The Chair of Manufacturing Engineering conducts extensive research in the fields of additive manufacturing and assembly technology. Both industry-oriented projects and fundamental research form the basis of our scientific work.

Additive manufacturing using powder bed processes is increasingly developing into a key technology for the industrial production of complex and customized components. Particularly in industries such as mechanical engineering, medical technology and aerospace, the requirements for process reliability and component quality are continuously increasing. However, fluctuations in powder bed temperature can lead to defects, porosity or inadequate mechanical properties. There is therefore a strong need for precise monitoring solutions for the in-situ monitoring of powder bed temperature during the manufacturing process.

The ColorTEMP-PBF project focuses on the development of powder mixtures consisting of PA12 powder and color-sensitive pigments that make temperature changes within the powder bed visible. In addition, a camera-based monitoring system with AI-supported data analysis is being developed to analyze powder bed temperature during the PBF-LB/P process. To this end, suitable pigments are selected, material mixtures are characterized and datasets are generated for training the artificial intelligence. The objective of the project is to develop a functional prototype capable of detecting process anomalies at an early stage and improving process quality in additive manufacturing.

September 2023 – August 2026

The objective of the project is to develop standardized manufacturing, testing and evaluation methods (tensile and bending tests) for additively manufactured hollow-structure test specimens made of plastics. The focus is on MEX processes (Material Extrusion, analogous to FDM). The developments will enable the anisotropic strength properties of additively manufactured hollow structures to be determined reproducibly and reliably for the first time. This will provide robust mechanical characteristic values for structural design and simulation, representing an important step towards the reliable and safe use of additively manufactured functional components with hollow structures.

The objectives of the work carried out by the Chair of Manufacturing Engineering are the development of new additively manufactured test specimens and the development of an inline quality control system for test specimen production.

July 2022 – June 2025

The 3D Battery project investigates the approach of additive manufacturing (also known as 3D printing) for the production of lithium-ion batteries (LIBs) with three-dimensional architectures. This approach enables the available cell volume to be utilized efficiently and allows for the production of thinner (< 1 mm) and shape-flexible batteries. Adapting the battery design to the specific requirements of the end device facilitates integration.

A key aspect of the project is the demonstration of the additive manufacturing of a complete microbattery, including the electrodes and housing, in a single manufacturing process. This requires the development of customized printing inks for the electrodes, as well as the adaptation of printing processes for the precise dispensing of electrode dispersions and the material extrusion of the battery housing.

The project aims not only to revolutionize the manufacturing of microbatteries but also to provide important insights into scaling additive manufacturing to larger batteries for use in automotive and stationary applications.

Companies manufacturing batteries or their components, as well as manufacturers of additive manufacturing equipment, are expected to benefit from the results and gain essential information for adapting their technologies.

January 2023 – March 2025

The application of a novel material for Laser Powder Bed Fusion is the focus of this research project. The glass-forming titanium-based alloy containing sulfur promises excellent component properties due to its high corrosion and wear resistance; however, it cannot currently be processed into functional components using conventional manufacturing methods. To unlock this potential, the Laser Powder Bed Fusion process is being investigated as a promising processing route. The focus is on investigating the influence of the process on the material and the resulting component properties. The amorphous structure is crucial in this context and the analysis of laser–material interaction is an essential part of this project.

October 2022 – September 2025

Stent grafts are used in the treatment of aortic aneurysms, i.e. enlargements of the main artery. These devices are stabilizing vascular prostheses that typically consist of a textile polymer graft into which a metallic wire mesh is sewn. The implantation of these stent grafts is performed using X-ray imaging, which involves radiation exposure for both medical personnel and patients.

The MEVAR joint research project aims to manufacture stent grafts from a polymer that is visible under MRI, thereby reducing radiation exposure, while also automating the currently very costly and largely manual manufacturing process using polymer 3D printing. To this end, a high-temperature material extrusion system is being developed that enables the printing of tubular components from biocompatible high-performance polymers specifically developed for this process.

