DMRC Projects 2022
Specimens made according to standards, such as DIN or ISO, are usually used to evaluate and to compare material properties.
The focus of the project is to investigate if material properties determined by tensile test, fatigue test, and fatigue crack growth
test are affected by shape, size, and surface roughness of the used specimens. The materials examined areX2CrNiMo17-12-2
(1.4404) and AlSi10Mg (3.2382), both commonly used in industry.
In research projects, an immense number of test specimens and other experimental setups are built. Reliably tracking these construction jobs, their properties, and parameters in the later course of a project means a large manual effort for the researchers. Project RAMSRApp supports the DMRC and its researchers in a more effi cient realization of its projects.
Multi-laser systems are intended to make powder-based laser beam melting more cost-effective, and thus more attractive for industrial applications and serial production. Current multi-laser systems operate with up to twelve lasers. With an increasing number of lasers in use, higher productivity can be achieved. However, the challenges are in determining of suitable exposure strategies and an optimal working fi eld for each laser. Thus, the quality and properties of the parts are ensured and, at the same time, the effi ciency of the process is increased. The DMRC is investigating different process strategies that should be applied to different multi-laser systems to identify their infl uence on the resulting material properties.
This project answers the question of the extent to which the inert gases used in the additive manufacturing process, as well as the gases introduced by the manufactured material, affect the material properties. Particular attention is devoted to the influence of hydrogen, oxygen and nitrogen.
Our ambition is to bring the “Sustainability of Additive Manufacturing” into the spotlight. We build upon a generic Product Life Cycle (PLC) model and deepen that for a holistic sustainability analysis of the AM process. This approach enables us to quantify the correlation of the actual AM process with conventional alternatives in terms of Life Cycle Assessments and Costing (LCA and LCC). As a prerequisite, a gap-free and consistent database is required to both quantify the costs to ecological and economical side by side and quantify sustainability. The main contribution of the project lies in the identifi cation of required attributes, the assessment of available data quality and detection of data gaps.
Additive Manufacturing components with large dimensions are required for many applications in the industry, and this quickly exceeds the given build volume. However, additive manufacturing systems designed specifically for large-format components are available on the market. In this project, the focus is on large format FDM systems. It is known that with the material PLA Large Format FDM systems achieve good component qualities, but the material is not suitable for many applications. In the context of this project it should be examined whether an engineering polymer can be processed on a large format FDM printer to a dimensionally stable and reproducible component.to a dimensionally stable and reproducible component.
In recent years, selective laser sintering has evolved from a rapid prototyping technology to a process for the direct production of sophisticated plastic components. In this context, the functional and mechanical properties of additively manufactured components are becoming increasingly important. However, there currently is only a limited selection of LS materials available, meaning that not all customer-specific requirements can be met. Particularly in the automotive and aerospace industries, filled plastics represent standard materials, as they can exhibit better mechanical properties, higher heat resistance or improved wear properties, depending on the filler. Therefore, filled laser sintering materials are currently being investigated at the DMRC.
Halogenated or none refreshable fl ame retardant laser sintering materials are state of the art. Those material have the drawback of hazardous or sustainability issues, which often prevent a successful business case. The overall objective is the deployment of a fl ame retardant laser sintering material that does not contain halogens and still allows a proper recycling rate for sustainable and cost effi cient applications. For this purpose, the ageing mechanisms preventing the recycling of currently available halogen-free fl ame retardant materials will be done. In Addition, a screening of different fl ame retardants shall lay down the foundations for an actual material development in a follow-up project.
DMRC Projects 2020/2021
The processing of soft materials in the FDM process brings new challanges for the process execution. Studies have already shown that the definition of the process parameters and, above all, the existing design limitations do not necessarily correspond to those of the processing of typical FDM polymers. Reasons for this are the soft elastic behavior of the deposited strands as well as the material behavior before and inside the extrusion head. This project identifies and improves the process limitations by selecting suitable geometries. At the same time, the process parameters are also adapted to the processing of a soft FDM material. Based on this, a procedure will be developed with which a material- and machine-independent improvement of the processing of TPU in FDM can be achieved.
To enable the use of AM in broad industrial practice, specific tools are required. Function-orientated active principles are a proven tool in the design process to find solutions. Within the project corresponding active principles are developed, especially for AM, and verified on demonstrators and applications. The potential of a function-orientated AM-design is illustrated and examined on industrial applications. In 2017, the focus was on the topics “heat transfer” and “structural optimization”. The project framework was continued 2018 with the topics “Magnetic Flux Guidance” and “Structural Damping”. For 2019, the project focus is on “Embedded Sensors” to implement certain sensors within components that are manufactured in the Laser Beam Melting process (LBM).
