Aufsätze und Manuskripte

Zuverlässige, wiederholbare Bauteileigenschaften sind unabdingbar um das Herstellungsverfahren Polymer Lasersintern im industriellen Prozess-Portfolio vieler Firmen aufnehmen zu können. Einige Unternehmen und Institute haben sich daher in jüngster Zeit mit dem Thema der reproduzierbaren Bauteileigenschaften beschäftigt. Mit der hier vorgestellten und angewandten Methodik wird nicht nur der Prozessablauf vom Bauteil bis zu Nachbearbeitung betrachtet, sondern auch die Maschinenperformance in einem Ringversuch und über einen längeren Zeitraum geprüft. Rückgrat dieser Untersuchung bildet hierbei der aus der Six Sigma Lehre stammende DMAIC (Define - Measure - Analyse - Improve - Control) Verbesserungszyklus. Hierfür wird ein Standard-Prozess definiert. Diesem folgend werden die für die Industrie oder den Anwender interessanten Messungen aufgenommen und analysiert. Anschließend wird der Prozess sowie die Messmethodik optimiert und auch Kontrollmethoden definiert. Für die Anwendung der entwickelten Methodik wird exemplarisch der Maschinentyp EOS P396 mit PA2200 untersucht. Daten für die Bestimmung der Mechanik, der Optik und der Haptik sowie für die Dimensionen und die Bauteildichte werden als Qualitätskriterium aufgenommen und über einen längeren Zeitraum analysiert. Weiteres Ziel ist es, den Messaufwand zu reduzieren und die Qualitätssicherung im Serienbtrieb zu gewährleisten.

Structural parts for aviation have very high demands on the development and production process. Therefore, the entire process must be considered in order to produce high-quality AM metal parts. In this case study, a conventional part was selected to be optimized for AM. The process presented includes component selection, design improvement with a novel approach for topology optimization based on the AMendate algorithm as basis of MSC Apex Generative Design,component production on a SLM 250 HL and post-processing including heat treatment and surface smoothing. With the topology optimization a weight reduction of ~60 % could be realized, whereby the stress distribution is more homogeneous. Furthermore, the challenges of support optimization and post-processing have to be addressed, in order to produce competitive parts.

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.

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.

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.

Requirement changes are a major cause for project failure. A systematic approach to manage those changes from the very beginning should be an in-tegral part of each development project. Although this is accepted in both sci-ence and industry, there is no adequate approach to tackle the issue, especially in the context of interdisciplinary systems. In this paper, a secondary analysis is done to identify all information that is necessary to manage those changes efficiently. The demanded information is pictured in a reference model and then mapped with the capabilities of existing approaches. Based on this, research gaps are identified and used to guide future research efforts.

In diesem Beitrag wird ein Ansatz vorgestellt, welcher die Bewertung des Risikos von Anforderungsänderungen in der Entwicklung mechatronischer Systeme ermöglicht. Ausgehend von einer Anforderungsliste werden die Wechselwirkungen in einer Requirements Structure Matrix (RSM) teilautomatisch erfasst. Parallel werden Anforderungen in Bezug auf ihren Ursprung („Einflussbereich“) kategorisiert und darauf aufbauend priorisiert. Diese Priorisierung basiert auf dem Veränderungsrisiko und wird durch die drei Kriterien „Dynamik“, „Unsicherheit der Wissensbasis“ und „Relevanz für den Entwicklungsprozess“ charakterisiert. Das Vorgehen wird anhand strukturierter Interviews mit Projektleitern und Entwicklern und der Fallstudie eines Pedelecs als mechatronischem System validiert. Durch die Anwendung der Methode können disziplinübergreifende Abhängigkeiten von Anforderungen zur Reduktion von Iterationen in der Entwicklung mechatronischer Systeme – wie dem Pedelec – berücksichtigt werden.