March 2021 – August 2023

The aim of the MatEX-MEX project is to develop a modular exhaust air purification system for 3D printers using Material Extrusion (MEX). The focus is on filtering material-dependent emissions, including volatile organic compounds (VOCs) and ultrafine particles, in order to enable a stable, reproducible and environmentally and health-conscious printing process. The system is designed to be adaptable to various desktop 3D printers while achieving an emission reduction of up to 99%.

Various filament materials and their emission characteristics are systematically investigated as part of the project. The objective is to maintain print quality through adapted process parameters while significantly reducing the impact on people and the environment.

In particular, the project aims to make the use of 3D printers in non-industrial environments such as offices, educational institutions and private households safer.

February 2020 – January 2023

In this project, the University of Duisburg-Essen is investigating the entire horizontal process chain of laser sintering. Various aspects of the process, post-processing and powder handling are taken into account. The main objective is to develop quality assurance measures for the material system and the process. Providing consistent powder quality by eliminating the prevailing quality fluctuations forms the basis for series production of reproducible, high-quality products with the highest possible resource efficiency.

For the design of extrusion dies for polymer melts, established geometries such as spiral mandrels for blown film extrusion have been used for many years. The design of these geometries, particularly in the case of complex variants, is also subject to manufacturing-related constraints. In addition to thermal management, near-wall flows are particularly challenging. These are established immediately after entering the spiral and therefore have a significant influence on the residence time distribution within the die. With today's additive manufacturing technologies, there is significant potential for the thermo-rheological optimization of melt-carrying channels, thereby improving the economic efficiency and sustainability of extrusion processes. The increased geometric freedom compared with conventional manufacturing processes allows the design of structures and channel paths that positively influence flow behavior and consequently improve die performance. From a manufacturing perspective, the achievable surface quality in additive manufacturing processes represents a major challenge.

Building on the first project phase, this DFG-funded project develops a methodology for CFD-based die design while simultaneously taking into account the constraints of additive manufacturing processes, such as overhang angles, resolution, surface roughness and others. Furthermore, the additive manufacturing process is optimized for the production of such geometries and post-processing methods suitable for machining complex internal structures with geometrically undefined cutting edges are analyzed. These methods include abrasive flow machining, electroplating and plasma polishing.

Bulk metallic glasses (BMGs) feature extraordinary mechanical properties such as high strength and elasticity. However, manufacturing of BMGs remains challenging, since rapid quenching is required to vitrify metallic melts. Laser powder bed fusion (PBF-LB/M) evolved as a suitable processing strategy to enable the fabrication of large and complex BMGs, yet it leads to embrittlement. The aim of this project is to evaluate the possibilities in manufacuturing BMG lattices via PBF-LB/M to overcome this issue. Therefore, the technological implications such as thermal history, surface roughness and size effects within BMG lattice structures will be investigated. The project is funded within the UDE Post doc Seed funding. The Programme aims to promote Excellent Early Career Researchers and to lead outstanding postdoctoral researchers of the University of Duisburg-Essen to a third-party funding proposal.

November 2021 – December 2023

Customized production, also known as lot size one, is particularly relevant where technical requirements meet economically viable manufacturing. In the field of competitive and recreational canoeing, however, there are currently no economically viable solutions despite the need for individual customization. In this project, the Chair of Manufacturing Engineering at the University of Duisburg-Essen aims to develop, implement and evaluate a fully digital process chain for the production of customized seat shells.

To enable broad application, the scope will not be limited to canoes but will also be extended to other use cases, such as racing seats and wheelchair seat inserts. Specifically, the open freeform surface of the seat impression is to be digitized appropriately, adapted to individual requirements and subsequently transferred to the automation components in an already optimized form. The development of suitable interfaces and standards, including standards for process-related parameters, represents the key challenge for a fully digital process chain and thus for economically viable lot-size-one production.

March 2018 – March 2020

Additive manufacturing enables the time- and resource-efficient production of components with virtually unlimited design freedom. Particularly in the aerospace and medical technology sectors, additive Laser Powder Bed Fusion offers significant innovation and application potential. Despite the continuous development of the process, there is currently a considerable need for improvement in quality management and process stability. Incorrectly configured process parameters or fluctuations in process boundary conditions can impair the resulting mechanical and technological component properties or lead to process failure.

