Ludger Overmeyer

Leibniz Universität Hannover

The MaterialDigital initiative represents a major driver toward the digitalization of material science. Next to providing a prototypical infrastructure required for building a shared data space and working on semantic interoperability of data, a core focus area of the Platform MaterialDigital (PMD) is the utilization of workflows to encapsulate dat...

Magnesium alloys pose challenges in additive manufacturing, due to the difference between the melting temperature of magnesium oxide (2825 °C) on the powder particles and the boiling point of metallic magnesium (1093 °C). A promising approach to overcoming the difficulties is the reduction of the thickness of the high‐melting oxide layer on the sur...

The extrusion process is one of the most important methods for continuous processing of rubber compounds. An extruder is used to give the rubber compound a geometrically defined shape as an extrudate. To ensure that product‐specific requirements are fulfilled, the extrusion process and the resulting extrudate are currently monitored using various s...

Understanding the effects of gravity on manufacturing processes is a pioneering extension of the process parameter space used to date. Until now, the improvement of manufacturing technologies has mainly focused on process parameters such as temperature, pressure, and material composition, as access to variable gravity environments is limited. The E...

3D printing is one of the key technologies in space exploration. The disparity in gravitational forces between Earth and space presents both challenges and opportunities with regard to material handling. This paper examines the potential of employing ultrasonic levitation as a handling tool for substrate-free additive manufacturing processes in mic...

In rubber extrusion, precise temperature control is critical due to the process’s sensitivity to fluctuating parameters like compound behavior and batch-specific material variations. Rapid adjustments to temperature deviations are essential to ensure stable throughput and extrudate surface integrity. Based on our previous research, which initiated...

Electro-optical circuit boards (EOCB) offer great potential for short-ranged data transmission in highly electro-magnetic inflicted environments. Finding a cost-efficient way to manufacture EOCB only using additive printing processes could establish, increase, and secure data transmission in PCB systems. Flexo printing is an efficient manufacturing...

A continuously growing number of product variants increases the demands on the flexibility of intralogistics transportation. One way to achieve greater flexibility is the use of cellular automated guided vehicles, which can be variably interconnected depending on the size of the product to be transported. This article explains the characteristics o...

Rubber mixing is a complex manufacturing process that poses challenges for process control due to the high number of control variables including mixing parameter settings, rheological behaviour, compound viscosity and batch-dependent material variations. Already small deviations from the control variables can influence the compound properties, lead...

Tools for implementing a systematic quality management are necessary for the use of material extrusion as an additive manufacturing process for products with high quality requirements. Well-defined quality classes are crucial for ensuring that the requirements for a product can be communicated transparently and that the existing properties can be e...

Glass is an ideal material for optical applications, even though only a few micromachining technologies for material ablation are available. These microstructuring methods are limited regarding precision and freedom of design. A micromachining process for glass is laser induced deep etching (LIDE). Without generating micro-cracks, introducing stres...

Hybrid components, made of multiple materials, can meet the increasing demands for lightweight construction and functional integration in the automotive and aircraft industry. Hybrid semi-finished components are produced by applying a high-alloy cladding to a low-alloy base material before hot-forming and machining the workpiece. Throughout this pr...

Rubber extrusion processes involve a high number of control parameters and batch-dependent material fluctuations, leading to lengthy and error-prone testing cycles for new products. To address this challenge and enable a more sustainable production, an artificial neural network-based data mining algorithm is developed that identifies correlations b...

In order to develop hardware that can be used in space, tests under those space conditions are often important to ensure the functionality in advance. Facilities that are used to recreate gravity conditions of space include space stations, satellites, parabolic flights and earthbound facilities. Drop towers are earthbound facilities, that can repli...

In this study, the application of the ABA cladding strategy in coaxial wire-based cladding processes is investigated. Individual weld seams (A) are first welded on the substrate and additional weld seams (B) are deposited into the intermediate spaces in the second step. Thereby, two different seam geometries are present in the cladding. Unidirectio...

In early innovation phases, the monetary evaluation of process innovations is a challenge for companies due to a lack of data. However, an innovation evaluation is essential in an early innovation phase to ensure that process innovations deliver economic value added (EVA) in early innovation phases and to channel technology transfer expenditures in...

This paper is about the challenges in developing the Laser Metal Deposition process with metal powder for use in microgravity. The modified gravitational conditions are set up for a few seconds using a drop tower, the Einstein-Elevator of the Leibniz University Hannover. In addition to the drop tower, the specially adapted setup of the experiment w...

The additive manufacturing (AM) of elastomeric parts based on high-viscosity reinforced rubbers has increasingly become a topic of scientific research in recent years. In addition to the viscosity, which is several decades higher during processing than the viscosities of thermoplastics, the flowability of the compound after the printing process and...