In diesem Beitrag wird ein Ansatz vorgestellt, welcher die Bewertung des Risikos von Anforderungsänderungen in der Entwicklung mechatronischer Systeme ermöglicht. Ausgehend von einer Anforderungsliste werden die Wechselwirkungen in einer Requirements Structure Matrix (RSM) teilautomatisch erfasst. Parallel werden Anforderungen in Bezug auf ihren Ursprung („Einflussbereich“) kategorisiert und darauf aufbauend priorisiert. Diese Priorisierung basiert auf dem Veränderungsrisiko und wird durch die drei Kriterien „Dynamik“, „Unsicherheit der Wissensbasis“ und „Relevanz für den Entwicklungsprozess“ charakterisiert. Das Vorgehen wird anhand strukturierter Interviews mit Projektleitern und Entwicklern und der Fallstudie eines Pedelecs als mechatronischem System validiert. Durch die Anwendung der Methode können disziplinübergreifende Abhängigkeiten von Anforderungen zur Reduktion von Iterationen in der Entwicklung mechatronischer Systeme – wie dem Pedelec – berücksichtigt werden.

Due to the great popularity of the Fused Deposition Modeling (FDM) process, the material market is growing. In particular, processing of high-temperature materials such as PEEK is demanding. The aim of the investigations is to test different PEEK materials regarding their processability in the FDM process. An unreinforced PEEK, a thermally conductive PEEK as well as a carbon fiber reinforced PEEK are investigated. The processability is assessed with the help of the weld seam strength. The assessment of the weld seam strength is carried out by building tests. For this purpose, a special method developed at the DMRC is used. In addition, a welding width factor between the strands deposited on each other is calculated and compared. Finally, a welding factor is determined to enable the comparison between the different materials. With this procedure, the influence of varying nozzle and build chamber temperatures on the achievable weld seam strengths is evaluated.

The Arburg Plastic Freeforming (APF) is an additive manufacturing process that allows three-dimensional, thermoplastic components to be produced in layer by layer. The components are generated by depositing fine, molten plastic droplets. One of the main advantages of the APF process is the open machine control. Thus, the process parameters can be adapted and optimized for the individual applications. The optimization is carried out on the basis of a variation of the process parameters using a statistical design of experiments. Relevant process parameters are the layer thickness, the form factor, the raster and delta angle as well as the overlap between the contour and the filling of a layer. In addition, the nozzle and build chamber temperatures are varied. Using this procedure, the effects of the influencing parameters on the mechanical properties and the interactions between the influencing parameters are analyzed and converted into mathematical models. On the basis of the results and the models, guidelines will be developed to assist the user of APF technology in the systematic process configuration for their own applications. The material used is ABS, one of the most frequently used amorphous thermoplastics in additive manufacturing. The mechanical properties are determined on the basis of tensile tests and the characteristic values tensile strength, elongation at break and Young's modulus. The results should show the performance of the APF technology in regard to the mechanical properties.

The mechanical properties of thin-walled plastic components are limited. One approach to improve the strength or stiffness of these components is to reinforce the thin-walled areas with an individually adapted Fused Deposition Modeling structure. Fused Deposition Modeling (FDM) is one of the most commonly used additive manufacturing processes. This process is characterized by the deposition of a fused, thermoplastic filament. Depending on the form of the reinforcement structure, the resulting hybrid structure should show higher strength or stiffness. The objective of the project is to determine constructive design and process guidelines for FDM structures. The FDM structure is to be used as a partial reinforcement for lightweight components and be adapted to the respective load conditions. Because of the lightweight application, the FDM structure should also have the lowest possible weight. The optimization of the FDM parts for different load cases is realized by adapting the design parameters. These parameters influence the layer generation and therefore also the inner structure of the FDM parts. In preliminary studies, the manufacturing restrictions of the FDM process are defined. The specimens are manufactured based on the Design of Experiments. To determine the static strength properties, different tests (tensile, compression, flexural, torsion and impact) are carried out. The investigations show that the filling strategy affects the mechanical properties. As a result of the investigations, design and process guidelines for the FDM structures are established according to the load conditions.