Disadvantages of existing methods for process monitoring and control include the large volumes of data generated and the lack of specific material parameters required for process control. The use of a simple, non-contact optical inspection technology is therefore advantageous and is provided by Laser Speckle Photometry (LSP), developed at Fraunhofer IKTS. This method uses a camera to detect temporal changes in the characteristic interference patterns generated when a surface is illuminated with coherent light and evaluates them using specialized algorithms. This evaluation can provide information, for example, about existing component defects or changes in the stress state.

The results generated in this project provide manufacturers and users of Laser Powder Bed Fusion technology—predominantly SMEs in Germany—with a scientifically sound basis for monitoring additive Laser Powder Bed Fusion processes using LSP. The objective is to transfer the fundamental relationships underlying the LSP method to the additive Laser Powder Bed Fusion process. To this end, suitable concepts for the hardware integration of the measurement system and the software-based evaluation of the measurement data will be developed, implemented and tested in a laboratory demonstrator measurement system.

January 2018 – December 2019

Due to their amorphous microstructure, metallic glasses possess unique mechanical properties in terms of strength and elasticity, making them highly attractive for highly stressed components. To date, the component dimensions achievable through conventional manufacturing processes, such as casting, have been limited to just a few centimeters. Due to its very high cooling rates, which are largely independent of the cross-sectional area, Laser Powder Bed Fusion has the potential to significantly increase the achievable size and complexity of components.

The objective of the project is to enable the outstanding material properties of metallic glasses for broader industrial applications. In this context, the influence of process-related parameters on solidification morphology and the resulting mechanical properties will be investigated and compared with conventional manufacturing routes. Furthermore, application-oriented demonstrator geometries will be manufactured to combine the advantages of additive manufacturing with the outstanding mechanical properties of metallic glasses and to demonstrate the resulting technological benefits. This will be achieved through process and alloy optimization based on Zr- and Cu-based alloys.

July 2017 – July 2019

Since the commercialization of additive manufacturing technologies, their fields of application have expanded significantly across a wide range of industries. Their use is increasingly shifting from pure prototyping toward the production of small series, as tool-free, layer-by-layer manufacturing offers substantially greater geometric and design freedom than conventional processes without necessarily increasing energy demand or production costs. The research results enable the participating industry partners to design laser-sintered components specifically for series applications under long-term mechanical loading, such as static or dynamic tensile loads and to tailor their service life through suitable post-processing steps.

For conventional manufacturing processes such as injection molding, various post-processing methods are already established for modifying color appearance, gloss and surface roughness. However, only a limited number of approaches are currently available for deliberately adjusting process-inherent characteristics of laser-sintered components, such as roughness and surface condition. This project therefore investigates post-processing methods specifically adapted to polyamide 12 with the aim of reducing surface roughness.

October 2016 – September 2018

Sandwich sheet structures offer significant potential for lightweight applications through the efficient use of materials, their geometric design and the possibility of integrating additional functions. However, manufacturing these structures using either forming processes alone or purely additive methods involves considerable disadvantages, such as poor material utilization or long production times.

One approach to overcoming these limitations is to combine the additive manufacturing of metallic sandwich sheets in a powder bed with subsequent forming operations. The combination of these processes, developed and fundamentally investigated within this research project, represents a novel technological approach and enables the production of highly complex structures with tailored core geometries and integrated functions.

The aim of the project is therefore to design sandwich sheet structures through numerical and experimental methods and to investigate their formability. To further increase component functionality, additively manufactured sandwich sheets with locally varying thicknesses are developed, produced and tested in forming experiments.

Load-adapted core structures with graded dimensions, local reinforcements or integrated functional elements provide additional potential for improving lightweight performance.

