The advantages of Additive Manufacturing (AM) highlight the capability to become an inherent part within the product development process. However, process specific challenges harm its further currency for industrial applications, for instance the high geometrical deviations. Different process factors influence the manufacturing accuracy and lead to large dimensional, form and positional deviations. Published research relative to deviations is difficult to compare, because it is based on several specimens that were manufactured with different processes, materials and machine settings. This fact emphasizes that reliable tolerance values for AM are hard to define in standards. Within this investigation, a universally applicable method was developed to examine geometrical deviations for AM processes. The main aim is the derivation of achievable tolerance values considering important influencing factors. Furthermore, due to the locally varying surface roughness of additively manufactured parts several tactile measurements were compared.

In diesem Beitrag werden zuerst die Hauptanforderungen für Schmierstoffe für die E-Mobilität dargestellt. Anschließend wird erklärt, welche technische Herausforderungen aus den sehr unterschiedlichen Anforderungen der einzelnen Komponenten resultieren. Danach wird der Einfluss der Grundölsorte, der Viskosität und der Additivierung diskutiert. Zum Schluss werden die typischen Unverträglichkeiten der eingesetzten Materialien und die damit verbundenen Schadensarten bzw. die Tests zur frühzeitigen Aufklärung, vorgestellt.

Laser Beam Melting (LBM) is an Additive Manufacturing (AM) process on the threshold of serial production. Therefore, LBM has to overcome different problems such as a low productivity and minor economic efficiency. Support structures are essential for LBM; however, these structures contribute to the mentioned topics, because their removal is time consuming and cost intensive. To enable design engineers and operators to increase the efficiency of LBM, design guidelinesfor support structures suitable for post-processing are developed. For this purpose, the effect of different design parameters on various evaluation criteria is considered. Suitability for post-processing can be evaluated in terms of cost, quality and time. Therefore, test specimens are built and parameter impacts on material consumption as well as the post-processing time is examined. Furthermore, the roughness of the parts is analyzed and used as an indicator for the removability of the support structure. In addition, warpage is measured and the impact of the parameters on this criterion is examined. Based on the results, suitable design guidelines and hints for support structures are developed in order to reduce time and costs during manufacturing and post-processing.

According to ISO / ASTM 52900, additive manufacturing (AM) is defined as "the process of joining materials to make parts from 3D model data, usually layer upon layer, as opposed to conventional manufacturing including subtractive manufacturing technologies and formative manufacturing methodologies” [1]. This results in significant advantages over conventional manufacturing methodologies, such as the production of topologically optimized, complex structures, lower material consumption or shorter product development cycles. In order to be able to use these advantages, the possibilities and restrictions of the processes must be known. In particular, selective laser beam melting (SLM), in which a powdery metallic starting material is melted by means of a laser, requires a sound understanding of the process. For this purpose, design guidelines have been presented in various scientific papers. These design guidelines help to design a component in such a way that it can be manufactured successfully using additive manufacturing. These so-called “AMsuitable design guidelines” can be found among others at Adam, Kranz and Thomas [2,3,4,5]. In contrast to established manufacturing processes, the post-processing of additive components is divided into two steps. First, the AM immanent post processing, such as the removing of the component from the building platform or the removing of the remaining powder. These post-processing steps are in the following referred to “post-processing”. Secondly, the subsequent post-processing steps to improve the component properties, such as milling and turning or a stress-relief annealing. These are referred to as “finishing” and form the focus of this paper. With regard to a successful finishing of additively manufactured components, design guidelines must be taken into account that consider the finishing inherent restrictions and possibilities. In the following, these design guidelines are referred to “finishing suitable”. They can deviate significantly from those of conventionally manufactured components in the case of additively manufactured components. Although there are some investigations that deal with the post-processing of additively manufactured components [6,7], there are hardly any design guidelines that are suitable for finishing [8]. Therefore, knowledge about the finishing of additively manufactured components is based on experimental experience rather than on scientific knowledge. For this reason, design guidelines for a finishing suitable design must be methodically determined and quantified. These quantified design guidelines can be used for an automated design check on complex components like topology optimized geometries.

Additive Manufacturing (AM) processes generate plastic or metal parts layer-by-layer without using formative tools. The resulting advantages highlight the capability of AM to become an inherent part within the product development. However, process specific challenges such as a high surface roughness, the stair-stepping effect or geometrical deviations inhibit the industrial establishment. Thus, additively manufactured parts often need to be post-processed using established manufacturing processes. Many process parameters and geometrical factors influence the manufacturing accuracy in AM which can lead to large deviations and high scatterings. Published results concerning these deviations are also difficult to compare, because they are based on several geometries that are manufactured using different processes, materials and machine settings. It is emphasized that reliable tolerances for AM are difficult to define in standards. Within this investigation, a uniform method was developed regarding relevant test specimens to examine geometrical deviations for Laser Beam Melting (LBM), Fused Deposition Modeling (FDM) and Selective Laser Sintering (SLS) in order to derive geometrical tolerance values. The manufactured test specimens were measured using tactile and optical systems to examine the occurring geometrical deviations. The results show possible geometrical tolerance values that were classified according to the international standard DIN EN ISO 286-1.