Additive manufacturing processes, like the Fused Deposition Modeling (FDM) process, do not need product-specific tools and create parts directly from the CAD data. In the FDM process, the semi-finished product, a wire of a thermoplastic polymer, is melted and forced through a nozzle. The continuous positioning of this nozzle allows the polymer to weld together strand by strand and layer by layer to produce a component. Because no mold is used in the FDM process, no holding pressure can be generated as in injection molding processes, in which the holding pressure is used to minimize the shrinkage and warpage of the part. In the FDM process, the part is generated in an ambient pressure environment. Each strand cools down and shrinks separately. This causes residual stresses in the part that can lead to major warpage and a complete stoppage of the process. This is the main reason why the material selection in the FDM process is restricted in comparison to conventional polymer processing technologies. In this paper, the warpage of different polymers is quantified as a criterion for evaluating the processability of polymers in the FDM process. Due to the process principle, the part properties in the FDM process are mainly influenced by the machine quality and the data processing, so that it is difficult to test a material for FDM independently of the machine and the data processing. Considering these influences, a custom-built specimen is created to test and quantify the warpage of different types of blended and reinforced polyamide 6. Considering the experimentally investigated warpage, the materials can be evaluated and the warpage can be related to the shrinkage investigated in pvT measurements. This procedure allows the machine- and process-independent rating of the processability in terms of warpage for different materials. Alongside other criteria, this is a necessary step to develop new materials with good processability in the FDM process.

although it shows great potential. In this paper, first approaches

results clearly demonstrate the great potential of additive

Function integration is a key issue for an efficient and economic usage of Additive Manufacturing. An efficient heat transfer by topology optimized structures is a rarely considered approach which will be outlined with an exemplary electronic housing which has been newly designed. A commercial projector unit, whose electrical components in total produce 38 W, shall be integrated in the closed housing and passively cooled by natural convection. Topology optimized structures shall be generated in the inner part of the housing to transfer the heat homogenously from the projector components to the housing wall while simultaneously minimizing the mass. At the outside of the housing walls, lattice and rib structures are applied to increase the effective surface for heat transfer by natural convection and radiation. Furthermore, the housing geometry is optimized regarding a minimization of support structures to reduce the post-processing effort. Finally, the housing shall be built of AlSi10Mg by SLM.

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.

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.

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

Theimplementation of additive manufacturing as an industrial manufacturing process poses extraordinary challenges to companies due to their far-reaching differences to conventional processes. In addition to the major differences in the production process, the pre and post process steps in particular also require a rethinking for companies and their employees. To overcome these challenges and specifically to assist SMEs in the integration of technologies five industrial companies are researching together within research project "OptiAMix", funded by the German Federal Ministry of Education and Research (BMBF) and coordinated by the Paderborn University. This paper focuses on the development of an optimal and standardized process chain and its implementation in a general integration methodology. This enables the standardized integration of additivemanufacturing in order to create a uniform understanding of the procedures and tasks within the company for the industrial application of additive manufacturing at an early stage as well as the full exploitation of its high potentials. Therefore, the methodology also includes other technology-specific components such as strategic component selection, decision support for "make or buy" and the implementation of automated component marking.

Changing requirements have a broad impact on product development processes. In this paper, a novel approach towards structuring requirements is proposed. Based on a requirements list, interrelations of requirements are assessed semi-automatically by a rule basis. Here, generic interrelations funded on either physical fundamentals or working principles are recorded. By this approach, requirements structure matrices are derived semi-automatically. Combined with selecting critical requirements based on structured criterions, iterations due to changing requirements will be reduced.

In this paper, a novel approach towards risk classification of requirements of additively manufactured (AM) products is presented. The classification of an individual requirement is based on two aspects: a) influence factors implying dynamics of its specification and b) network indices quantifying the degree of cross-linkage with other requirements. Both aspects can indicate requirement changes. Influences on a requirement are assessed by a priority index based on criteria ‘uncertainty’, ‘dynamics’ and ‘relevance for product development’. Effects from other requirements are captured by network theoretical indices such as active and passive sum. In the end, requirements are classified accord-ing to their criticality. By this approach, requirements can be identified which might strongly affect the product development process of AM products.