Microgravity platforms enable cold atom research beyond experiments in typical laboratories by removing restrictions due to the gravitational acceleration or compensation techniques. While research in space allows for undisturbed experimentation, technological readiness, availability and accessibility present challenges for experimental operation....

The Collaborative Research Center 1153 is investigating an innovative process chain for the production of hybrid components. The hybrid workpieces are first joined and then formed by cross-wedge rolling. Pinion shafts were manufactured to investigate the behavior of the joining zone under increased complexity of the forming process. For this purpos...

In contrast to conventional components made from a single material, hybrid multi-material components allow the production of load-adapted parts with different materials in different structural and functional areas. Hardenable and forgeable steels with a high carbon content are suitable for increasing fatigue and wear resistance and thus an extensio...

We present an all-optical focused ultrasound transducer with a sub-millimeter aperture and demonstrate its capability for high-resolution imaging of tissue ex vivo. The transducer is composed of a wideband silicon photonics ultrasound detector and a miniature acoustic lens coated with a thin optically absorbing metallic layer used to produce laser-...

Development of space proven technologies, fundamental research in microgravity and preparation of future space missions all benefit from next generation drop tower facilities like the Einstein-Elevator. The facility is being made available within a DFG core facility center in Hannover.

For rubber extrusion, ITA is developing an artificial intelligence (AI)-based process control system that responds to batch-dependent variations. The goal is to reduce scrap and sustainably increase process stability.

We demonstrate and discuss the integration of Bragg gratings in aerosol-jetted polymer optical waveguides, produced in the optical assembly and connection technology for component-integrated bus systems (OPTAVER) process. By using a femtosecond laser and adaptive beam shaping, an elliptical focal voxel generates different types of single pulse modi...

Zusammenfassung Die optische Absolutdrehwinkelmessung ermöglicht die kontaktlose und referenzfreie Messung von Winkelpositionen an rotierenden Wellen, ohne dass zusätzliche Aufbauten oder Verkabelungen an dieser angebracht werden müssen. Neben den klassischen Methoden zur Steigerung der Robustheit und Effizienz des Messverfahrens durch optimierte H...

The selective laser sintering (SLS) process is very temperature sensitive, so slight temperature changes can lead do inhomogeneous prints with varying mechanical properties. The laser power is kept at a fixed value while printing because most SLS printers assume a constant temperature in the building volume on the powder surface. The assumption of...

Additive manufacturing enables the economical production of complex components with a high degree of customization. Therefore, the medical industry is using the advantages of additive manufacturing to produce individualized medical devices. Medical devices are subject to special quality control requirements that additive manufacturing processes do...

The applications of the additive manufacturing process Laser Metal Deposition include the production of near-net-shape parts, coating, joining, feature addition and, above all, repairs. This potential makes the technology interesting not only for applications on earth, but also for use in space. In the case of future space missions to Mars and beyo...

The integration of the knowledge of different engineering disciplines to build a three-dimensional optical short-range interconnect system is the core of this book. For this purpose, the physical and technological principles of optical technologies have to be considered. The focus here is on optical transmission technology. Attenuation, the propaga...

The local wetting control of film substrates using flexographic printing is investigated in order to enable the additive manufacturing of optical waveguides in a subsequent process step. Process-specific advantages are exploited in order to achieve increased performance of the optical structures. By conditioning film substrates, the achievable aspe...

This article presents the design potential of a novel additive manufacturing process for three-dimensional (3D) multilayer devices with vertical interconnect accesses (VIA). The technical approach is based on multilayer printing of alternating metal-containing and insulating ink layers on 3D component surfaces. Additional laser ablation of the insu...

Additive manufacturing is an established technique in much of industry for manufacturing complex structures from polymer and metal materials. The additive manufacturing of glass materials is a very young process, which is based on through various approaches. For example, such processes are based on a glass powder bed or the layer-by-layer depositio...

One of the main challenges in miniaturizing optoacoustic technology is the low sensitivity of sub-millimeter piezoelectric ultrasound transducers, which is often insufficient for detecting weak optoacoustic signals. Optical detectors of ultrasound can achieve significantly higher sensitivities than their piezoelectric counterparts for a given sensi...

Additive manufacturing of thermoplastics and metals is a sustainable and established process in industry for the rapid production of individual technical components. For a long time, this technology was not accessible for the group of elastomers, or only to a limited extent in the form of thermoplastic elastomers or silicone rubbers. The developmen...

Nowadays, there is a strong and growing ambition to switch from combustion technology to battery-electric drives, and energy storage is spotlighted. Laser beam welding is an appropriate and favorable welding technology in battery production. Due to the high welding speed, the local heat input, the contact freeness efficient, and automatable process...

In order to use laser transmission welding (LTW) for additively manufactured parts such as prototypes, small series, or one-off products, an enhanced process knowledge is needed to overcome the difficulties in the part composition resulting from the additive manufacturing process itself. In comparison to an injection molding process for thermoplast...

