Ludger Overmeyer

Ludger Overmeyer
Laser Zentrum Hannover e.V. | LZH

Professor
Leibniz Universität Hannover

About

467
Publications
47,266
Reads
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2,663
Citations

Publications

Publications (467)
Conference Paper
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...
Preprint
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...
Article
Full-text available
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...
Article
Full-text available
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...
Article
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...
Article
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...
Article
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...
Article
Full-text available
Due to the increased integration of functions, many components have to meet high and sometimes contradictory requirements. One way to solve this problem is Tailored Forming. Here, hybrid semi-finished products are manufactured by a joining or cladding process, which are then hot-formed and finished. For the design of hybrid components for a possibl...
Article
The Tailored Forming process chain is used to manufacture hybrid components and consists of a joining process or Additive Manufacturing for various materials (e.g. deposition welding), subsequent hot forming, machining and heat treatment. In this way, components can be produced with materials adapted to the load case. For this paper, hybrid shafts...
Article
Due to a high strength-to-weight ratio, carbon fiber-reinforced plastics (CFRPs) have become a standard in the lightweight industry, which results in the development of new machining and repairing methods. Specifically, CFRP with a thermoplastic matrix material is more attractive for many applications as a thermosetting matrix material. Thermoplast...
Article
Full-text available
Qualitative uncertainties are a key challenge for the further industrialization of additive manufacturing. To solve this challenge, methods for measuring the process states and properties of parts during additive manufacturing are essential. The subject of this review is in-situ process monitoring for material extrusion additive manufacturing. The...
Article
Full-text available
The advancement of micro- and nanostructuring techniques in optics is driven by the demand for continuous miniaturization and the high geometrical accuracy of photonic devices and integrated systems. Here, UV-LED projection photolithography is demonstrated as a simple and low-cost approach for rapid generation of two-dimensional optical micro- and...
Article
Full-text available
The manufacturing technology of thermoelectric materials is laborious and expensive often including complex and time-intensive preparation steps. In this work, a laser sintering process of the oxide-based thermoelectric material Ca3Co4O9 is investigated. Samples based on spray-coated Ca3Co4O9 were prepared and subsequently sintered under various la...
Article
The logistic industry has a steady need for improved positioning of goods to keep commercial success. Next to high accuracy, a low maintenance system is needed to ensure the benefits of automation. While state of the art position determination is done by mechanical, optical, or hydraulic techniques, this research addresses a new approach using lase...
Article
Fabrication technologies for the semiconductor industry have enabled ever smaller electronic components but now face a fundamental limit in their assembly. As the components get smaller and smaller, the difficulty of assembly increases. At the same time, the number of components per circuit board area is growing, as is the case with LED displays. T...
Article
Optical networks can carry significantly higher data rates than their equivalent electrical systems. Because of their unique properties and constraints, optical networks have their own design rules. In this paper, an algorithm for the optimization of optical networks is presented. In addition, an optimized optical decimal-binary converter is flexog...
Article
Duplex stainless steels are used in many application fields due to their outstanding performance with respect to strength, toughness, and corrosion resistance. These properties are based on a microstructure proportion of at least a proportion of 30% austenite. To meet the requirements of the microstructure and a high productivity, a high-power and...
Article
Fusion joining of stainless steel to copper without a filler material for pipe processing proves itself to be challenging due to the very different material properties of the joining partners and very heterogeneous characteristics in the weld metal due to different mixing ratios. One of the most common weld defects in this material combination is s...
Article
Adhesive bonding of plastic components is a well-established process for various applications. Specifically for thermoplastic parts, surface pre-treatment is required to achieve optimum bonding quality. However, automated surface pre-treatment is not established yet. Reasons are missing process monitoring and significant challenges arising from con...
Article