By adding fibers to a polymer matrix, a reinforcement of the material can be achieved. Short fiber-reinforced polymers can easily be processed by the Fused Deposition Modeling (FDM) process without major modifications to the processing machine. For instance,short fiber-reinforced filaments can be processed to produce short fiber-reinforced components in the FDM process. In many other additive manufacturing processes this is not possible at this low cost. The choice of the matrix material, fiber type, fiber length and fiber orientation have a major influence on the properties of the produced component. In this paper, short fiber-reinforced filaments are processed by the FDM process. The processing properties and the resulting part properties are investigated with regard to fiber-specific influences. Additionally, the effects of different strand geometries and thus changed flow fields on the fiber orientation and mechanical part properties are investigated.

By adding fibers to a polymer matrix, a reinforcement of the material can be achieved. Short fiber-reinforced polymers can easily be processed by the Fused Deposition Modeling (FDM) process without major modifications to the processing machine. For instance, short fiber-reinforcedfilaments can be processed to produce short fiber-reinforced components in the FDM process. In many other additive manufacturing processes this is not possible at this low cost. The choice of the matrix material, fiber type, fiber length and fiber orientation have a major influence on the properties of the produced component. In this paper, short fiber-reinforced filaments are processed by the FDM process. The processing properties and the resulting part properties are investigatedwith regard to fiber-specific influences. Additionally, the effects of different strand geometries and thus changed flow fields on the fiber orientation and mechanical part properties are investigated.

The Fused Deposition Modeling (FDM) process by Stratasys is an additive manufacturing (AM) technique that can be used to produce complex thermoplastic parts without the need of a forming tool. A big challenge of this process is that there are several influencing factors with unknown effect on the resulting part properties. One of these factors is the layer time. The aim of this study is to examine the influence of the layer time on the resulting dimensional accuracy and mechanical properties of FDM components manufactured with the amorphous polymer ABS-M30. For this purpose a special job layout was designed to vary the layer time within a certain range. The investigations in this paper show a significant influence on the dimensional accuracy and also on the mechanical properties.

improved sensorless control of PMSM are pointed out. The

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.

Additive Manufacturing is a technology that offers a high potential forindustrial companies.Nevertheless, companies lack experience with this new technology and face the problem to identify processes where a successful and beneficial application can be achieved. They have to be supported in this analysis with a decision support tool which is capable to compare different manufacturing or repair approaches in order to determine the optimal solution for the correspondent use case. This is not always driven solely by costs but can also be critically affected by further influencing factors. This is why the decision support takes into account also time and quality alongside the costs. For a time-critical spare part supply, for example within aerospace sector, they are substantial for taking a decision. The presented decision support features a multi-attribute decision-making approach for selecting the most appropriate process, either Additive Manufacturing, conventional technologies or an external procurement.

Designing parts for additive manufacturing (AM) offers a broad range of geometrical and functional potentials. On the one hand the manufacturingtechnology offers the possibility of manufacturing highly complex freeform shapes, often referred to as bionic shapes. By use of these, perfect force fluxes without stress risings due to imperfect notches are realizable, getting the most value of used material. On the other hand these complex structures require a reliable geometry representation in compatible CAD-files. Conventional CAD systems were developed to generate geometries that are manufacturable with conventional machining. These are not capable of representing the high complex designs for AM. Especially for geometries generated by CAE like from topology optimization the conventional CAD systems fail to take advantage of the combination of CAE and AM. This paper explains why there is a lack of compatibility of well-known CAD systems with the potentials of AM. Therefore the AM-side of the problem is described by showing some potentials of AM and the need of high complex structures for this manufacturing technology. For the other side of the problem conventional methodologies for geometry representation of CAD systems are described and their limitations with regard to AM are worked out. Finally a voxel based geometry representation is presented as a solution for computer aided geometry generation of high complex AM–structures.

