Contact

Gimmler, Steffen M.Sc.
Head of permanent mold castings
Chair for comprehensive Foundry Science and Foundry Institute

Tel.: +49 (0) 241 80 - 98910
s.gimmler@gi.rwth-aachen.de

Light Metal Casting

The general demand for constant increases in performance and efficiency in all areas of industry makes it necessary, especially for the foundry sector, to develop new materials and suitable process technologies in die casting, sand casting, precision casting and permanent mold casting. The research area "Innovative Casting Processes" supports these efforts through systemic research and optimization, but also new development of casting processes. The main aspects of the research activities are fundamental material, tool and measuring technology developments which serve to produce castings and lightweight components with the highest geometric complexity and precision. Another focus is on hybrid technologies, which are characterized by novel material and process combinations (casting, sheet metal, plastics, fibers) and thus contribute to a targeted increase in the performance of structural components.

Cluster of Excellence Metal Hybrids

Cluster of Excellence "Internet of Production" (DFG)

Duration: 01.01.2019 - 01.01.2026

Research Institutions: Foundry Institute and numerous RWTH partner institutes from the fields of computer science, mechanical engineering, materials engineering, mathematics, humanities and economics.

The combined application of established manufacturing processes, design principles and materials opens up new perspectives for realizing maximum weight savings and performance enhancement as well as increasing the efficiency of production processes. Hybrid components are produced by recasting sheet metal insert structures made of steel or aluminum with Al or Mg light metal melts. The form-fit, force-fit and material-fit connections are ensured by perforations in the insert or by microscale connection forms, such as functional coatings and surface structures.

In the "Integrative Production Technology for High-Wage Countries" cluster of excellence, metal die casting is combined with plastic injection molding in a two-stage process. First, an aluminum component is produced in just one mold, to which a plastic component is injected and adhesively bonded in a second step.

Due to the necessary interaction between the individual processes of die casting and injection molding, multi-component high-pressure die casting (M-HPDC) has a large number of parameters and parameters that influence the formation of the composite. In addition to technical process development, the focus of the "Internet of Production" (IOP) cluster of excellence is on process data acquisition and evaluation, the findings of which are to be directly incorporated into process development. The networking and creation of a suitable infrastructure for data acquisition are a main focus of the current work of the GI within the framework of the subproject B1.II.

 

Ontology for Production Data

Cluster of Excellence "Internet of Production" (DFG)

Duration: 01.01.2019 - 01.01.2026

Research Institutions: Foundry Institute and numerous RWTH partner institutes from the fields of computer science, mechanical engineering, materials engineering, mathematics, humanities and economics.

In the Cluster of Excellence "Internet of Production" (IoP), the development of the digital shadow of production and the associated reference infrastructure is pursued. Here, the goal is to capture, securely transfer and subsequently process multidimensional application-specific production data sets. This serves the goal of being able to draw conclusions about the ongoing production process in real time and to intervene in it in a regulating manner if necessary. The horizontal cold chamber die casting process is one of the demonstrators in this multidisciplinary project.

It is of high importance to develop a uniform semantics in the form of an ontology for the production data, so that different scientific disciplines can speak a common language. Consequently, this is also another essential objective in the IoP.

Once all sensor and actuator signals from the die casting cell have been stored, they can be correlated with the quality of the castings using appropriate mathematical and numerical models to enable the detection and adjustment of unsuitable operating points of the system components within the die casting cell.

 

Optipor

Investigation of nucleation mechanisms of gas pores for reproducible adjustment and optimization of the porosity profile in Al-Si casting alloys to increase the resistance against fatigue damage in the range of very high load cycles (AiF)

Duration: 01.03.2020 - 28.02.2023

Research institutes: Foundry Institute, Institute of Ferrous Metallurgy

Volume deficiencies in castings such as pores or blowholes have a negative effect on the static and cyclic mechanical properties due to their locally stress-increasing, crack-like character, depending on their formation form and position. An inherent problem in the foundry industry is that there are uncertainties in the prediction of volume deficiencies, since unresolved influencing factors prevail with regard to the nucleation mechanisms. The resulting process variations and reduced manufacturing certainties lead to increased safety factors and material inputs in the design process of the components and thus to a reduction of the lightweighting efficiency.

