Hybrid additive manufacturing : improved large scale additive manufacturing by means of laser tempering. - In: PhotonicsViews, ISSN 2626-1308, Bd. 19 (2022), 5, S. 47-51
Large-scale additive manufacturing (LSAM) is an additive manufacturing process based on the principles of fused filament fabrication but with significantly higher material deposition rates. The novel hybrid process shown in this paper combines LSAM with a laser beam heat treatment. The structure and mechanical properties of parts are improved due to significantly decreased void sizes. The following article details investigations into the vertical and lateral remelting of strands as well as the utilization of a mirror system, which enables beam guidance according to the machine's printing path.
A novel concept for 5D nanopositioning, nanomeasuring and nanofabrication machines :
Ein neuartiges Konzept für 5D Nanopositionier-, Nanomess-, und Nanofabrikationsmaschinen. - In: Technisches Messen, ISSN 2196-7113, Bd. 89 (2022), 9, S. 634-643
In den vergangenen Jahren wurden an der TU-Ilmenau zahlreiche Entwicklungen im Bereich der Nanopositionier- und Nanomesstechnik realisiert. Insbesondere die NMM-1 [Gerd Jäger, Eberhard Manske, Tino Hausotte, Jans-Joachim Büchner, Nanomessmaschine zur abbefehlerfreien Koordinatenmessung, tm - Technisches Messen, 67(7-8), 2000] sowie die NPMM-200 [Eberhard Manske, Gerd Jäger, Tino Hausotte, Felix Balzer, Nanopositioning and Nanomeasuring Machine NPMM-200 - sub-nanometre resolution and highest accuracy in extended macroscopic working areas, euspen’s 17th International Conference, 2017] stellen ein Novum auf dem Gebiet der Koordinatenmesstechnik mit Nanometerpräzision unter Einhaltung des Abbe-Komparatorprinzips [Ernst Abbe, Messaparate für Physiker, Zeitschrift für Instrumentenkunde, 10:446-448, 1890] dar. Ausgehend von diesen Errungenschaften besteht ein nächster Schritt im Messen und Fabrizieren auf stark gekrümmten, asphärischen, oder freigeformten Oberflächen. Vor jenem Hintergrund wird im folgenden Artikel ein Konzept für ein zweiachsiges Rotationsmodul vorgestellt. Dieses dient als Erweiterung für die NMM-1 und ermöglicht über das kartesische Messvolumen von hinaus zusätzlich eine Rotation des Tools über 360 ˚ um die Hochachse sowie 60 ˚ Neigung. Die Umsetzung erfolgt über eine neuartige sphärische Parallelkinematik. Mit Hilfe eines interferometrischen In-Situ-Referenzmesssystems können die während der Rotationsbewegungen auftretenden translatorischen Positionsabweichungen detektiert werden. Erste Untersuchungen an einem Prototypenaufbau erbringen den Funktionsnachweis des Referenzmesssystems über den gesamten adressierbaren Winkelbereich.
Design of an enhanced mechanism for a new Kibble balance directly traceable to the quantum SI. - In: EPJ Techniques and Instrumentation, ISSN 2195-7045, Bd. 9 (2022), 1, 7, S. 1-18
The "Quantum Electro-Mechanical Metrology Suite" (QEMMS) is being designed and built at the National Institute of Standards and Technology. It includes a Kibble balance, a graphene quantum Hall resistance array and a Josephson voltage system, so that it is a new primary standard for the unit of mass, the kilogram, directly traceable to the International System of Units (SI) based on quantum constants. We are targeting a measurement range of 10 g to 200 g and optimize the design for a relative combined uncertainty of for masses of 100 g. QEMMS will be developed as an open hardware and software design. In this article, we focus on the design of an enhanced moving and weighing mechanism for the QEMMS based on flexure pivots.