In many branches in the designengineerdepartment, product designs are just variations of existing parts. To bring the additive manufacturing technology closer to the Designer, it is necessary to show them which of their existing, conventionally manufactured parts can be produced with this technology. Apartselection methodology supportsdesigners in the decision whether a part is suitable for additive manufacturingor not. Due to the potential of the technology, which was especially seen in the aerospace industries, many criteria of the methodology were initially adapted for this industry. Furthermore the methodology is based on a quantified weighting system, which comes to a certain subjectivity. For future use, a development towards a less subjective methodology should be accomplished. Through a more detailed adaption for individual industries and a simplification of the input mode, the objectivity of the criteria can be increased. Likewise, the input time can be reduced by simplifying the questioning. A more efficient part selection will be achieved by a better weighting system.In the BMBF project “OptiAMix” this methodology is supposed to be further developed for highly different branches. By a better weighting system, the part selection will be more efficient. Therefore,the willingness for the use of the improved selection andfor the additive manufacturing technology will be increased.

Although infringements of intellectual properties in terms of product piracy are growing for years and threaten investments in research and development most companies still rely on legal measures like property rights. A more preventive effect to protect against counterfeits can be achieved using technical measures complicating reverse engineering, improving traceability and assuring data protection. Additive Manufacturing can contribute a lot to the effectivity and efficiency of those technical measures but presently they are often unconsidered during product development. To support decision makers and designers through all the steps of a product development process an integrated systematic approach has been developed. Protective measures using AM are allocated to specific process steps and responsible persons in charge so that the result is a guideline for “design for protection”. The main idea is to help developing piracy-robust products for that the return of investment is not threatened by counterfeits and its economical impacts.

In conventional manufacturing, ramp-up-management describes the planning and organization of the period between finished product development and the achievement of full production capacity for defined products. This classification has to be adapted and restructured by means of product independent and tool-free production in additive manufacturing. Therefore ramp-up-management already starts with decisions on the extentof the use of additive manufacturing, includes the building of technology-know-how as well as the technology integration into processes and infrastructure of the company and ends with the attainment of a sufficient process reliability for the AM-machine. This paper focuses on technology integration in processes and infrastructure, which is part of the German research project OptiAMix. In this project, new systems for process state analysis adapted to additive manufacturing and methods for the optimal integration of additive manufacturing are developed. Furthermore ways of using the synergies of existing infrastructures and new innovative production technologies are determined.

Designing parts for additive manufacturing (AM) offers a broad range of geometrical and functional potentials. On the one hand the manufacturingtechnology offers the possibility of manufacturing highly complex freeform shapes, often referred to as bionic shapes. By use of these, perfect force fluxes without stress risings due to imperfect notches are realizable, getting the most value of used material. On the other hand these complex structures require a reliable geometry representation in compatible CAD-files. Conventional CAD systems were developed to generate geometries that are manufacturable with conventional machining. These are not capable of representing the high complex designs for AM. Especially for geometries generated by CAE like from topology optimization the conventional CAD systems fail to take advantage of the combination of CAE and AM. This paper explains why there is a lack of compatibility of well-known CAD systems with the potentials of AM. Therefore the AM-side of the problem is described by showing some potentials of AM and the need of high complex structures for this manufacturing technology. For the other side of the problem conventional methodologies for geometry representation of CAD systems are described and their limitations with regard to AM are worked out. Finally a voxel based geometry representation is presented as a solution for computer aided geometry generation of high complex AM–structures.

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.

Compared to conventional polymer processing technologies the material selection in the Fused Deposition Modelling (FDM) process is restricted. To expand the range of materials the requirements for the material properties and the semi-finished products (filaments) must be clarified. For this, a machine- and process-independent rating of the processability is necessary. The established standards for the tensile strength test apply to specimens with nearly isotropic mechanical properties. The FDM process generates anisotropic parts. The properties are mainly influenced by the machine quality and the data processing. It is not possible to test a material for FDM independently of the machine and the data processing. In this paper, machine and process specific influences are investigated. Considering these influences, a custom-built specimen is created to test the tensile strength of the welding seams for polyamide 6. This procedure allows a machine- and process-independent rating of the processability in terms of tensile strength for different materials.