The properties of glass (e.g., transparency, chemical and thermal inertness) are advantageous for optical, microfluidic, and chemical applications. Additive manufacturing allows the creation of complex geometries and novel functionalities. In contrast to metals and polymers, there are limited options for digitally creating transparent glass geometr...
Article
Cracking as one of the most common weld defects for joining dissimilar metals can lead to challenges as lack of mechanical properties, lack of joint tightness, lowered electrical conductivity or can be a point of attack for corrosion. Joints between stainless steel and copper also suffer from weld metal cracking which is caused by the effect of liq...
Article
To produce polymer optical fibers in research environments, a flexible cladding material-application process is required. Further, to functionalize the waveguide, the fiber core-production step needs to be separated from the cladding application, contrasting conventional polymer optical fiber production processes. In this study, we developed a solu...
Article
In der Medizintechnik, in der komplexe und patientenindividuelle Produkte hergestellt werden, hat sich die Additive Fertigung etabliert. Da die Prozesse der Additiven Fertigung sensibel auf Veränderungen der Prozessparameter und Umgebungsbedingungen reagieren, sind Qualitätssicherungsmaßnahmen ein zentraler Faktor innerhalb der Produktion. In diese...
Article
Full-text available
We report on a novel bend sensor with high flexibility and elasticity based on Bragg grating structures in polymer optical fibers to detect bending for the measurement of movement. The concept is very simple and relies on the inscription of eccentrical Bragg gratings into multimode graded-index polymer optical fibers via contact exposure with a kry...
Conference Paper
Additive manufacturing is established for the production of polymer and metal structures in many branches of industry. For glass materials, the feasibility of additive manufacturing was recently demonstrated. The Laser Glass Deposition (LGD) is one of the methods to manufacture glass components on a glass substrate with a CO2 Laser. Fused silica fi...
Conference Paper
Full-text available
Accelerated by political programs, such as the nuclear phase-out in Germany which scheduled for the end of 2022, the number of nuclear power plants reaching their lifetime steadily increases [1]. Worldwide, 442 power plants are active, while 54 are currently under construction. In addition, 119 power plants are in planning, indicating, that there w...
Article
Full-text available
This article discusses the relevance of in situ quality assurance in metal additive manufacturing for cost-efficient product qualification. It presents an approach for monitoring the laser powder bed fusion (LPBF) process using an area-scan hyperspectral camera to predict the surface roughness R z with the help of a convolutional neural network. Th...
Article
The drilling of carbon fiber reinforced plastic (CFRP) components is a preliminary step within the assembly of airplanes or cars. The usage of CFRP brings along different challenges and opportunities due to the heterogeneous material characteristics. Laser cutting of thermoplastic composites can lead to distinctive heat affected zones (HAZs) if the...
Article
Kleinskalige modulare Fördertechnik ermöglicht es, mehrere Förderaufgaben gleichzeitig und auf kleinstem Raum durchzuführen, und bietet so ein großes Potenzial zur Flexibilisierung und Effizienzsteigerung von Förderanlagen. Aktuell existiert keine einfach anwendbare Methode, die Unternehmen dabei unterstützt, diese neuartige Fördertechnik auf Proze...
Article
Full-text available
Mankind is setting to colonize space, for which the manufacturing of habitats, tools, spare parts and other infrastructure is required. Commercial manufacturing processes are already well engineered under standard conditions on Earth, which means under Earth’s gravity and atmosphere. Based on the literature review, additive manufacturing under luna...
Article
Full-text available
This paper introduces a new manufacturing process for vertical interconnect accesses (VIA). In contrast to industrially established VIA metallization technologies, the presented approach takes place without any chemical plating by combining copper ink and epoxy insulator coating with CO2 laser processing for VIA drilling and copper ink sintering. T...
Article
Design studies for the next generation of interferometric gravitational wave detectors propose the use of low-noise single-frequency high power laser sources at 1064 nm. Fiber amplifiers are a promising design option because of their high output power and excellent optical beam properties. We performed filled-aperture coherent beam combining with i...
Conference Paper
Printing polymer optical waveguides by means of combined printing processes has proven to be a challenging but effective way of producing waveguides with a loss less than 0.3dB/cm. In order to evaluate the optical performance of the produced waveguides, optical simulations have been carried out. In this work we show the influence on the optical per...
Article
Full-text available
Additive manufacturing (AM) has become increasingly important over the last decade and the quality of the products generated with AM technology has strongly improved. The most common metals that are processed by AM techniques are steel, titanium (Ti) or aluminum (Al) alloys. However, the proportion of magnesium (Mg) in AM is still negligible, possi...