The design of additively manufactured components requires a rethinking in the design process. This is inhibited by a lack of knowledge about additive manufacturing technologies. For this reason, a large number of design guidelines have been developed in recent years. In their present form the design guidelines are not suitable for processing in a software algorithm, since the guidelines have a certain redundancy and partly influence each other. This paper describes several steps to consolidate the existing guidelines and to prepare them in a way that they can be used in a software algorithm for a design check. Therefore, existing guidelines are collected, prioritized and quantified with regard to their relevance for a robust production. To quantify the guidelines, test specimens are developed, produced and evaluated in order to obtain a limit value for the geometric properties. With these limit values, quantifiable design guidelines can be applied to designers and software tools.

In der Industrie entsteht aufgrund des dynamischen Wettbewerbsumfelds ein zunehmender Drang nach verkürzten Produktentstehungszeiten, hoher Funktionsintegration und individualisierten Produkten. Mithin erlangen additive Fertigungsverfahren eine zunehmende industrielle Bedeutung. Das Laser-Strahlschmelzen (LBM) als additives Verfahren ist hierbei beispielhaft hervorzuheben, da es bereits im Bereich des Prototypenbaus und der Kleinserienfertigung ein etabliertes Verfahren ist, das an der Schwelle zum Einsatz in der Serienproduktion steht. Entscheidendes Hemmnis für den Einsatz der additiven Fertigungsverfahren bildet die fehlende methodische Ausnutzung der gestalterischen Freiheiten und Randbedingungen durch die vergleichsweise neuartige Gruppe an Fertigungsverfahren im gesamten Produktentstehungsprozess. In der Produktentwicklung bildet die Konstruktionsmethodik einen möglichen Ansatz, um gestalterische Freiheiten und Vorteile additiver Fertigungsverfahren bereits in frühen Phasen der Entwicklung gezielt zu berücksichtigen. Hierfür werden aufgrund bestehender und allgemein anerkannter Konstruktionsmethoden (z.B. VDI2221, Pahl/Beitz, etc.) Anknüpfungspunkte aufgezeigt, die eine Implementierung, speziell des Laser-Strahlschmelzens, ermöglichen. Besonderes Augenmerk wird in dieser Veröffentlichung auf die beiden Konstruktionsphasen Konzeption und Gestaltung gelegt. Hierzu werden Ergänzungen oder Anpassungen der bestehenden Konstruktionsmethoden vorgestellt. In besonderer Weise wird dabei auf die Einbringung und die Vorteile der additiven Fertigungsverfahren eingegangen.

Neue Konstruktionsabläufe und Potentiale bei der Gestaltung additiv hergestellter Bauteile verlangen insbesondere im Konstruktionsprozess ein Umdenken. Fehlende Kenntnisse über die additive Fertigungstechnologie hemmen zusätzlich dieses Umdenken [HHD06, WC15]. Um die verhältnismäßig neue Fertigungstechnologie zugänglicher zu machen, wurden in den letzten Jahren verschiedene Konstruktionsempfehlungen erarbeitet. Die Vielzahl an Empfehlungen erschwert dem Konstrukteur allerdings einen entsprechenden Überblick zu behalten und für ihn relevante von nicht relevanten Empfehlungen zu sondieren. Aus diesem Grund wurden öffentlich zugängliche Empfehlungen für das Laser-Strahlschmelzen zusammengetragen und einer Priorisierung unterzogen. Das Ergebnis beinhaltet Konstruktionsempfehlungen, die einen relevanten Einfluss auf die Bauteilfertigung, die Bauteilqualität und -funktion haben. Durch Abstraktion dieser Empfehlungen konnten Richtlinien erarbeitet werden, die für eine softwareseitige Gestaltprüfung verwendet werden können. Durch diese Gestaltprüfung können Bauteile beliebiger Komplexität, zum Beispiel feine Gitter oder topologieoptimierte Strukturen, bereits vor der Fertigung hinsichtlich der Einhaltung relevanter Konstruktionsrichtlinien überprüft werden. Der Gestaltprüfer greift dabei auf eine Datenbank zurück, die zulässige, quantitative Grenzwerte von Konstruktionsrichtlinien enthält. Diese Grenzwerte werden im Folgenden Attributsausprägungen genannt und können experimentell ermittelt werden. Hierfür wurden standardisierte Prüfkörperbaujobs entwickelt, die alle notwendigen Prüfkörper zur Ermittlung der Attributsausprägungen enthalten und deren Auswertung eine Erweiterung der Datenbank hinsichtlich

This paper reports on the experimental development and the theoretical analysis of the scanning laser epitaxy (SLE) process that is currently being investigated and developed at the Georgia Institute of Technology. SLE is a laser-based manufacturing process for deposition of equiaxed, directionally solidified and single-crystal nickel superalloys onto superalloy substrates through the selective melting and re-solidification of superalloy powders. The thermal modeling of the system, done in a commercial CFD software package, simulates a heat source moving over a powder bed and considers the approximate change in the property values for consolidating CMSX-4 nickel superalloy powder. The theoretical melt depth is obtained from the melting temperature criteria and the resulting plots are presented alongside matching experimental micrographs obtained through cross-sectional metallography. The influence of the processing parameters on the microstructural evolution, as evidenced through observations made from the micrographs, is discussed. This work is sponsored by the Office of Naval Research, through grants N00173-07-1-G031 and N00014-10-1-0526.