A widely used Additive Manufacturing (AM) technology is Fused Deposition Modeling (FDM) to create prototypes and end-use parts with close-to-production thermoplastics. For their use as a final product, it is necessary that additively manufactured parts strictly adhere to the geometrical requirements of the technical drawing. In this paper, the holes and cylinders of the cylindrical elements are investigated in terms of achievable geometrical accuracy. For this purpose, different test specimens that allow a measurement of inner and outer diameters from 3 to 80 mm were designed. All specimens were measured with a coordinate measuring machine (CMM) to evaluate deviations from the nominal dimension and form deviations. The measuring method includes a scanning of the surface to record the course of dimensional deviations over the diameter. Thus, it was possible to visualize how deviations on cylindrical elements manufactured in FDM occur. In order to counteract these deviations and to improve the dimensional accuracy, different shrink factors and filling patterns were investigated. Consequently, an improvement of the dimensional accuracy was achieved.

Fused Deposition Modeling (FDM) is an Additive Manufacturing (AM) technology which is used for prototypes, single-part-production and also small batch productions. For use as a final product, it is important that the parts have good mechanical properties, a high dimensional accuracy and smooth surfaces. The knowledge of the mechanical properties is very important for the design engineer when it comes to the component design. In this paper, investigations were conducted with the polymer ABS-M30 from Stratasys Inc. To achieve a quality improvement of FDM parts, various toolpath parameters and orientations were used. Within the mechanical properties, the tensile, flexural and impact strength were evaluated. Furthermore, the tensile strength of FDM parts is compared to injection molded specimens. With optimized parameters, an increase of the tensile strength by up to 28 % and a doubling of the impact strength were possible.

Die Zielsetzung beim Radfahren ist das Leistungspotential des Fahrers vollständig auszunutzen. Dabei muss das Fahrrad optimal an die Körpermaße des Fahrers angepasst werden. Besonders im Radrennsport ist neben dem hohen Leichtbaupotential eine aerodynamische Sitzhaltung von enormer Bedeutung. Unter Berücksichtigung dieser Anforderungen sind individuelle Bauteile und Strukturen zu entwickeln, da nicht in allen Fällen die Abmessungen der Standardbauteile eine optimale Anpassung zulassen. Im Hinblick auf einen groß gewachsenen Fahrer ist ein verlängerter Vorbau – Gabel-Lenker-Verbindung – für eine aerodynamische Sitzhaltung und somit einen geringen Luftwiderstand unumgänglich. Für die Herstellung solcher maßgeschneiderten Strukturen ist die additive Fertigung aufgrund der hohen gestalterischen Freiheiten und des hohen Individualisierungsgrades besonders geeignet. Im Rahmen dieses Beitrags wird ein Fahrradvorbau für einen überdurchschnittlich langen Fahrer festigkeits- und leichtbauoptimiert konstruiert und nach der Norm DIN EN ISO4210 unter Berücksichtigung der verfahrensspezifischen Randbedingungen beziehungsweise Gestaltungsrichtlinien des Laserstrahlschmelzens ausgelegt. Ausgangsbasis für die Geometriegestaltung sind die Grundlagen der Festigkeitsberechnung. Ein CAD-Modell wird erstellt und aufgrund der komplexen Belastungssituation mit Hilfe der Finite-Elemente-Methode numerisch untersucht sowie optimiert. Nach mehreren Iterationsschritten wird für den Werkstoff TiAl6V4 ein gewichtsreduzierter überlanger Fahrradvorbau von 140mm entwickelt und generativ hergestellt. Der anschließende Vergleich zu einem handelsüblichen Vorbau zeigt eine Gewichtsreduktion von ca. 30%.

manufacturing in electrical engineering applications.