Aerostatically sealed chamber as a robust aerostatic bearing. - In: Tribology international, ISSN 0301-679X, Bd. 173 (2022), 107614, S. 1-10
Aerostatic bearings are typically used in ultra precision and high speed applications in controlled environments. The present study expands this operating domain. The present study experimentally investigates the performance and feasibility of a novel design for a robust air bearing consisting of an aerostatically sealed pressurized volume. A suitable operating domain for the bearing system was characterized based on measurements of the load capacity, friction moment, chamber flow, and seal flow rate at various opposing surface run-outs and supply pressures. The highest measured load capacity was 18.86 kN at 0.330 mm run-out, and decreased to 12.22 kN load at 3.804 mm run-out. The study provided corroborative evidence on the feasibility of the proposed chamber based bearing design.
Adjustment concept for compensating for stiffness and tilt sensitivity of a novel monolithic electromagnetic force compensation (EMFC) weighing cell. - In: Journal of sensors and sensor systems, ISSN 2194-878X, Bd. 11 (2022), 1, S. 109-116
This paper describes the new adjustment concept of novel planar, monolithic, high-precision electromagnetic force compensation weighing cells. The concept allows the stiffness and the tilt sensitivity of the compliant mechanisms that are dependent on the nominal load on the weighing pan to be adjusted to an optimum. The new mechanism is set up and adjusted according to the developed mechanical model. For evaluation of the concept the system is tested on a high-precision tilt table and under high vacuum conditions in the environment of a commercially available mass comparator.
Foreword to the special issue on "Tip- and laser-based 3D nanofabrication in extended macroscopic working areas". - In: Nanomanufacturing and metrology, ISSN 2520-8128, Bd. 4 (2021), 3, S. 131
Development and implementation of a rotating nanoimprint lithography tool for orthogonal imprinting on edges of curved surfaces. - In: Nanomanufacturing and metrology, ISSN 2520-8128, Bd. 4 (2021), 3, S. 175-180
Uniform molding and demolding of structures on highly curved surfaces through conformal contact is a crucial yet often-overlooked aspect of nanoimprint lithography (NIL). This study describes the development of a NIL tool and its integration into a nanopositioning and nanomeasuring machine to achieve high-precision orthogonal molding and demolding for soft ultraviolet-assisted NIL (soft UV-NIL). The process was implemented primarily on the edges of highly curved plano-convex substrates to demonstrate structure uniformity on the edges. High-resolution nanostructures of sub-200-nm lateral dimension and microstructures in the range of tens of microns were imprinted. However, the nanostructures on the edges of the large, curved substrates were difficult to characterize precisely. Therefore, microstructures were used to measure the structure fidelity and were characterized using profilometry, white light interferometry, and confocal laser scanning microscopy. Regardless of the restricted imaging capabilities at high inclinations for high-resolution nanostructures, the scanning electron microscope (SEM) imaging of the structures on top of the lens substrate and at an inclination of 45˚ was performed. The micro and nanostructures were successfully imprinted on the edges of the plano-convex lens at angles of 45˚, 60˚,and 90˚ from the center of rotation of the rotating NIL tool. The method enables precise imprinting at high inclinations, thereby presenting a different approach to soft UV-NIL on curved surfaces.
