From a technological viewpoint, many innovations were spotlighted at EMO Hannover 2017 in the field of Additive Manufacturing. Besides new machines for producing additive components, numerous exhibitors showcased new process variants, and demonstrated their capabilities as exemplified by innumerable additively manufactured components.
The proportion of additive manufacturing in the industrial environment continues to increase. This trend was discernible almost everywhere at the EMO Hannover, due not least to the numerous impressive additively manufactured application examples at various stands, with which the exhibitors showcased their hardware and software solutions. Additively manufactured products can not only be manufactured for optimum load-bearing capacity and weight by generatively building up bionic structures, but also permit the integration of additional functions, such as selective internal heat dissipation through integrated cooling channels. For metal printing, two processes currently predominate: the powder-bed process and laser deposition welding. Criteria for creating structures from the powder bed are primarily the high degree of design freedom, and fine resolution with 30 micrometres.
On its stand, EOS GmbH from Krailling exhibited an additively manufactured injection head for a rocket engine from the Ariane Group. By using powder-bed-based technology, the construction time could be reduced from three months to 36 hours, the costs halved, and the number of individual parts reduced from 248 to a single component. One issue gaining steadily in perceived importance is quality assurance in generative manufacturing, particularly when it comes to safety-relevant components for aircraft construction. In conjunction with MTU Aero Engines AG, EOS creates solutions that monitor the system’s general status by means of numerous sensors. Optimum layer quality is additionally assured by camera-based surveillance of the exposure process and the melting behaviour of the material.
Laser deposition welding
Besides the powder-bed process, the technology firm Trumpf from Ditzingen showcased at its stand the process of laser deposition welding, which enables build-up rates to be achieved that are ten times higher than the ones obtained in the powder-bed process. Here, the laser creates a melt pool on the component’s surface, into which metallic powder is inserted via a nozzle. This production process is used for applying wear-protection layers, repairing components, and for creating new structures. The Trumpf lasers could be viewed in operation on the multi-tasking machines of the Laser EX series, which the Japanese machine tool manufacturer Okuma was premiering in Europe on the stand opposite.
Consistently harmonised solutions from a single source, from the CAD/CAM software to combined machining of the finished part, were presented by the machine tool manufacturer DMG Mori, Bielefeld. With the new Lasertec SLM, components up to a maximum size of 300 mm x 300 mm x 300 mm can be created from the powder bed. The premiered Lasertec 65 3D even produces components with a diameter of 650 mm and a maximum height of 560 mm in an additive process. This machine, designed purely for additive manufacturing with the powder nozzle, requires, compared to the hybrid model, 45 per cent less footprint, and offers not only a 40 per cent larger work space but also technological innovations like different track widths, higher laser ratings of up to 4 kW, and manufacture featuring reactive materials like aluminium and titanium.
Additive 3D coating technology
Functional layers and component structures are created entirely without lasers using additive 3D coating technology from the machine tool manufacturer JG Weisser Söhne GmbH & Co KG in the Black Forest. Using a patented process, simple semi-finished material is rotationally imprinted onto a component’s surface, melted by the friction this generates, thus converting the semi-finished material into a component. The experimental machine showcased at the EMO Hannover offers for additive deposition a work space of about 800 mm x 300 mm x 150 mm. Basically, however, there would be a potential for utilising the technology on machines with different work spaces, and besides additive deposition, combining it with further machining units for mechanical reworking. According to this company, the advantages compared to the laser-based additive manufacturing process featuring a powder bed are that the semi-finished materials are 10 to 30 times more affordable, that the deposition rates of two litres per hour are 20 times higher for aluminium and even up to 100 times higher for steel. One significant disadvantage, however, is that currently, no complex structures can be created.
The metal-powder deposition process of Hermle Maschinenbau GmbH from Ottobrunn does not require any lasers either. In this thermal injection process, metal powder is accelerated to very high velocities with the aid of a carrier gas and applied layer by layer via a nozzle onto the component’s surface. The advantages of this process are that there are hardly any restrictions on the choice of material, provided that it is available in powdered form, and that it is possible to apply up to seven different materials in any desired mixing ratio on free-form surfaces. Other advantages are the low temperatures of 200°C to 300°C and the good amenability to a combination with subtractive mechanical machining processes, such as milling or turning, in a machining centre.
Software package for additive metal manufacturing
With the 3DXpert holistic software package, the American company 3D Systems from Rock Hill, South Carolina, offers a complete software package for additive metal manufacturing. This manufacturer, which itself also produces machines in the field of Additive Manufacturing, thus presented a solution constituting a producer-/process-independent variant for creating additive components. After the data have been imported and the component has been positioned, it is easy to subsequently create and optimise its structures and support geometries for the production operation. Then both the printing strategy for individual segments of the component is defined, and the scanning tracks are calculated. Since after additive manufacturing, it will be necessary to rework individual surface areas and remove support geometries, the software also offers a part-step for this step in the process as well.
Start-ups in the technological environment
To enable large components to be flexibly and cost-efficiently machined irrespective of the component’s dimensions, the start-up Picum MT, created by the Institute of Production Engineering and Machine Tools (IFW) at Leibniz University in Hanover, is adopting fresh approaches. Instead of bringing the component to the machine tool, the Picum One, an intelligent tool robot weighing about a mere 100 kg with its own single-software solution and innovative metrology, is brought to the component. According to the start-up, procurement and operating costs are thus avoided, as are inaccuracies increasing with the machine’s size. The Picum system docks with any desired component, and automatically determines its position in the space to an accuracy of 15 μm. The prototype is fitted with five-axis kinematics and a 7.5-kW milling spindle, and handles tasks like drilling, milling and grinding. In future stages of development, expansions to the system will be able to perform additional jobs like measuring, laser-cutting, and 3D printing.