuttgart 35 per cent. At the same time the engineers succeeded in increasing the rigidity by 20 per cent – big numbers for motorsports, and numbers that translate into faster lap times and reduced fuel consumption. The best testimony was delivered by the team with the result in the final race of the series – a victory at the Hockenheimring that crowned the Stuttgart race team as Formula Student Germany Champions 2012.

“We are thrilled to have been able to bring the Formula Student Germany 2012 title to Stuttgart. The freedom in the construction process offered by the DMLS technology from EOS has played an important role in our success,” says Löw. All those involved have shown with this victory that the engineering profession can be a lot of fun – and ultimately, that there are a multitude of interesting and exciting ways of responding to the shortage of technical specialists. And the allure of new technologies, such as additive manufacturing, can play a role in this, inspiring down the line more and more young people to take a serious look at a career in engineering.

Short profile

The Rennteam Uni Stuttgart is an independent club composed of highly motivated students from a broad range of fields. It takes part in the Formula Student racing series, a competition for young engineers, across Europe, as well as being involved in other international competitions.

Automotive: DHBW Engineering – Cooling System for Race Car Produced with the EOS P 396

Student Racing Series Impresses with Electric Motor Innovation

Enzo Ferrari, Ferry Porsche, Ferruccio Lamborghini – all of them built sports cars themselves because they could not find one that fulfilled

their desires. Every year, the dream of seeing your own race car at the start-line becomes reality for the participants in the Formula Student race series. In line with contemporary concerns, the focus is on the electric engine. The eSleek14, belonging to the DHBW Engineering Stuttgart team, has two electric motors, each with 60 horsepower. The electricity that feeds this speed machine is derived from batteries fixed laterally inside the vehicle. The construction of the air cooling system was supported by EOS in its role as Additive Manufacturing expert.

Challenge

The drive unit of a vehicle with an electric motor is a complex construction. The actual drivetrain is simpler than with conventional combustion engines. This must, however, be set against the complications of integrating the energy-storage units. In the eSleek14 these are comprised of lithium-polymer cells. The 24 modules have a total capacity of 6.7 kWh. This powerhouse is contained in a battery-housing made from fibre glass reinforced plastic in a sandwich-type construction. An integrated battery management system (BMS) controls the charge and discharge of the individual cells.

Because of the cell chemistry, the lithium-ion batteries used are flammable. The physical protection of the packs of cells is just as essential as the reliable ventilation of the system as a whole. This is because, alongside damage, overheating can also lead to a fire. In connection with the BMS, it is therefore vital to keep the build-up of heat under control. At the same time, optimized heat dissipation guarantees the best possible performance of the energy supply, and ensures the provision of power to the electric motor.

Another ever-present factor in the minds of the developers is the weight of each component. The battery unit must be as small and densely packed as possible in order to provide maximum power while taking up the least amount of space. Simultaneously, a defined range must be ensured – the proverbial squaring of the circle. This was the challenge with which the constructors of the eSleek14 were faced. Their response also needed to meet the crash requirements of the formula series.

Solution

The construction of the entire battery system was carried out in a way that ensured both mechanical and electrical protection, as well as providing optimized cooling. Three continuous channels guarantee the supply and venting of air to and from the electricity storage unit by way of the in-flowing and out-flowing airstream. The cooling air enters from the front, is distributed along the cells via the three channels, is then reunited by a manifold, and finally is drawn back and up to be expelled by way of a radial fan – a technical masterpiece on the part of the constructors.

Such components are, however, not available off the shelf. Additive Manufacturing processes offer a particularly valuable option in this area, as confirms David Köhler, the man responsible for both the construction of the batteries for the 2013/2014 car and the cooling concept for the high-voltage device: “We decided to have the cooling duct additively manufactured and, thanks to EOS’ technology, we had complete freedom of design. With such small quantities, injection-moulding didn’t make sense, and we would anyway, have had to make changes to the construction design.” For the 2013/2014 season, as in previous years, EOS trained the team in how best to exploit the advantages of Additive Manufacturing.

In the development of the battery container it was possible to realize not only the cooling channels between the individual modules, but also a cooling duct that directed the air at the end of the container, back outside in the most efficient way. In order to satisfy the strict internally set limits for the component weight, the team chose the lightweight fine polyamide PA 2200 for the construction. This material is characterized by its high rigidity and good thermo conductivity – perfect characteristics for application in motor racing.

Results

The air duct was produced using the EOS P 396, the laser beam melting the powdered material, layer by layer, to form the final component. Intensive component testing showed that the construction complied with all of the safety standards. The components successful application within the vehicle followed. The weight also met the desired criteria: the cooling duct component weighing just 77g. The importance of each gram is shown by the fact that the total weight of the eSleek14, at just 180kg, converts to a power/weight ratio of just 1.5 kg/hp. In comparison, each unit of horsepower in the Porsche 911 GT2 road version converts to 3kg in weight.