November 2013 – April 2016

In recent years, additive manufacturing technologies and the components produced using these processes have become increasingly important across a wide range of applications. The growing technological maturity of these processes has led to a transition from pure prototyping toward the production of pre-series components and, increasingly, series components through rapid manufacturing.

The transition to series production or small-series production imposes significantly more stringent requirements on both the components and the manufacturing process than is the case for prototypes. In particular, series-produced components must meet all relevant requirements under operating conditions throughout their intended service life. This requires a fundamental understanding of the long-term properties of the manufactured components and the materials used to produce them. To date, however, knowledge in this area remains limited.

The research project “Resource-Efficient Small-Series Production by Polymer Laser Sintering – Stabilization of the Long-Term Properties of Laser-Sintered Components” therefore aims to establish a fundamental understanding of these relationships. Using a holistic approach, the long-term behavior of components produced from various commercially available laser-sintering materials is investigated.

Different material modifications, process settings and manufacturing systems are considered as influencing factors in order to derive findings on long-term component properties that are as broadly applicable as possible.

September 2012 – August 2014

During the melting and cooling of metal powder in the laser beam melting process, cooling rates of up to 3.5 × 10⁶ K/s can occur. As a result, high residual stresses (thermal stresses) develop within the solidified components. These stresses are caused by locally non-uniform elastic and plastic deformations that become effective during cooling without the application of external loads. This quality-related issue can lead to process failure during manufacturing or, subsequently, to component failure during service.

The objective of this research project is to develop a scientifically and technically sound concept for reducing residual stresses in components produced by laser beam melting. Simulation-based and experimental investigations are conducted to identify optimized material, process and exposure parameters. These measures are intended to increase process reliability in laser beam melting and thereby enable more efficient component production.

To achieve this, key process variables are investigated and further developed with regard to their influence on residual stress formation and reduction. These include the exposure strategy (laser scan path used to melt the powder layer), support structures (design and geometry of the supporting structures), the powder layer (layer thickness and powder properties) and radiative heating (preheating of the powder layer).

April 2012 – April 2014

Within the AiF project “Knowledge-Based Support System for 3D CAD/CAM Processes Suitable for Rapid Prototyping” (IGF 15351 BG), the participating research institutions contributed to improving the availability of practical, application-ready knowledge for both experienced users and newcomers to Additive Manufacturing. The processes initially investigated included laser sintering, laser beam melting, 3D printing, multi-jet modeling and stereolithography.

One focus of the project was the determination of manufacturing-oriented component orientation while taking both qualitative and economic constraints into account. Concepts were successfully developed for integrating the various influencing factors into optimization strategies tailored to specific application scenarios.

Another focus was the development of process-specific design guidelines and initial rules for the production of functional components. In addition, general topics such as the influence of STL data on component quality were investigated and corresponding recommendations for users were derived.

The results of the project demonstrated considerable potential for further research. Consequently, the corresponding follow-up project (IGF 424 ZBG) was conducted from 2012 to 2014 with the objective of supporting users throughout the entire process chain, from component design to the finished product. To achieve this, solutions were developed for the qualification of product model data and for the automation and optimization of key preprocessing steps, while incorporating additional aspects and capabilities that had not previously been considered.

February 2012 – April 2014

Compared with conventionally manufactured components, both laser-sintered and laser-beam-melted components exhibit relatively rough surfaces due to their layer-by-layer production from powder-based feedstock. Although surface roughness can be reduced through adapted process control and optimized scanning strategies, it cannot be completely eliminated. Surface finishing technologies therefore provide an important means of extending the range of potential applications.

One focus of the AiF-ZIM project was the optimization of the manufacturing processes through the qualification of Inconel 625 for laser beam melting and polypropylene for laser sintering. In the subsequent course of the project, the process chain was extended to include selected post-processing methods with the aim of investigating their potential for improving component quality.

To evaluate geometric product specifications, particularly dimensional and form accuracy as well as surface quality, test specimen geometries tailored to the respective manufacturing processes were developed. Particular emphasis was placed on the qualification of blasting and mass finishing processes. The investigations included identifying the main influencing factors for defined target characteristics, determining optimized process parameters and defining process-specific limitations and capabilities.