The implementation of lattice structures into additive manufactured parts is an important method to decrease part weight maintaining a high specific payload. However, the manufacturability of lattice structures and mechanical properties for polymer laser sintering are quite unknown yet. To examine the manufacturability, sandwich structures with different cell types, cell sizes and lattice bar widths were designed, manufactured and evaluated. A decisive criterion is for example a sufficient powder removal. In a second step, manufacturable structures were analyzed using four-point-bending tests. Experimental data is compared to the density of the lattice structures and allows for a direct comparison of different cell types with varied geometrical attributes. The results of this work are guidelines for the design and dimensioning of laser sintered lattice structures.

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 processes offer great freedom in the design of components. This enables a high level of function integration. Also in terms of vibration damping, additive manufacturing yields opportunities for the selective implementation of damping functions due to their characteristics. In powder-based processes the disperse support material can be kept inside the cavities of the structure. This powder material can act as a particle damper. Due to the freedoms in design, the damping behavior can be adjusted selectively by varying the geometrical features of the cavities. Within this paper, investigations on the damping behavior of additive manufactured parts regarding free bending vibrations are focused.

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.

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.

The spare part industry in aerospace is highly demanding. For conventional manufacturing technologies it is difficult to meet these requirements. In contrast to that, the design freedom of Additive Manufacturing enables the production of complex and lightweight parts. The lack of experience with this technology hampers the decision where Additive Manufacturing can be economically applied. The cost drivers have to be newly evaluated and holistically investigated. Supply chain advantages have to be considered during the decision process, too. Therefore, aerospace characteristics are analyzed within the paper and a methodology based on Multi Attribute Decision Making (MADM) is introduced. To do so, the cost appraisal for Additive Manufacturing has to be detailed. Additionally, changes in the supply chain have to be identified and quantified. Quality criteria have to be taken into account as well. In the end it is shown how these influence factors can be combined to create a decision support.

Additive Manufacturing offers a great potential for the optimization of products. Therefore different approaches are feasible to exploit these potentials for elaborating optimal solutions. For example these include optimization of weight or stiffness of structural components as well as the integration of functions and other entities of assemblies. Note, however, that additive manufacturing processes have process specific limitations. Products, components and assemblies, as well as procedures for the design and production preparation must be optimized with regard to a successful additive manufacturing. The use of already known tools for the optimization and design needs to be reconsidered and adapted to theadditive manufacturing. This also includes the production planning with component orientation in build chamber as well as a necessary quality management system. This paper shows several ways for product optimization with additive manufacturing, often based on topology optimization, and procedures for information gathering, decision making and shape determination for part optimization for Additive Manufacturing.

Additive manufacturing offers advantages for the production of a final product. Nowadays still many companies have not integrated this new technology into their product development processes (PDP). This paper will discuss additive manufacturing with regards to the current available PDP's while setting a focus on the economic aspects of the integration. Based on a sample part several tools will be discusses which may be uses in the different phases of product development. These tools aim on the simplification of integrating additive manufacturing technologies into existing PDP's. Included are methods for early and accurate cost estimation as well as product selection processes, best practice templates for creating knowledge and process awareness.

Nowadays, the material efficiency and part reliability are two majorissues in product development. Thus a product optimization often requires complex structures that are hard to be manufactured conventionally. Additive Manufacturing (AM) however offers great potentials for producing complex shaped parts economically. Different approaches are feasible to exploit these potentials based on the part’s application from shape optimization of structural components to the integration of functions and other entities of assemblies. Several parameters are defined that influence the costs and quality of the future product and carefully have to be balanced. To do so, the use of already known tools for the optimization and design needs to be reconsidered and adapted to the special characteristics of AM. As not all optimization potentials can be realized perfectly, a decision methodology is required to obtain the relevant potentials and to get to a trade-off between all requirements including the ecological impact. The paper shows different approaches for product optimization with AM and procedures for decision making in order to get to the optimal solution.