Article
This paper describes the research conducted on the automation for a UV laser-based surface pretreatment of fiber-reinforced composites in order to improve adhesive bonding conditions. In a preceding process step, a laser-line-triangulation system gathered inline information on a composite part’s surface like topology and location of surface contami...
Article
To improve printing results, a printing form can be functionalized and the material transferring behavior can be adjusted. In this work, a flexographic printing form is divided into three different areas: first the elevated, material transferring structures (1); second the rising edges between the printing form substrate and the elevated structures...
Article
Full-text available
Locally adapted properties within a machine component offer opportunities to increase the performance of a component by using high strenght materials where they are needed. The economic production of such hybrid components on the other hand represents a major challenge. The new tailored forming process chain, which is developed within the collabora...
Article
Full-text available
The paper at hand presents a definition of autonomous intralogistics systems and a classification of intralogistics systems with regard to their degree of autonomy. Intralogistics − a complex interplay of different logistics functions − covers the organization, control, execution and optimization of internal material and information flows. Over the...
Article
Fiber-reinforced plastics (FRP) are widely used in the automotive industry due to their lightweight construction potential. Especially, injection-molded components are very popular because of their short cycle times. Unfortunately, this manufacturing process results in some disadvantages for delayed adhesive bonding. On the one hand, such thermopla...
Article
Material processing and material transport systems on Earth are designed for Earth's gravity and atmosphere. In order to pave the way for the future colonization of space, production technologies and transport systems are an essential factor in reducing costs and logistical efforts, such as in-situ resource utilization (ISRU). Laser-based additive...
Chapter
Elektrohängebahnen sind schienengeführte, flurfrei angeordnete Transportsysteme mit einzeln angetriebenen Fahrzeugen [1]. Hierdurch ist ein reversierbarer Betrieb möglich. Sie dienen zur Verbindung einer oder mehrerer Quellen mit einer oder mehreren Senken sowie zum Puffern und Sortieren von Stückgütern. Elektrohängebahnen bestehen aus den Systemko...
Chapter
In der automatisierten Materialflusstechnik übernehmen Steuerungen die Aufgabe, Bewegungen von Gütern in Anlagen zeitlich und räumlich zu koordinieren. Gerätetechnisch unterscheidet man die Steuerungen nach der Komplexität ihres Aufbaus und der Art der Programmierung. Speicherprogrammierbare Steuerungen (SPS) nach IEC 61131, in vernetzten und hiera...
Chapter
Definition der Stetigförderer, Übersicht, Einteilung und Vorteile (s. Kap. 14, Abschn. 14.1.3). Aus der stetigen Fördergutbewegung (eventuell mit wechselnder Geschwindigkeit oder im Takt) resultiert ein Gutstrom, durch dessen Stärke die Leistungsfähigkeit der unterschiedlichen Förderprinzipe und Fördermittel bestimmt wird. Für seine Berechnung ist...
Chapter
In diesem Artikel stellen wir kleinskalige, cyber-physische Fördertechnik am Beispiel einer Fördermatrix vor. Diese Fördermatrix wird modular aus einzelnen Fördermodulen zusammengesetzt, die kleiner als die zu transportierenden Pakete sind. Die Fördermatrix ist in der Lage, verschiedene intralogistische Funktionen wie den Transport, die Rotation, d...
Chapter
Dieser Beitrag zeigt, wie die von Menschen bekannte Flexibilität und Anpassungsfähigkeit gegenüber veränderten Umgebungsbedingungen, die sich in den kognitiven Eigenschaften der Menschen widerspiegelt, auf Flurförderzeuge in der Intralogistik übertragen werden kann. Als Beispiele für die Umsetzung von Industrie 4.0 in der Intralogistik werden Techn...
Conference Paper
Additive manufacturing of thermoplastics or metals is a well approved sustainable process for obtaining rapidly precise and individual technical components. Except for crosslinked silicone rubber or thermoplastic elastomers, there is no way of manufacturing elastomers. Based on the development of the Additive Manufacturing of Elastomers (AME) – pro...
Article
Full-text available
Hybrid cylindrical roller thrust bearing washers of type 81212 were manufactured by tailored forming. An AISI 1022M base material, featuring a sufficient strength for structural loads, was cladded with the bearing steel AISI 52100 by plasma transferred arc welding (PTA). Though AISI 52100 is generally regarded as non-weldable, it could be applied a...
Conference Paper
In the aviation industry, a major market for carbon fibre reinforced plastics (CFRP), more than 34.000 drilling operations are performed throughout the assembly process of an Airbus A350 section 13/14 only. Additionally, a continuous pressure for cost and time optimization exists within the manufacturing process. The quality requirements in the avi...