Consequently, the aim of the project is to understand the nucleation mechanisms of gas pores and then apply them specifically to reproducibly adjust and optimize the final porosity profile in Al-Si casting alloys. In doing so, the pore pattern is to be shifted from angular and branched shrinkage pores to finely distributed round hydrogen pores, thus increasing the resistance to fatigue damage.

SFB1120 Precision determining factors

SFB1120: Component Precision through Control of Melting and Solidification in Production Engineering Processes (DFG)

Subproject B8: Investigation of precision-determining factors to minimize distortion in the permanent mold and die casting process.

Duration (2nd phase): 01.07.2018 - 30.06.2022

Research Institutions: Foundry Institute

Warpage, residual stresses and hot cracks have a decisive influence on the quality of castings. In the casting process, these quality-reducing variables develop from the solidification shrinkage of the alloy coupled with the respective local residual stresses and the geometric constraints of the mold on the component. Therefore, their reduction through appropriate component design and process control is of great interest to foundries. The development of undesirable distortion or hot cracks can in principle be counteracted at the design level before casting or during solidification by setting the necessary local cooling conditions. However, there are currently only inadequate guidelines or measures for this, as essential fundamental knowledge is not yet available.

The overriding objective of this project is therefore to develop an understanding of the fundamental relationships between distortion and hot cracking and the local cooling conditions of the molten phase by means of empirical and experimental methods. The knowledge gained will be used to derive concepts and strategies for significantly improving component quality. Possible control mechanisms will be investigated on the basis of four approaches: casting material, mold material, component design and mold design.

 

Alternative bearing metals

Alternative bearing metals for plain bearings

Development of a metallic running layer material for hydrodynamic plain bearings subjected to high mechanical and thermal loads.

Duration: 01.06.2018 to 30.11.2020.

Research institutes: GI, IWM, ACCESS

Steadily increasing mechanical and thermal loads in tribologically stressed systems are increasingly causing established white metal-based plain bearing alloys to reach their load limits. In addition, economic and ecological aspects, such as limited tin resources and toxic effects of alloying elements contained therein, raise doubts about the future viability of these alloys.

The areas of application for plain bearings can be roughly divided into heavy-duty operation and high-speed operation. As part of the AiF-funded research project, a bearing material is to be developed in cooperation with the Institute for Material Applications in Mechanical Engineering at RWTH Aachen University and ACCESS Technology GmbH, which adapts the positive properties of high-speed alloys and shifts the mechanical and thermal load capacity in the direction of heavy-duty alloys (Fig. 1).

For this purpose, the thermodynamic and kinetic properties of various alloys are modeled using the Calphad method and the Micress simulation software. Promising results are systematically investigated for their castability, as well as resulting tribological and mechanical properties.

A detailed analysis of the resulting microstructures will also contribute to the understanding and optimization of the properties. The alloys with the greatest potential will finally be centrifugally cast for the production and analysis of demonstrators.

BeSt-2

Treatment of steel sheets for die casting of low-gap and low-distortion aluminum casting/steel sheet-metal hybrids (BeSt).

Duration: 07/01/2020 - 06/30/2022.

Research facilities:

Foundry Institute, Institute of Surface Technology, Institute of Image Forming.

While in the course of the previous project a basic understanding of the form-fit and material-fit connection between steel sheet and aluminum die-cast component was developed, the direct influences of near-series process boundary conditions were not discussed in detail.

The aim of the project is to map correlations between the bond quality and the influencing variables present in the die casting process in the form of a process-dependent criterion function. This includes both the process limits of the initial and forming processes and the influences of preceding and subsequent production processes.

For this purpose, a near-series die casting tool is instrumented with real-time capable in-situ measurement technology. The measurement results obtained are used to validate criterion functions generated by casting simulation and provide a means of evaluating composite quality.