With an estimated amount of about 1.6 metric million tons, unexploded ordnances (UXO) in the German North and Baltic Sea pose a serious threat to the environment due to increasing corrosion. One way to allow safe salvage of the objects from the sea is to weaken them and then disarm them by low order detonation. This paper deals with the weakening b...

With increasing demand for pure copper welds in the production of electronic connections, various approaches were pursued to reduce the challenging spatter and melt ejection susceptibility of laser beam welding processes in copper materials. One is the use of adjustable intensity profiles of infrared laser beam sources with a combination of a core...

There are several ways to create optical filters on glass, such as the low-cost sol-gel coating. However, to make this process even more effective and flexible, a laser instead of a conventional furnace process was used to anneal the borosilicate glass samples. In previous studies, it was demonstrated that it is possible to generate similar refract...

The bearing steel 100Cr6 is of great interest for cladding applications that are subject to tribological stresses, since it has high hardness of up to 62 HRC. However, the material is considered not weldable due to its high carbon content. In this study, a process for laser metal deposition welding with the wire material 100Cr6 is developed. For th...

For applications of the chemical, gas and oil industry duplex stainless steels are mostly used due to good corrosion resistance and mechanical properties. These performances are archived by a microstructure of ferrite and at least of 30 % austenite. To ensure the properties, the energy per unit length EL of the welding process must be suitable adju...

Laser cutting of carbon fibre reinforced plastics (CFRP) has shown promising potential as an alternative to conventional manufacturing processes. Laser cutting has major benefits of contactless and therefore wear-free machining and high automation potential. The main challenge is to reduce the heat input into the material during the process. Excess...

Due to its thermal and chemical resistance, borosilicate glass finds a wide range of applications in optics, chemical laboratories and in glass apparatus engineering. For the manufacturing of complex glass components, the welding of semi-finished glass products is essential. In the majority of industry, this is realized by operating gas burners in...

As powder bed based additive manufacturing (AM) is gaining more traction in the research and industry, significant efforts are made to expand the capability of AM in combining different materials. Conventionally, multiple materials, sealants and processes are necessary in order to join metal and glasses in assemblies. The development of a single-st...

Laser transmission welding (LTW) is a known technique to join conventionally produced thermoplastic parts, e.g. injected molded parts. When using LTW for additively manufactured parts (usually prototypes, small series), this technique has to be evolved to overcome the difficulties in the part composition resulted in the additive manufacturing proce...

Aluminium alloys, like AlMgSi1 and AlMg3, cannot be joined in industrial processes by laser beam brazing without the use of fluxes due to their resistant oxide layer. The aim of this study is to dispense with the use of flux. For the investigations, an oxygen-free atmosphere was created by using the highly reactive gas monosilane and thus achieving...

In this paper, objective functions for the optimisation of modular conveyor systems will be introduced. Modular conveyor systems consist of conventional as well as modular conveyor hardware, which are arranged in form of matrix-like layouts. The aim of an ongoing research project is to provide small and medium-sized enterprises with a user-friendly...

Limited visibility during the operation of forklifts is one of the most significant sources of danger in in-plant material handling. Existing systems record concealed areas via cameras and display them directly on monitors in the driver's cab. Augmented reality (AR) allows to display information directly in the driver's field of view (FoV). Conceal...

Claddings are used to protect areas of components that are exposed to particular chemical, physical or tribological stresses. The aim when developing a cladding process is to achieve a cladding with low waviness in order to reduce the amount of machining required. Computational models and FEA simulations can be used to determine process parameters...

Deposition welding of components using the laser metal deposition (LMD) process is a proven method of creating 3D structures. It is used for the manufacturing of components, the repair of machine parts and for cladding. Up to now, claddings have mainly been investigated in the flat welding position. Some investigations on deposition welding in vert...

Laser melting experiments were carried out with the MOONRISE payload, installed on the mobile manipulator, MIRA3D. The MOONRISE payload was developed to demonstrate the feasibility of additive processing of lunar regolith with the help of lasers on the Moon within a lunar surface mission in the next years. The development of hardware for the flight...

Laser beam brazing is an established manufacturing process due to its low heat input and esthetically appealing seams. However, brazing of materials with high oxygen affinity, such as aluminum alloys, requires the removal of surface oxides prior to the brazing process, commonly through the application of chemical fluxes that may be harmful to the e...

Die bonders are faster than ever at 42,000 units per hour (UPH) these days. However, the die transfer process is often the limiting time constraint due to the inertia of the mechanical actuators. In addition, the mechanical die ejection physically limits the minimum possible die dimensions. To overcome these limitations we developed a laser-induced...

Tailored forming is used to produce hybrid components in which the materials used are locally adapted to the different types of physical, chemical and tribological requirements. In this paper, a Tailored Forming process chain for the production of a hybrid shaft with a bearing seat is investigated. The process chain consists of the manufacturing st...