Tip- and laser-based 3D nanofabrication in extended macroscopic working areas. - In: Nanomanufacturing and metrology, ISSN 2520-8128, Bd. 4 (2021), 3, S. 132-148
The field of optical lithography is subject to intense research and has gained enormous improvement. However, the effort necessary for creating structures at the size of 20 nm and below is considerable using conventional technologies. This effort and the resulting financial requirements can only be tackled by few global companies and thus a paradigm change for the semiconductor industry is conceivable: custom design and solutions for specific applications will dominate future development (Fritze in: Panning EM, Liddle JA (eds) Novel patterning technologies. International society for optics and photonics. SPIE, Bellingham, 2021. https://doi.org/10.1117/12.2593229). For this reason, new aspects arise for future lithography, which is why enormous effort has been directed to the development of alternative fabrication technologies. Yet, the technologies emerging from this process, which are promising for coping with the current resolution and accuracy challenges, are only demonstrated as a proof-of-concept on a lab scale of several square micrometers. Such scale is not adequate for the requirements of modern lithography; therefore, there is the need for new and alternative cross-scale solutions to further advance the possibilities of unconventional nanotechnologies. Similar challenges arise because of the technical progress in various other fields, realizing new and unique functionalities based on nanoscale effects, e.g., in nanophotonics, quantum computing, energy harvesting, and life sciences. Experimental platforms for basic research in the field of scale-spanning nanomeasuring and nanofabrication are necessary for these tasks, which are available at the Technische Universität Ilmenau in the form of nanopositioning and nanomeasuring (NPM) machines. With this equipment, the limits of technical structurability are explored for high-performance tip-based and laser-based processes for enabling real 3D nanofabrication with the highest precision in an adequate working range of several thousand cubic millimeters.
High-precision and large-stroke XY micropositioning stage based on serially arranged compliant mechanisms with flexure hinges. - In: Precision engineering, Bd. 72 (2021), S. 469-479
Compliant mechanisms are state of the art in micropositioning stages due to their many beneficial features. However, their design usually compromises between motion range, motion accuracy and design space, while mechanisms with distributed compliance are mostly applied. The further use of flexure hinges with common notch shapes strongly limits the stroke in existing high-precision motion systems. Therefore, this paper presents a high-precision compliant XY micropositioning stage with flexure hinges capable of realizing a motion range of ± 10 mm along both axes. The stage is based on a novel plane-guidance mechanism, which is optimized to realize a precise rectilinear motion of the coupler link while keeping the rotation angles of all hinges below 5˚. The XY motion is then achieved by coupling two of these mechanisms in a serial arrangement. Next, the synthesis of the monolithic XY stage is realized by replacing all revolute joints of the rigid-body model with flexure hinges using optimized power function notch shapes. Emphasis is also placed on the embodiment design of the stage and the actuator integration to minimize possible error sources. Finally, the quasi-static behavior of the compliant stage is characterized by a simulation with a 3D FEM model and by an experimental investigation of a prototype. According to the results, the developed compliant XY micropositioning stage achieves a maximum positioning deviation of less than 10 [my]m in both axes and a yaw error of less than 100 [my]rad over a working range of 20 mm × 20 mm with a comparably compact design of the compliant mechanism of 224 mm × 254 mm.
Experimental setup for the investigation of reproducibility of novel tool changing systems in nanofabrication machines. - In: Nanomanufacturing and metrology, ISSN 2520-8128, Bd. 4 (2021), 3, S. 181-189
Nanomeasuring machines developed at the Technische Universität Ilmenau enable three-dimensional measurements and manufacturing processes with the lowest uncertainties. Due to the requirements for these processes, a highly reproducible and long-term stable tool changing system is needed. For this purpose, kinematically determined couplings are widely used. The state-of-the-art investigations on those are not sufficient for the highest demands on the reproducibility required for this application. A theoretical determination of the reproducibility based on analytical or numerical methods is possible, however not in the desired nanometer range. Due to this, a measurement setup for the determination of the reproducibility in five degrees of freedom with nanometer uncertainty was developed. First, potential measuring devices are systematically examined and measurement principles were developed out of this. A three-dimensional vector-based uncertainty analysis is performed to prove the feasibility of the measurement principle and provides a basis for further design. As a result, a translatory measurement uncertainty of 10 nm and a rotatory uncertainty of 11 nrad can be reached. Afterwards, the measurement setup is designed, focusing on the metrological frame and the lift-off device. The developed setup exceeds the uncertainties of the measurement setups presented in the state-of-the-art by an order of magnitude, allowing new in-depth investigations of the reproducibility of kinematic couplings.