The objective was to establish a systematic comparison between the conventional process chain and the newly developed process chain incorporating post-processing operations. In addition, the extended process chain was evaluated with regard to its suitability for industrial applications.

April 2011 – July 2013

Additive laser beam melting is considered to offer significant potential, particularly in the aerospace industry, toolmaking, medical technology and the production of customized small-series components. However, the application of this technology is currently still limited to a relatively small number of niche applications. In addition to economic considerations, this is largely due to the still insufficient capabilities for process monitoring and quality control of the manufactured components.

Against this background, the objective of the AiF-IGF project 17042 N was to develop a high-resolution imaging system for monitoring additive laser beam melting processes, thereby contributing to the quality management of laser-beam-melted components. Taking advantage of the layer-by-layer manufacturing principle, the approach was to acquire high-resolution images of both the powder layer and the resulting exposure pattern for every layer of the build process. These images provide the data required for image-based defect detection.

The research project was successfully completed in 2013. The work is intended to be continued in a subsequent research project.

February 2011 – January 2013

Rapid manufacturing technologies for small-series production, such as polymer laser sintering, are becoming increasingly important. The research was motivated by the lack of reliable information regarding process stability and reproducibility, as well as the limited ability to guarantee specific component properties.

Within the project, a quality assurance system covering the entire rapid manufacturing process chain of laser sintering was developed. The system enables the individual steps of the process chain to be systematically controlled and provides reliable information on material, process and component quality.

The work was based on a fundamental investigation of process interactions, with particular emphasis on analyzing the melt temperature profiles occurring during the laser sintering process using high-speed thermography. The results obtained made it possible to explain numerous mechanisms and interactions within the process. These findings were consolidated into a “Theory on the Continuation of Melting Processes in Laser Sintering.”

Based on these findings, various measures were derived to ensure material quality, optimize process parameters, establish a process that is robust against disturbances and improve the manufacturing equipment. The implementation of these measures increases achievable component quality and, in particular, improves the reproducibility of component properties.

June 2010 – May 2012

The objective of the AiF-ZIM project “Evaluation System for Products Manufactured Using Rapid Prototyping Technologies and Subsequent Processes” (KF2095009US9) was to develop criteria for quality assessment, apply them to selected manufacturing processes and demonstrate the reproducibility of relevant properties for both test specimens and components representative of series production.

The basis of this collaborative research project was the identification and systematic classification of the requirements for additively manufactured components and investment-cast parts. These requirements were represented by means of a representative test specimen geometry. Defined measurement and testing methods were used to determine the relevant assessment criteria, while the introduction of a system of key performance indicators enabled a generally applicable evaluation of component quality.

As part of the investigations, the test specimen geometry and the associated indicator system for evaluating additive manufacturing processes were initially qualified for laser sintering and its subsequent processes. By deliberately introducing disturbances into the process, the key process parameters and their influence on the defined requirement profiles were identified, enabling component reproducibility to be assessed and ensured.

In subsequent stages, the investigations were extended to additional additive manufacturing technologies, including stereolithography, laser beam melting, multi-jet modeling, fused deposition modeling and 3D printing. By developing process-specific testing procedures, a systematic framework for evaluating the quality of additively manufactured components and manufacturing processes was ultimately established.

April 2009 – March 2011

A manufacturing approach was developed to enable the cost- and time-efficient production of components with highly complex 3D geometries made from difficult-to-machine nickel-chromium alloys, such as Hastelloy X and Inconel.

Instead of relying exclusively on conventional high-speed cutting (HSC) for manufacturing components from difficult-to-machine Ni-Cr alloys, a suitable process chain combining Direct Metal Laser Sintering (DMLS) and HSC was developed, optimized and evaluated with regard to its overall process consistency. The investigations were carried out using burner blades and similar components as representative applications.

Through the close cooperation between the two research institutions, the project objectives were successfully achieved in all relevant areas. A comparison of the detailed project results with the originally defined work packages confirmed that no substantive changes to the project plan were required during the project period.