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The following projects are currently being worked on as part of our research focus "Additive Manufacturing":

LuFo V-3 cooperative research project „Development of additive manufactured integral structure parts”

Subproject: Mechanical machining of CMT-welded parts

This subproject focuses on the mechanical machining related effects on the size and shape changes as well as material properties of CMT deposition welded parts for aerospace applications. The cold metal transfer process is still a welding process with high thermal impact, despite the term “cold”. As a consequence thermal stresses can cause significant part distortion during machining or distortion requires large tolerances. Since CMT structures have a comparably rough surface structure eventually all-side machining is required. The aim of this project is to determine suitable machining parameters on one hand and to master the distortion behavior of CMT-welded parts made e.g. of TiAl6V4 in combination with the influence of the machining process on the other. The size and shape deviations as well as residual stress distributions of CMT / plate hybrid structures serve as input properties for a simulation-based analysis of the impact of the machining process.

Editing: FT

Funding: BMBF LuFo V3

Contact:
Dr.-Ing. Rüdiger Rentsch
Telefon. +49421 218 51191
E-Mail: rentsch(at)lfm.uni-bremen.de

BMWi AIF ZIM project „Development of additive manufactured Aluminum bearings with hard-particle reinforced raceway”

In this collaborative research project the aim is to utilize the laser metal deposition (LMD) process to generate large Aluminum roller bearings and/or bearing houses directly rather than following standard casting process routes.

To manufacture bearing house blanks flexibly in-house it could help to reduce significantly lead-times for single part or small batch production of lightweight, large-size bearings. By additionally reinforcing the Aluminum surface using hard spherical fused tungsten carbide particles (SFTC) the printed surfaces could directly be used as roller raceways and thereby further increasing lightweight capability. The BIAS GmbH, the IBO GmbH and the Leibniz-IWT are collaborating on developing this additive manufacturing technology. The Leibniz-IWT machines the blanks to size and will analyze those with particles regarding their tribological interaction with bearing rollers. It is expected that distortion engineering is required when scaling up the LMD to larger bearings and adding the reinforcement. 

Editing: FT, BIAS GmbH, IBO GmbH

Funding: BMWi AIF ZIM 

Contact:
Dr.-Ing. Rüdiger Rentsch
Telefon. +49421 218 51191
E-Mail: rentsch(at)lfm.uni-bremen.de

RobustAM - Robust and efficient processes for laser additive manufacturing

The objective of the project is to reduce the variability of quality-relevant product parameters (e.g. porosity) in laser additive manufacturing of metallic components.

Using the example of a Ti6Al4V component, it is to be demonstrated that the component service life can be significantly improved compared to the state of the art through appropriate understanding of the interactions and further development of the individual process steps, as well as improved process monitoring. In this way, the required testing effort should be reduced in the medium term and ideally only carried out selectively. Therefore, the data quality from the processes, a deeper understanding of the cross-process step interactions and the effects of defects on the component lifetime will be investigated.

Editing: WT-LW, AKON Robotics, AMSIS GmbH, BIAS GmbH, Materialise GmbH, Testia GmbH

Associated partner: Airbus Operations GmbH

Funding: EFRE-LURAFO3001C

Duration: 15.04.2020 until 31.03.2022

Contact:
Dr.-Ing. Christian Werner
Telefon: +49421 218 51354
E-Mail: werner(at)iwt-bremen.de

                  

SPP2122 Materials for Additive Manufacturing

Qualification of new steel-alloying strategies for LAM powders by combined in-situ additivation, agglomeration and in-/post-process treatment

The main objective of Priority Programme 2122, funded by the German Research Foundation (DFG), is the synthesis of new metal and polymer powders for efficient laser-based additive manufacturing through formulations, additivation and (chemical) modification of new and commercial powders. This should significantly expand the choice for powder materials accessible to laser-based additive manufacturing (LAM). Improving processability includes requirements such as efficient, low-cycle, highly reproducible and precise laser-based additive manufacturing processes.

One of the eleven sub-projects is the tandem project "Qualification of new steel-alloying strategies for LAM powders by combined in-situ additivation, agglomeration and in-/post-process treatment" in cooperation of the Leibniz Institute for Materials Oriented Technologies - IWT with the University of Bochum - Chair of Materials Technology (LWT) and the University of Dortmund - Department of Materials Testing Technology (WPT). The main objective of the project is the development of new starting materials for additive manufacturing and their qualification for the processing of martensitic, hardenable tool steels or cast iron by LAM.

