New Products, One Layer at a Time

Bones, engines and shoe soles from the printer: How additive manufacturing is revolutionizing our production world

Additive Manufacturing

With Additive Manufacturing, the world of fantasy seems to be conquering the world of production. How much of this is reality, in industrial applications and at the Fraunhofer laboratories? Today, what the end-user knows as "3D printing" is still rare in homes, but it has already reached industrial product development and is generating end-products in fields ranging from mechanical engineering to aviation and medical technologies.

A tempting prospect: Instead of anxiously waiting a long time because the lamp bracket on your bicycle has broken in a fall, you simply download the data from the manufacturer and send it to the 3D printer in your home office to make a new bracket. A short time later you install the home-made replacement part and your bike is safe for traffic once again. Often the media like to report on such scenarios, but they only apply to a small number of end-users. In the industrial sector, on the other hand, 3D printing procedures are slowly but surely gaining a secure foothold.

Market Volume of Approximately Five Billion Euros

"A conservative estimate of the worldwide market volume fo additive manufacturing machines, products and services in 2015 is almost three billion Euros, and in 2019 at approximately five billion euros," predicts Dr. Bernhard Müller, spokesman of the Fraunhofer Additive Manufacturing Alliance and group manager for additive manufacturing at the Fraunhofer Institute for Machine Tools and Forming Technology IWU. In 2008, the Fraunhofer Additive Manufacturing Alliance began consolidating the activities of the Fraunhofer Institutes. "Because of the high media prominence, we're receiving more and more customer inquiries. Many are worried that they'll miss out on an important development if they don't keep up on things," Müller reports.

The German federal government's Expert Commission on Research and Innovation (EFI) also predicts an increasing significance for 3D printing. The Commission dedicated a separate chapter to the innovative production method in its 2015 annual report.

"Fraunhofer: An Excellent Partner"

One of the industrial partners jointly won over by the Alliance is John Deere. The agricultural machine manufacturer sees major future potential for additive manufacturing in particular for tools, components with functional integration and replacement parts. "Fraunhofer works neutrally between the academic and industrial sectors and is thus an excellent partner for us in the context of this development," says Steffen Fischer, Manager Manufacturing Innovation at John Deere. The company is counting on support in the design field, but also in connection with case studies and the evaluation of materials.

3D Revolution

The New Flexibility of Production

The Cuttlefish is the Key
© Photo Fraunhofer IGD

The Cuttlefish is the Key

Researchers at the Fraunhofer IGD have developed the software product "Cuttlefish" to improve the printed results of the 3D printer.

Propelled Like the Octopus
© Photo Fraunhofer IPA

Propelled Like the Octopus

When constructing a silent drive system for boats and water sports equipment, researchers looked to the octopus for inspiration. The drive system is a product of the printer.

Complex Ceramics
© Photo Fraunhofer IKTS

Complex Ceramics

Additive manufacturing techniques enable component geometries that were never possible in the past, while conserving resources at the same time.

Outer sole of a running shoe sintered from TPU

Laufschuh aus Polyurethan
© Photo Fraunhofer UMSICHT

Die Außensohle des Laufschuhs ist aus thermoplastischem Polyurethan (TPU) gesintert und extrem abriebfest.

One current example of the Alliance's activities is the plastic shoe sole. "We can provide professional soccer players with customer-tailored shoes featuring soles designed to fit precisely the form of their feet," explains Dr. Jan Blömer, group manager for additive manufacturing at Fraunhofer UMSICHT. Blömer develops fine-grain plastic powder for selective laser sintering, an additive manufacturing technology which is in the meantime in widespread use. "This lets us produce flexible, highly-robust components in a matter of hours."

The production of the shoe sole works something like this: First the computer slices the sole into virtual layers 1/10 of a millimeter thick. In the printing system a blade spreads an equally thin layer of powder on a platform, the powder bed. The computer data then guides a laser which selectively heats the powder to over its melting point, wherever the component is supposed to take shape within the layer. At the points which are not heated, the powder remains loose and functions as support material. The platform then moves down a distance equivalent to one layer, the next layer of powder is applied, once again selectively sintered, and so on. In this case the collaboration partner was Bayer AG, manufacturer of the thermoplastic polyurethane (TPU) used for the shoe sole. "We received an inquiry as to whether or not TPU could be laser sintered," Blömer recalls. "Bayer provides the material to a number of different shoe manufacturers who are interested in creating their prototypes using 3D printing in the future."

Additive Manufacturing in Medicine

The combination of 3D scanner, CAD technology and additive manufacturing techniques forms a new digital workflow inspired by nature for new, future-oriented products.

The medical branch in particular places high demands on individual solutions, for example for prostheses. The Fraunhofer IPA in Stuttgart improved on an additive procedure, making it possible to produce custom-fitting prostheses at low cost. The dimensions of the patient's body are entered in a CAD program used in Fused Layer Modeling (FLM) production, and then the printing material, a cost-effective plastic, is melted locally with a movable heat jet and applied layer by layer. In addition to medical applications, among other things the team led by Steve Rommel also improved on the Fused Layer Modeling process to make it viable for technical plastics under industrial conditions. The Fibre PrinteR print head has been developed in recent years, making it possible to create structural elements as well as to add a continuous fibre to the plastic filament.