Additive Fertigungsverfahren (engl.: Additive Manufacturing, kurz: AM) ermöglichen die werkzeuglose Herstellung von Komponenten und kompletten Baugruppen direkt aus dem 3D-CAD-Modell. Insbesondere additiv hergestellte Leichtbaukonstruktionen weisen ein hohes Potential für den Elektromaschinenbau auf. In diesem Paper werden erste Ansätze zur additiven Fertigung einer Rotorwelle für eine permanentmagneterregte Synchronmaschine (PMSM) aufgezeigt. Die Verbesserung einer ausgeprägten Leichtbaukonstruktion der Rotorwelle sowie die Charakterisierung des additiv verarbeiteten Werkstoffs werden aufgeführt. Hierzu wurden Prüfkörper aus dem Werkstoffs H13 (1.2344) hergestellt. Des Weiteren wurden Prüfkörper additiv gefertigter Gitterstrukturen entwickelt und untersucht. Zur Werkstoffcharakterisierung wurden sowohl mechanische Eigenschaften ermittelt, wie die Streckgrenze, die Zugfestigkeit und die Härte als auch elektromagnetische Eigenschaften, wie die Koerzitivfeldstärke, die elektrische Leitfähigkeit und die Permeabilität. Die Ergebnisse zeigen, dass die magnetischen Eigenschaften von H13 durch eine angeschlossene Wärmebehandlung deutlich verbessert werden konnten. Im Anschluss an die Werkstoffcharakterisierung wurde ein innovatives Leichtbau-Rotorwellenkonzept mit internen Gitterstrukturen entwickelt. Verglichen mit einem konventionell gefertigten Rotor konnte die Rotormasse um 25% reduziert werden sowie das Massenträgheitsmoment um 23% reduziert werden bei einer Testdrehzahl von 3000 U/min und einem Drehmoment von 71,98 Nm.

Fused Deposition Modeling (FDM) is used for prototypes, single-partproduction and small batch productions of thermoplastic components. This manufacturing technique has the huge benefit that no forming tool is needed. The knowledge about dimensional deviations which occur in the FDM process is necessary for calculating fits and for determining tolerances. A major challenge is the reproducibility of the dimensional accuracy of FDM parts and the reproducibility between different FDM machines. There are many influential factors on the dimensional accuracy in the FDM process for example geometric, material-specific or process-specific factors, which are considered in this paper. The influence of the part position on the build platform of a Stratasys Fortus 400mc is analyzed in terms of the achievable dimensional accuracy. For this purpose, the temperature distribution in the actively heated build chamber is investigated and possible correlations to the dimensional accuracy are identified. The reproducibility of one machine is examined by a multiple production of the test specimens. In addition, a comparison with three other FDM machines from Stratasys is made. Afterwards, the long-term reproducibility of the dimensional accuracy is verified to consider how environmental influences such as maintenance or modification of machine components affect the dimensional accuracy of the FDM process.

Additive Manufacturing (AM), also known as 3D printing, is a relatively new technology which enables the toolless production of components and entire assemblies directly from a CAD file. Today, the technology is still not widely used in industrial production. It is mainly limited to special applications, although it shows great potential. In this paper, first approaches are shown to apply AM to the production of rotors for permanent magnet synchronous machines (PMSM). The possibilities of a lightweight design with a low moment of inertia as well as the influence on the magnetic anisotropy for an improved sensorless control of PMSM are pointed out. The results clearly demonstrate the great potential of additive manufacturing in electrical engineering applications.

In the polymer laser sinter process, part quality depends on many influencing factors along the process chain. For application of the technology in series production and an integration of laser sintered parts into a technical environment, the dimensional accuracy of parts has to be taken into account. Therefore, occuring deviatons and their scattering have to be reduced and homogenized based on process parameters and build job layout. In this work, the dimensional accuracy of laser sintered parts is analyzed for varied parameter values. Influences of different process and geometrical build job parameters on dimensional deviatons are figured out. The experimental results allow an evaluation of more and less important influences. Finally, measures are deduced to reduce and homogenize dimensional deviations.

Additive manufacturing creates parts in layers without using formative tools. Compared to established manufacturing processes, additive manufacturing offers many advantages. However, only a few research institutions and technology-leading companies use additive manufacturing for end-use part production because relevant challenges have not been sufficiently researched yet. Missing restrictions become apparent in the available geometrical accuracy. The objective of this investigation was the experimental determination of dimensional tolerances using standard parameters. To this end, a methodical procedure was set up. Based on experimentally determined deviations, dimensional tolerances were derived.