By mixing iron and ferroalloy powders, the content of certain elements such as Cr, Mn, Ni is to be increased in order to produce, for example, white cast iron and ledeburitic cold work steels. Mixtures of ferroalloy powders and pure elements, which are conditioned by agglomeration into flowable powders, are also to be processed in a similar way. It is assumed that similar alloys or chemical compositions, despite the different processing routes, can achieve equivalent properties of the powders.

This would mean that only a few base powders with different chemical compositions are needed to produce several alloys. Laser-based additive manufacturing can significantly accelerate the development of new alloys due to economic and procedural advantages, as the microstructure formation process and the associated formation of internal defects can be decoupled from the LAM densification process.

To deal with the complex material-oriented research within SPP 2122, all aspects are addressed in a holistic approach regarding powder production, conditioning and processing (IWT), alloy design and microstructure investigation of the designed powders (LWT) as well as microstructural, micro-magnetic and mechanical characterisation of the SLM components (WPT).

Further information on the sub-project or the overall project SPP 2122 can be found here.

One of the publications on the project can be found here.

Contact:
M.Sc. Anna Strauch
Phone: +49421 218 51327
E-mail: strauch(at)iwt-bremen.de

 

SupStruct3D - Phenomenological Model Calibration for the Automatic Generation of Optimised Support Structures for Laser Additive Manufacturing

The aim of the joint project is to develop a tool that enables these support structures to be generated fully automatically and optimised for each construction process in order to reduce process time, material and post-processing effort.

This is because components that are laser-additively produced from metal powder usually have to be stabilised during the construction job by so-called support structures.

For this purpose, a test specimen development is first necessary, which ensures that the specimens always fail in the area of the support structure (not in the overhang to the clamping area of the tensile testing machine) and are tested in a non-preloaded state. The subsequent mechanical characterisation of varying support structure is incorporated into an extended material model. With the help of a few printed calibration samples, the support optimisation module can then make it possible to generate the optimal support structure without lengthy tests.

Editing: IWT-WT-LW

Funding: EFRE-FUE0616B

Cooperation partner: Additive Works GmbH

Contact:
M.Sc. Lena Heemann
Tel.: +49421 218 51414
E-Mail: heemann(at)iwt-bremen.de

N-alloyed, stainless steels for additive manufacturing using L-PBF (AddFeN II)

The goal of the renewal proposal is to give a deeper understanding of the microstructure formation mechanisms and the associated properties of nitrogen-alloyed austenitic stainless steels and duplex steels processed by L-PBF.

The powder production, L-PBF processing of the powders, post processing as well as characterization of the resulting microstructures and the mechanical and chemical properties are carried out. In particular, the interactions between single powder particles during flowing of the powder are used to interpret the global powder properties and are correlated to the powder production and conditioning parameters. The solidification sequences of the nitrogen-alloyed stainless steels depending on their chromium and nickel equivalents are of special interest considering the process specific thermal conditions during L-PBF.

Editing: IWT-VT, IWT-WT, RUB, TU Dortmund University

Funding: DFG UH 77/12-2

Contact:
Dr. Chengsong Cui
Tel.: +49421 218 51404
E-Mail: cscui(at)iwt-bremen.de

Laser beam melting of amorphous metal powders - LaSaM

The LaSaM project intends to broaden the production of bulk metallic glasses (BMGs) by laser beam melting (LPBF) and expand their economic applicability.

The greatest challenge is to avoid crystallization along the entire process chain from powder production to use in LPBF to maintain the superior properties of BMGs. The main goal is to produce amorphous components made of CuTi-based alloys by LPBF and to gain knowledge about the oxygen intake and cooling behaviour taking place during the process, as they could lead to crystallization. This will allow extending the narrow process windows for defect-free processing and the adaptation of the technology to new product geometries. The project is a cooperation with the University of Saarland and the University of Duisburg-Essen.

Editing: IWT-VT

Funding IGF No.: 21227 N

Contact:
M.Sc. Erika Soares Barreto
Tel.: +49421 218 51404
E-Mail: sbarreto(at)iwt.uni-bremen.de

Pegasus - Development of a pressure gas atomization process for a cost and material efficient production of aluminum alloy powder for additive manufacturing

Within the project “Pegasus” a novel pressure-gas-atomization process (PGA) will be developed to significantly increase the cost and material efficiency in the production and processing of aluminum powders. 