The team was able to increase the cooling performance by well over 100 %. In total, the temperature within the battery container fell from a high of 80 °C to just 50 °C. The distribution, in addition, is considerably more uniform. The results of the team at the Hockenheimring make it clear that nothing burns during the process of heat dissipation. Following a shock disqualification for excessive performance (!) in the acceleration test, the team showed its strengths in the endurance and efficiency competitions, with 4th place finishes in both categories. Despite the disqualification in the acceleration tests, the team was still able to achieve 7th place overall. Proof that the car is not only fast but also both reliable and efficient was provided by a race in Barcelona. “We kept pace with the best teams in the world: after Barcelona and Hockenheim we were in the top ten of the global rankings,” summarizes Köhler with pride.

It is worth keeping an eye on the long-term results which will become clear in the coming years. In its role as a training race series for the next generation of engineers the Formula Student has a value that is difficult to quantify.  “Today we are laying the foundations for the innovations of tomorrow.” This is something of which Nikolai Zaepernick, head of Strategy and Business Development at EOS is certain.  “For us this was a conscious choice: this type of application has great potential for use in electric road cars over the coming years.”

“EOS’ expert knowledge and technology have really helped us to get our electric powered race car eSleek14 on the track and recording great times. The advantages of Additive Manufacturing are very convincing: lightweight components, the fast realization of ideas, and all this possible for extremely small part quantities. The available materials mean that safety is never compromised. Thanks to the instruction received from EOS we were able to get the maximum out of the process – and prove ourselves out on the track.“

David Köhler, Assistant Head of Battery Development for the race team 2013/2014

Short Profile

The Baden-Württemberg Cooperative State University sponsors the DHBW Engineering Stuttgart e. V. club, which every year, enters a new racing team for participation in the Formula Student Electric. Each season, different project teams construct a race car within the specifications set by the series.

Further information

Rapid Prototyping with additive manufacturing solutions by EOS

Additive manufacturing is ideally suited for Rapid Prototyping. Thanks to the highest possible degree of design freedom, even complex shapes such as bionic structures can be manufactured. It is possible to manufacture physical presentation and functional prototypes quickly and cost-efficiently without the need for manual processing – directly using three-dimensional CAD construction data. This makes the entire product development process considerably faster.

Flexible construction and material variants

EOS systems build up prototypes as well as end products layer-by-layer. Different metal and plastic powder materials are available. Products made of different materials belonging to one material family (metal or plastic) can be processed on one machine. This is especially interesting for prototype manufacturing.

Companies in many sectors of industry are now making successful use of laser sintering processes in their development and manufacturing processes.

EOS Quality: Result of extensive experience and the highest manufacturing standards

EOS continuously monitors the quality of all components at every process step in the value-added chain and holds the relevant product certifications and validations

The aim of EOS quality policy is to identify current customer needs and future market demands early on and meet these by means of the appropriate organisational, technological and economic resources. This is the only way to ensure the success and competitiveness of the company in the long term.

The cornerstones of our quality policy are:

EOS has defined quality principles which we implement throughout the entire company:

  • Our quality benchmark is the satisfaction of our customers
  • We strive to achieve an outstanding level of quality in all products and services
  • Secure organisational and technological processes allow us to maintain our high quality standards both reliably and economically
  • Every employee endeavours to produce work of impeccable quality and avoid errors
  • Every employee contributes to achieving our company goals and improving quality through responsible, quality-conscious action
  • We promote awareness of quality in every employee by providing training programs and information events

The key factor in implementing our quality policy is management acting as a role model of our principles. For this reason, the managing directors and every manager in the company are committed to align their day-to-day actions with the defined quality policy.

Quality Management

EOS quality management is focused on development and continuous improvement using the best methods available, both in terms of organisation as well as processes, systems and product. This is done in partnership with all colleagues and departments. In this way we are able to meet customer demands, our company goals and legal requirements in an efficient manner.

EOS documents its high standards by means of important certifications of its quality management system.

  • EOS GmbH: certified according to ISO 9001 since 1998 for development, manufacturing, sales and service of systems and solutions for Additive Manufacturing using laser sintering technology
  • EOS Finland Oy: Certified according to ISO 9001 for design, manufacture and sales of metal materials and processes for EOSINT M systems. Also certified according to ISO 13485 and Directive 93/42/EEC for medical applications with Cobalt Chrome SP2 registered as class II medical product in EU for dental applications.
  • KVS GmbH: certified according to ISO 9001 for the development, production, testing and sales of polyamide powders and mixtures

EOS updates the QM processes according to standards in the medical and aerospace industries and according to GMP. EOS continuously monitors the quality of all components at every process step in the value-added chain. EOS also holds the relevant product certifications and validations (IQ, OQ, PQ) for all components of the Additive Manufacturing process. This includes processes and finished parts on the customer side as well as regulatory certificates and registrations in global markets.