In the future Fraunhofer scientists even plan to print artificial tissue: Since 2011 a consortium of 16 European partners from industry and research have been working on constructing a multi-layer tissue structure with a supply system of vessels. The Fraunhofer ILT plays the leading role, with other participants including Fraunhofer IAP, IGB, IPA and IWM. "Up to now skin models that work without this type of vascularization can only be cultivated in surface areas of less than one square centimeter and with thicknesses of less than two millimeters," explains Dr. Arnold Gillner, head of the competence area Ablation and Joining at the ILT. Additive manufacturing technologies, optimized vascular geometry calculated via simulation, adapted biofunctional materials and the cultivation of relevant cell types are combined in a process enabling construction of vascularized fatty tissue and ultimately of artificial skin.

Gefäßstruktur für ein Hautmodell
© Photo Fraunhofer ILT

Vascular structure for providing blood to a skin model.

Several institutes are working on additive manufacture of bone implants, including the Dresden section of Fraunhofer IWU. One of the great challenges in surgery is the restoration of the eye socket: If the bony, intricate eye-socket is shattered in an accident, it has to be painstakingly reconstructed. "As a rule surgeons cut a perforated sheet manually and insert it during the operation," explains Christian Rotsch, head of the Medical Technology department. Together with industry partner Alphaform Claho, the IWU is introducing a new procedure: First the deformed half of the face is virtually modeled in 3D.

On the basis of this data, Alphaform Claho produces eye socket implants within two to three days. Currently the company is delivering five to ten such implants every month. The MUGETO hip implant was also developed at the IWU. The implant's integrated "cavities" can be used to deposit medicine for example, which is then administered via the implant-bone interface. This improves the patient's healing process and can spare the patient replacement operations at the same time, an important step towards lifelong implants. MUGETO implants are manufactured using laser melting, a process extremely well suited to sector-independent industrial implementation according to studies by Roland Berger and automotive development engineers EDAG. "Fraunhofer is clearly in the lead here," says Alliance spokesman Müller.

Hüftimplantat MUGETO
© Photo Franhofer IWU

Today medical implants can be manufactured from bio-compatible materials such as titanium, cobalt-chromium or stainless steel. One example is the MUGETO hip implant with integrated cavities for medicinal deposits.

Selective Laser Melting and Laser Metal Deposition

Selective laser melting of metal powder is similar to the laser sintering process described above, however, metal is being processed instead of plastic and is actually melted rather than just sintered. As with the sintering process, the powder is built up layer by layer until the finished workpiece can be removed from the powder. Here the leftover powder can be recycled. This procedure makes it possible to manufacture complex workpieces which can be designed much more easily than with standard metal components.

This makes the technology particularly attractive to the aviation sector. "Every kilogram of weight we save is money in the bank. And the comparatively small batch sizes are accommodating additive manufacturing scenarios," Müller points out. "This is why the aerospace industry is currently the principle driver in establishing metal additive manufacturing processes."

For example, for Rolls-Royce Deutschland the ILT repairs components from various aircraft engines, for example chassis parts and a variety of labyrinth seals. "We've been certified accordingly," says Dr. Andres Gasser, Laser Material Deposition group manager at the ILT. "We've developed an automated process for turbine vanes which is to be implemented this year in very small series production." In laser material deposition the metal powder is applied directly to the workpiece using a nozzle holding the laser.

In contrast to selective laser melting there is no powder bed here. This makes it possible to process different powders within a single level or from one layer to the next, so that material combinations and gradients can be produced. To enable future use with wide-area coatings for protection against corrosion and the effects of wear, ILT recently developed "High-speed laser metal deposition". "This has increased our speed by a factor of 200 and makes it possible to partially replace galvanic procedures and thermal spraying," Gasser adds.

Rapid Prototyping

Additive manufacturing was preceded by rapid prototyping, a process which has in the meantime been expanded towards series production. But this doesn't mean prototyping has disappeared from the scene entirely, just the opposite. "In the automotive industry, the increasingly high product development frequency – in the meantime a new model comes out every four years – calls for constant and quickly operable prototypes," Müller explains. "This has made additive manufacturing a permanent fixture in product development." Thus for example the ILT was able to collaborate with the BMW Group to manufacture the functional prototype of a body part in a very short time using laser melting.

Not Just Less Expensive Manufacturing: New Solutions Are Possible Too 

"The question is not: Can I produce my product cheaper with 3D printing?" Müller says. "Much more it's: What completely new products and procedures might fit with my portfolio? Additive manufacturing makes solutions possible that we previously thought would be impossible to realize." The Fraunhofer Institutes have an excellent starting position for becoming the driving force behind a technology enabling a wide variety of new products and processes.