Additive Manufacturing (AM) is a technology enabling the engineers to increase the function and efficiency of designs. The idea of this project is to develop generic design studies that are relevant to the members´ application needs, run analysis, collect performance data and report the benefits. Thus, the project idea is adapted year by year with facing new challenges or harnessing further potentials of AM. This year the project considers hydraulic- and pneumatic powder bed AM parts and assemblies. General feasibility and limitations in design and manufacturing for hydraulic or pneumatic parts shall be analyzed for Polymer Laser Sintering and Selective Laser Melting as well.
Design rules for additive manufacturing (AM) processes are important for the acceptance of these technologies and are required by the industry. Furthermore, design rules are necessary to provide and teach the design freedoms of AM to users of these technologies as well as to students. The project “Updated and Extended DMRC Design Rule Catalogue – DMDR 3.0” is aimed to extend the exisiting DMRC Design rule catalogue by six machine-material-parameter-combinations of the participating industry partners.
Defects such as porosity are more commonly encountered in as-built Additive Manufacturing (AM) parts than in wrought alloys and some defects, such as trapped powder or lack of fusion etc., are unique to the DMLM process. Process-specific defects that can be produced during the generation need to be characterized using destructive and non-destructive evaluation methods, as there are no established standards. Consequently there is a lack of effect-of-defect data for AM parts, which hinders part acceptance. Developing a catalogue of defects commonly encountered in the L-PBF process, and categorizing the critical defect types, sizes and distributions is critical for establishing acceptance criteria.
Defects such as porosity are more commonly encountered in as-built Additive Manufacturing (AM) parts than in wrought alloys and some defects, such as trapped powder or lack of fusion etc., are unique to the PBF-LB/M process. Process-specific defects that can be produced during the generation need to be characterized using destructive and non-destructive evaluation methods, as there are no established standards. Consequently, there is a lack of effect-of-defect data for AM parts, which hinders part acceptance. Developing a catalogue of defects commonly encountered in the PBF-LB/M process, and categorizing the critical defect types, sizes and distributions is critical for establishing acceptance criteria.
In recent years, selective laser sintering has evolved from a rapid prototyping technology to a process for the direct series production of sophisticated plastic components. In this context, the functional and mechanical properties of additively manufactured components are becoming increasingly important. However, there currently is only a limited selection of LS materials available, meaning that not all customer-specific requirements can be met. Particularly in the automotive and aerospace industries, filled plastics represent standard materials, as they can exhibit better mechanical properties, higher heat resistance or improved wear properties, depending on the filler.
Metallic additive manufactured components can be produced with the Fused Deposition Modeling (FDM) process using polymer filaments that are filled with metal particles. In accordance to the conventional MIM (Metal Injection Molding) process, the FDM process is used to manufacture green parts. The polymer is then removed from these green parts in post-treatment steps to create brown parts. Finally, the brown parts with the metal particles are sintered to create the final components. This project deals with this topic and investigates necessary processing parameters along the process chain and demonstrates achievable component properties.
Additively manufactured metal components are increasingly used in the industrial environment for the production of complex component geometries, small series or individualized products. A comparatively new approach for the production of metal components is the use of the Fused Deposition Modeling (FDM) process, in which a polymer filament filled with metal powder is used. In accordance to the conventional Metal Injection Molding (MIM) process, the polymer is removed from the manufactured part (green part) in a post-treatment step (brown part). Afterwards, the metal particles are sintered (final part). This project investigates the processing of a suitable support material. For this purpose, both the processing parameters and the process steps are considered.
A promising remedy to avoid undesired macro-cracking of hard to weld materials during SLM processing is a build chamber pre-heating system. The increased powder bed temperature reduces cooling rates as well as residual stresses. In this project, a in-house developed build chamber pre-heating system is utilized to process the titanium alloy Ti64 and the titanium-aluminide alloy Ti-48Al-2Cr-2Nb. In addition to the high proceseing temperatures up to 800°C, a gas purification system will be integrated in the SLM Solutions 280 machine in order to reduce residual oxygen content.
