In the department Cutting and Mechanical Surface Treatment, basic research as well as application-oriented research and development is carried out on the classical cutting production processes with geometrically determined cutting edges, such as turning, drilling and milling, and on hardening processes, such as deep rolling and shot peening.
A broad spectrum of tasks is being worked on in individual projects, bilateral projects and joint projects. In addition to the development and optimization of tools and processes, one of the core tasks is the investigation of fundamental mechanisms of action when using geometrically defined processes for machining mainly metallic high-performance materials and fiber-reinforced composite materials.
Classical machinability analyses are as much a part of the portfolio of the work as the clarification of complex questions concerning the influence of geometrically determined processes on peripheral zones. The modelling and simulation of manufacturing processes is an integral part of the work, especially in basic research. The department is equipped with state-of-the-art machine tools, powerful process measurement technology, excellently equipped laboratories and extensive computer and simulation capacities.
These include, among others:
Basic research projects aim primarily at analysing and understanding essential physical mechanisms of the manufacturing processes used through systematic studies. Frequently, the mechanisms are mapped in mathematical models in order to be able to predictively optimize manufacturing processes or shorten the optimization process in industrial practice. Different metallic materials and fibre-reinforced composites are considered in a case-specific way. Basic research is predominantly carried out in publicly funded research projects, e.g. by the German Research Foundation (DFG) or the German Federation of Industrial Research Associations (AiF).
A main research focus in the technological areas of the department is the targeted influencing of peripheral zones by geometrically determined manufacturing processes with special consideration of the achievable productivity and component quality. The effects occurring in the manufacturing process on the processed material (mechanical, thermal, chemical as well as combinations thereof) are determined metrologically and/or by simulations and their effect on the resulting marginal zone properties is systematically investigated. On the basis of these quantitative correlations, it is possible to adjust the properties of peripheral zones in a knowledge-based and thus more targeted manner than before by means of manufacturing processes.
Further questions, which are dealt with in the basic research of the department, concern the heat distribution in geometrically determined machining processes, the development and minimization of component distortion due to process- and clamping-related residual stresses as well as the interlinking of individual processes, for example for the production of drive components, in cooperation with other departments of the institute. For example, by using the finite element method in chip formation simulations, the physical causes of material changes, such as the development of residual stresses or material damage caused by process-related temperatures and stresses in the processed material, can be analysed and better understood in a more targeted manner than is often possible on the basis of measurements. In addition, analytical models are also developed in the department, which allow a better insight into the relevance of individual parameters for a manufacturing process and a faster calculation than numerical approaches.
In addition to projects in basic research, the department Cutting and Mechanical Surface Treatment is working on application-oriented research and development projects, mostly in bilateral cooperation. Among other things, the work deals with the development and optimization of tools and processes and the performance of machinability analyses. In addition, comparative analyses are also carried out within the framework of benchmarking studies.
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.
This project was funded by the European Regional Development Fund (ERDF).
Editing: IWT-WT/ IWT-FT/Isemann
Funding: EFRE_LURAFO
This project is part of the research focus "Additive Manufacturing" at IWT Bremen.
Contact:
Dipl.-Ing. Annika Repenning
Tel.: +49421 218 51150
E-Mail: repenning@iwt-bremen.de
Tobias Kinner-Becker
Tel.: +49421 218 51492
E-Mail: kinner-becker(at)iwt-bremen.de
The objective of the research project is to develop and evaluate new, environmentally friendly hydraulic fluids based on highly biodegradable polysaccharides from the renewable raw material macroalgae.
Extensive tribology tests on polysaccharide-based fluids of different concentrations conducted on a cross-cylinder-tester helped to evaluate their suitability. By adding a lubrication additive (< 2 % in volume), comparable results to conventional hydraulic oils were achieved. In future, these fluids will be tested on a hydraulic unit for their mechanical stability.
Cooperation: Hochschule Bremen
Funding: BAB
Contact:
Dr.-Ing. Jens Sölter
Tel.: +49 421 218 51187
E-Mail: soelter@iwt.uni-bremen.de
Objective of the transfer project is to optimize the manufacturing of blade-integrated disks made from a nickel-based superalloy by using the Process Signature as a correlation between internal material load and material modification.
Especially for the determination of internal material loads, a numerical chip formation model was qualified. An extensive experimental test program with lowest possible workpiece material consumption was designed and used to determine the Process Signature. On this basis, an optimized two cut strategy is developed for a maximum material removal rate while taking into account limits for modifications in terms of residual stress, roughness and the existence of white layers.
Cooperation: Rolls-Royce Deutschland
Funding: DFG (SFB/TRR 136, Transferprojekt)
Contact:
Dr.-Ing. Jens Sölter
Tel.: +49 421 218 51187
E-Mail: soelter@iwt.uni-bremen.de
The overall objective of the transfer project is to develop technological solutions for increasing the productivity in industrially used geometrically defined hard machining of steels with special consideration of the workpiece surface layer and tool wear.
For this purpose, based on experimental and simulative analyses, a Process Signature and the further correlations of the causal sequence for external longitudinal turning of hardened workpieces are to be developed.