The potentially narrower particle size distribution of powders produced by PGA increases material efficiency and could thus create both ecological and economic advantages compared to conventional technology. In order to evaluate these effects, the produced aluminum alloys will be investigated with respect to their suitability for additive manufacturing. The focus is mainly on the characterization and processing of temperature sensitive powder alloys.

Editing: IWT-VT / WT

Funding: BMWI-AiF/ZIM

Contact:
M.Sc. Marcel Hesselmann
Tel.: 0421 218-64549
E-Mail: hesselmann(at)iwt-bremen.de

GenMat3D – Generation of tailored material properties by selective laser beam melting for launcher structures

The overall aim of the GenMat3D project is the development of a new type of process control for laser powder bed fusion (LPBF), which enables the production of components with material properties tailored to the specific requirements.

Such a process control could be used in integrally printed large bionic structures in the aerospace industry. By applying local gradation, adapted to the requirements, the aim is to decrease production times while optimizing the weight of the components at the same time. To make this possible, correlations between the process parameters and the resulting component properties must be determined. Especially on the microscale there is no sufficient knowledge about the influence of component temperature and geometry on the material properties.

Editing: WT-LW, Ariane Group GmbH, Materialise GmbH, Reiner Seefried GmbH

Funding: EFRE_LURAFO2002A

Duration: 04/2019 - 12/2021

Contact:
M.Sc. Daniel Knoop
Tel.: +49421 218 51435
E-Mail: dknoop(at)iwt-bremen.de

PORE-Ti - Machining optimized printing of Ti6Al4V components for composite parts with CFRP

The aim of this project is the production and machining of titanium-CFRP composite components whose titanium component is produced by selective laser melting.

The aim is to investigate whether the machining properties of the titanium-CFRP composite component can be positively influenced by introducing pores into the titanium. The focus is also on the potential for optimising the geometry of drilling and milling tools.
Additively manufactured components are usually produced close to the final contour. However, it is not always possible to do without machining, especially if the printed component is further processed into a composite component with a fibre composite material. This places special demands on the production process and tools, especially when combining titanium and CFRP.
Titanium is considered to be a difficult material to machine, with significantly higher forces acting on the cutting edge than is the case with CFRP. Therefore, tools for machining titanium are provided with a defined cutting edge rounding to prevent cutting edge chipping. With CFRP, however, this rounding leads to increased delamination or reamed bore walls. This poses a continuing challenge for the machining of titanium CFRP composites.

Editing: IWT-WT/ IWT-FT/Isemann

Funding: EFRE_LURAFO

Contact:
Dipl.-Ing. Annika Repenning
Tel.: +49421 218 51492
E-Mail: repenning(at)iwt-bremen.de

ProAM - From powder to component

Establishment of a continuous process chain for the additive manufacturing of highly stressed metallic components

As part of the "ProAM" project, a complete process chain for the additive manufacturing of high-strength metallic components is being set up at the IWT (see Figure 1). The aim is to cover the entire spectrum from powder production to manufacturing and quality assurance. This closed process chain represents a unique selling point of the IWT, also in national and international comparison. The cross-process chain consideration of the production of highly stressed metallic components has been a central element of the IWT's research strategy for many years. This is now transferred to the process chain of additive manufacturing. As an advantage, the broad infrastructure and expertise already available at the IWT is accessible.

Structural analysis with xenon plasma FIB-REM

To expand the analysis, a focused ion beam/scanning electron microscope (FIB-REM) was procured, which enables a high-resolution, three-dimensional material and structure analysis down to local residual stresses (Figure 2).

Hybrid production using cold gas spraying and 5-axis milling

To expand the manufacturing possibilities, a hybrid manufacturing cell was set up with funds from the ProAM project. This consists of a spray booth for the additive application of metal powder by means of cold gas spraying and a 5-axis milling machine. Using a common workpiece interface (hydraulic clamping system), components can be processed sequentially and iteratively both additively and subtractively with the help of this system (Figure 3).

Contact:

Dr.-Ing. Andree Irretier
Phone: +49421 53708 12
E-mail: irretier(at)mpa-bremen.de

Dr.-Ing. Kerstin Hantzsche
Phone: +49421 218 51430
E-mail: hantzsche(at)iwt-bremen.de

Dr.-Ing. Lars Schönemann
Phone: +49 421 218-51142
E-mail: schoenemann(at)iwt.uni-bremen.de

 "From Powder to Component - ProAM" was funded by the European Union with the following objective: "Strengthening a specialised, company-oriented innovation system" and is thus part of the ERDF Programme Bremen 2014-2020.

Duration: January 2018 until the end of 2021

More information: www.efre-bremen.de