Additive Fertigungsverfahren bieten in der Luftfahrtindustrie großes Potential. Die Geometriefreiheit ermöglicht die Produktion von komplexen und gewichtsoptimierten Bauteilen. Die mangelnde Erfahrung der Unternehmen mit dieser Fertigungstechnologie erschwert jedoch die Entscheidung, an welcher Stelle Additive Manufacturing ökonomisch sinnvoll eingesetzt werden kann. Die Kosteneinflussfaktoren unterscheiden sich an vielen Stellen von denen traditioneller Fertigungsverfahren und müssen gänzlich neu bewertet und eingeordnet werden. Dabei verlagert sich auch der Fokus weg von den reinen Herstellkosten hinzu einer ganzheitlichen Kostenbetrachtung. Wesentliche Vorteile lassen sich auch meist in der Supply Chain erzielen und müssen im Zuge des Entscheidungsprozesses für ein Fertigungsverfahren bei einem bestimmten Bauteil berücksichtigt werden. Daher werden in der Präsentation die Charakteristika der Luftfahrt analysiert und die Methodik einer Entscheidungsunterstützung vorgestellt. Im Zuge dessen gilt es die Kostenbewertung additiver Fertigungsverfahren näher zu beleuchten, um die Fertigungs- bzw. Reperaturkosten mit traditionellen Verfahren vergleichen zu können. Weiterhin müssen Veränderungen in der Supply Chain identifiziert und bewertbar gemacht werden. Qualitätskriterien müssen ebenfalls mit in die Betrachtung einbezogen werden. Anschließend wird aufgeziegt wie diese Einflussfaktoren in die Entscheidungsunterstützung integriert sind.

The paper gives an overview of actually used Additive Manufacturing (AM) data formats and AM data infrastructure. Based on empirical analysis of the actual situation, necessary improvement of data management and exchange formats in context with AM technology is derived. The purpose of this paper is to understand the actual use of data formats and management in the field of AM. The paper draws conclusions based on an empirical analysis of the used data formats dependent on stakeholder groups. The results of the expert survey show a necessity to improve or develop new AM specific data formats.

The mechanical characterization of fused deposition modeling (FDM) parts is mostly done by static tests. In many applications, parts are also dynamically loaded. Here, fatigue tests can help to identify the expected lifetime of a part. This article discusses the fatigue behavior of FDM specimens manufactured with Ultem 9085. For this, tensile bars are manufactured according to ASTM D638 in different build orientations. Tests are performed in a range of pulsating tensile stresses, and S-N curves are documented for different build orientations. For higher loads, the FDM anisotropy characterizes the lifetime of used specimens, which is similar to static tensile bars. For lower loads, including a higher number of cycles to failure, S-N curves of different build orientations converge. In further tests, tensile bars were chemically smoothed with chloroform vapor. Chemical smoothing reduces surface roughness and increases tensile strength of specimens in the upright build direction. Fatigue tests of chemically treated specimens show no significant lifetime increase.

The material Ultem 9085 is a flame-retardant thermoplastic polymer, which can be processed with Fused Deposition Modeling (FDM). Due to ist high strength-to-weight ratio and FST rating, Ultem 9085 parts are used in aviation. Process related staircase effects on rounded and slanting part areas require a surface treatment for end use parts. These processes include smoothing by mass finishing or coating in order to reduce surface roughness. An alternative smoothing technique is chemical surface treatment, such as the use of Acetone for ABS materials. In this paper, the surface of Ultem 9085 parts is treated with Chloroform vapor in order to solve material at the surface and smooth it. Therefore, specimens built in different build orientations are treated and tested with regard to surface roughness values and mechancial strength properties. The analysis of surface roughness and treatment time shows a significantly higher efficiency for chemical treatment in comparison to mass finishing. By employing chemical treatment, it is possible to reduce surface roughness by more than 80 % to Rz values of approximately 15 µm. Mechanical tests and measurements of the Melt Volume Rate (MVR) show no material destruction for chemical surface treatment at room temperature for less than 150 min.