Cooperation: Leibniz-IWT FT/WT, Thyssenkrupp Rothe Erde
Funding: DFG (SFB/TRR 136 Transferprojekt)
Contact:
Dr.-Ing. Jens Sölter
Tel.: +49 421 218 51187
E-Mail: soelter@iwt.uni-bremen.de
The overall aim of the AMELA project is to investigate metastable β-titanium alloys for the additive manufacturing of aerospace components. These alloys can be processed with low residual stress and high ductility by laser powder bed fusion (LPBF) and the mechanical properties can be adjusted by a subsequent heat treatment (α-aging).
The microstructural changes are investigated along the process chain covering the LPBF-process, heat treatment, hot isostatic pressing and surface machining (milling) and correlated with the effects on the mechanical properties and the machinability of the material. It could be shown that the machinability (tool wear, cutting force, roughness, chip form) in the metastable β-microstructure is advantageous compared to the aged and also conventionally rolled variant.
Cooperation: Leibniz-IWT FT/WT, TU Chemnitz
Funding: BMWK LuFo VI-2 20E1901B
Contact:
Dr.-Ing. Jens Sölter
Tel.: +49 421 218 51187
E-Mail: soelter@iwt.uni-bremen.de
In order to develop an improved understanding of the wear formation of coated carbide tools, a (whitebox) model based on chip formation simulations is combined with an artificial neural network (blackbox model) to form a greybox model.
The whitebox model enables an approximate determination of current tool wear parameters based on the measured thermo-mechanical loads. Together with in-process measurement, these are incorporated into the blackbox model to precisely predict tool wear.
Cooperation: BIMAQ
Funding: DFG (SPP 2402)
Contact:
Dr.-Ing. Lars Langenhorst
Tel.: +49 421 218 51113
E-Mail: langenhorst@iwt-bremen.de
This transfer project focuses on investigating how material strain rates influence process design through process signature components, in collaboration with an industry partner.
By concentrating on machine hammer peening, the aim is to understand how high strain rates affect material modification. We specifically study the effects of impact energy and tool diameter on the peening process through experimental tests and finite element simulations. A finite element model has been developed to quantify these effects, providing valuable insights into the optimization of machine hammer peening processes.
Kooperation: Ecoroll AG Werkzeugtechnik
Förderung: DFG (SFB/TRR 136 Transferprojekt)
Kontakt:
M.Sc. Zhaoyu Chen
Tel.: +49 421 218 51148
E-Mail:chen@iwt-bremen.de
The production of components on Mars poses a particular challenge for its colonization and the processes and procedures used there. Components have to be manufactured with very limited resources using raw materials that are only available to a limited extent on Mars.
The aim of the project is to investigate the manufacturability of “enough to use” components made of metals with a varied proportion of regolith-analogue material. Dry deep rolling is used as a process to mechanically consolidate and to smoothen the surfaces of the pre-sintered components so that they can be handled in an energetically optimized manner using dry adhesive methods. The process chain of sintering, deep rolling and handling considered in the project has been realized with raw material containing up to 30 % regolith, and the positive effects of deep rolling have been quantified.
Cooperation: Leibniz-IWT FT/VT, BIME
Funding: Universität Bremen
Contact:
Dr.-Ing. Jens Sölter
Tel.: +49 421 218 51187
E-Mail: soelter@iwt.uni-bremen.de
The Department of Manufacturing Engineering of Leibniz-IWT is involved in the further development of the cold spray technology as a repair method for manufacturing defects in aircraft production and damage repair during maintenance in the main work package 5 (HAP5) “Repair, Reuse, Material Recycling”. The aim is to ensure adequate restoration of the original material properties in aluminum structures.
Cooperation: Leibniz-IWT FT/WT, Airbus
Funding: BMWK LuFo 6.2
Contact:
Dr.-Ing. Rüdiger Rentsch
Tel.: +49 421 218 51191
E-Mail: rentsch@iwt.uni-bremen.de
This subproject focuses on the development of environmental friendly aviation technology by significantly reducing CO2 and NO emissions based on new propulsion technologies using hydrogen and lightweight construction.
Additive manufacturing processes such as Laser-powder-bed-fusion (LPBF) and cold spray (CS) of titanium alloys with high specific strength are key technologies for achieving the project goals.
Cooperation: Leibniz-IWT FT/WT, TU Chemnitz
Funding: BMWK LuFo 6.3
Contact:
Dr.-Ing. Rüdiger Rentsch
Tel.: +49 421 218 51191
E-Mail: rentsch@iwt.uni-bremen.de
The main objective of the research proposal is to fundamentally describe the heat partition to the workpiece for industry relevant dry cutting processes.
During the first project phase heat partitioning models have been successfully developed and validated for quasi orthogonal cutting and for surface milling. The resulting heat partitioning diagram provides the fraction of heat generated in the primary shear zone dissipating into the workpiece as a function of two dimensionless parameters. In the second project phase the applicability of the approach to external turning was investigated. A process-independent functional relationship for heat partitioning in metal cutting processes was established.
Funding: DFG
Kontakt:
Dr.-Ing. Jens Sölter
Tel.: +49 421 218 51187
E-Mail: soelter@iwt.uni-bremen.de