Current developments in the field of materials create new potential for the use of the additive manufacturing process Digital Light Processing (DLP) or similar processes on the basis of vat-photopolymerization. Previously existing weak points, such as brittle components or low UV resistance, are no longer present due to the new materials. Therefore, the suitability of this process for manufacturing end products is increasing. Many new opportunities are emerging, which create a great need for research in this area. For this reason, the DMRC starts with the research of the DLP process and the material properties.
Most of the modern Polymer Lasersintering machines are not equipped with relaiable and automated process monitoring systems. Still the process monitoring is a very critical aspect for serial production, as even small coating errors can lead to part failure. The objective of this project is to design and implement a retrofittable monitoring system for the EOS P3 platform, which is capable to detect false powder spread, the recoater filling level and inform the operater, if an event has been detected.
So far, just a fraction of steels and metallic alloys conventionally available are processible via selective laser melting (SLM) in a defect free fashion. Weldable metallic alloys can be SLM processed defect free without severe process or alloy modifications. Still, processing parameters must be developed, and material properties must be characterized for the SLM materials. Thus, in this project, three weldable materials are investigated in order to expand the material spectrum in the field of SLM. Microstructural and mechanichal properties are determined for the martensitic tool steel W360, ths quench and tempering steel 36NiCrMo16, and the cobalt-base alloy Ultimet.
Additive Manufacturing (AM) technologies have a significant potential for the production of individual parts with high complexity and high design freedom. This technology is already widely used, especially in the areas of biomechanics, for example, to produce individual, patient-specific prostheses, in the aerospace area to produce structurally optimized brackets, in the field of passenger services and in the automotive industry. However, the number of possible materials is limited. The materials typically used are TiAl6V4, 316L, Inconel and AlSi10Mg.
The introduction of the selective laser sintering (SLS) process into the market of the direct manufacturing of components demands materials which meet the high requirements of the industry. PA613, a polyamide developed by Evonik to be used in high temperature applications for example in automotive or electronic industry, is tailored to the SLS process. Especially for these applications the long-term properties are of high importance and are investigated within the described project. In previous projects the material PA613 showed good processability on an EOS P396 laser sintering system and process parameters which result in high part quality were found. Together with determined short term properties the material can be classified within the range of high performance polymers.
A widespread additive manufacturing process is the Fused Deposition Modeling (FDM). Not many high performance polymeres are available. In theory, it is possible to process any thermoplastic polymer using the FDM process. For professional FDM machines, only a small number of different materials can be purchased. These materials are provided by the machine manufacturers and the material properties are often not sufficiently known. Therefore, this project investigates the processability of alternative high-performance polymers for the FDM process with regard to the warpage behavior.
The qualification of new polymers for the FDM process, using known material data, is not practicable and the qualification of processing are conducted experimentally. During the qualification process of a new material, further material properties must be considered in addition to the general processability in the FDM process. In a previous DMRC project in 2018 it was investigated which alternative high-performance plastics can be processed in general. After the general processability of the materials was examined the achievable weld seam strength was determined. In the subsequent project in 2019 the shrinkage and warpage behavior was studied. In this project, fully developed FDM process parameters are generated, based on the basic parameters defined in the previous projects.
Many different processes are established in Additive Manufacturing (AM). The processes differ from each other in a number of points, partially significantly, such as the required support, build-up rates, resolution, material variety, anisotropy, repeatability, surface roughness, investment costs and much more. These many differences make it difficult to compare the processes and to select a suitable process for a component. In this project, the polymer-based AM will be compared comprehensively and the advantages and disadvantages will be worked out. Based on this, a tool will be developed to support the process selection. This is intended to support persons with no experience in AM as well as those with a great know-how.
One of the biggest advantages of Metal AM is the ability to produce complex internal structures, cavities and freeform geometries. Surface finish and tolerances of as-print parts often don’t meet the criteria of technical applications. Therefore, additional processes are necessary. The conventional processing of such surfaces and structures can only be realized with very great effort, if at all. This is true for all metal AM processes. For this reason, the need of surface finish, support and powder particle removal is necessary for every component. Right now, the ability of surface finish often limits the AM-design because surface have to be attainable for conventional processes.
Additive manufacturing (AM) is gradually establishing itself in the production of complex-structured components. Beyond the utility value of design freedom, the target-effective use of materials in a relatively short time is decisive. Dynamic material loads correspond to the reality-oriented use case and are strongly affected by the surface topology. In particular, the nickel-based alloy Inconel 718 is primarily used in propulsion technology and is therefore subject to a relatively frequent peak load within the product life cycle. Synergetically, a next step includes the identification of a cost-efficient post-processing with increased build-up rate.