High Speed Laser Micro Drilling for Aerospace Applications

AbstractTo realize a reduced fuel consumption of civil jet transport aircrafts, hybrid laminar flow control (HLFC) is a key technology in aerospace industry. For drag reduction caused by boundary layer suction, small holes at the leading edges of the aircraft wings and tail planes are needed. Much effort has been spend in drilling of small holes into different materials. Nevertheless, the economically drilling of small holes in the range of 50 to 100μm in diameter on large areas is up to date crucial. Apart from processing time this is also due to the demand of close tolerances in case of suction holes. Additionally, minimization of the thermal distortion when drilling large areas gets more challenging. This paper deals with the transfer of the laser drilling process to an adequate system technology for the fabrication of large suction inserts using a short pulsed fiber laser with a power of 200W at a pulse repetition rate of 200kHz. The laser combined with a galvanic scanner and a plane field optic leads to a precise and fast drilling over an area of 100mm x 100mm. Using a precise stage several of these drilling fields can be placed side by side to machine the complete panel area. The amount of drilled through-going holes and their roundness as well as the distortion of the panel is influenced by the applied drilling sequence and energy input. As a result, round micro holes down to 30μm in diameter can be produced with a drilling rate of more than 400 holes per second in 0.8mm thick titanium sheets

Корпус домашнего фотобиореактора

Объектом исследования является корпус бытового фотобиореактора для выращивания микроводорослей. Цель работы – создание дизайна корпуса фотобиореактора для выращивания микроводорослей в домашних условиях. В процессе исследования проводились теоретические исследования, разработка концепта и вариантов корпуса прибора, трехмерное моделирование и прототипирование.The object of the research is the housing of a domestic photobioreactor for growing microalgae. The goal of the work is to create a design of the housing of the photobioreactor for growing microalgae at home. In the course of the research, theoretical studies, development of the concept and variants of the instrument case, three-dimensional modeling and prototyping were carried out

Micro metal forming

Micro Metal Forming, i. e. forming of parts and features with dimensions below 1 mm, is a young area of research in the wide field of metal forming technologies, expanding the limits for applying metal forming towards micro technology. The essential challenges arise from the reduced geometrical size and the increased lot size. In order to enable potential users to apply micro metal forming in production, information about the following topics are given: tribological behavior: friction between tool and work piece as well as tool wear mechanical behavior: strength and formability of the work piece material, durability of the work pieces size effects: basic description of effects occurring due to the fact, that the quantitative relation between different features changes with decreasing size process windows and limits for forming processes tool making methods numerical modeling of processes and process chains quality assurance and metrology All topics are discussed with respect to the questions relevant to micro metal forming. The description comprises information from actual research and the young history of this technology branch to be used by students, scientists and engineers in industry who already have a background in metal forming and like to expand their knowledge towards miniaturization

8. Kolloquium Mikroproduktion: Fachbeiträge

Um die speziellen Anforderungen der Mikrotechnik auf eine systematische Grundlage zu stellen und so eine beherrschte, auf den Mikrobereich zugeschnittene Produktion zu ermöglichen, wurden bzw. werden von der Deutschen Forschungsgemeinschaft (DFG) mehrere koordinierte Forschungsvorhaben gefördert. Das Kolloquium Mikroproduktion findet seit 2003 im Zweijahresrhythmus statt und dient der Vernetzung der Standorte. Zielgruppe sind Forscher und industrielle Anwender der Mikrotechnik. Im Rahmen des 8. Kolloquiums wurden Inhalte einer Vielzahl von aktuellen Folgeprojekten bereits abgeschlossener koordinierter Forschungsvorhaben sowie dem gastgebenden Sonderforschungsbereich 747 Mikrokaltumformen - Prozesse, Charakterisierung, Optimierung in Bremen thematisiert. In diesem Tagungsband sind wesentliche aktuelle wissenschaftliche Ergebnisse in peer-reviewten Beiträgen dokumentiert, die im Rahmen des gemeinsamen Kolloquiums am 27. und 28. November 2017 in Bremen vorgestellt wurden.Breme

Pulvermetallurgische Verarbeitung eines übereutektoiden verschleißfesten Stahls

Bei der pulvermetallurgischen Herstellung von Massenformteilen stellen die Werkstoffkosten einen wesentlichen Faktor für die Gesamtkosten eines Produkts dar. In dieser Arbeit wurde daher ein kostengünstiger Werkstoff gewählt, der durch einen systematisch optimierten Herstellungsprozess so verarbeitet wurde, dass das sich ergebende Gefüge das geforderte Eigenschaftsprofil aufweist. Zu diesen Eigenschaften gehörten Forderungen an die Zug- und Druckfestigkeit, den Verschleißwiderstand und die Arbeitsgenauigkeit. Für die Untersuchungen wurde eine Fertigungslinie für die pu1vermetallurgische Produktion verschiedener Probekörper, darunter auch PKW-Nocken als Musterbauteil, aufgebaut. Für die Verschleißprüfung wurden verschiedene Prüfstände entwickelt, mit denen im Sinne einer Verschleißprüfkette die Prüfzeiten um 99% gegenüber dem Bauteilversuch gekürzt werden konnten. Durch Anpassung der Gründichte, des Temperatur-Zeit-Profils und der Sinteratmosphäre an die Eigenheiten eines übereutektoiden Stahls wird bei einer Hochtemperatursinterung in nur 20 min Sinterzeit die theoretische Dichte bei gleichzeitig sehr homogenem Gefüge erreicht. Dieses Gefüge führt zu den geforderten Bauteileigenschaften. So liegt die Druckfestigkeit bei über 2,4 GPa und der Verschleißwiderstand im Nockenversuch über dem des oberflächenumgeschmolzenen Gusses.Within mass production of mouldings by powder metallurgy the material costs are an important factor concerning the total product costs. In the scope of this work, a low cost material was chosen to be manufactured by systematically optimizing the manufacturing processes, thus the resulting microstructure meets the technological requirements. These properties comprise the tensile as well as the compressive strength, the wear resistance and the process accuracy. For the investigations a powder metallurgical production line was developed allowing for varying specimen geometry, among those automotive camshaft elements. Different test stands were developed for the wear resistance tests, enabling to shorten the total testing time by means of a testing chain at 99 per cent with respect to conventional component tests. Adapting the density of the specimen, the temperature-time profile and the sintering atmosphere to the properties of the over-eutectical steel, the theoretical density is reached by high-temperature sintering within just 20 minutes sintering time, providing homogeneous microstructure at the same time. This microstructure leads to the mechanical requirements of the component. The compressive strength succeeds 2.4 GPa. The wear resistance within camshaft element testing is improved in comparison to near-surface remelt iron

Surface accuracy achieved by upsetting of preforms generated by laser rod end melting

Cold forming generally allows the reproduction of parts with a high production rate and low waste of material. For this reason, many small parts for example of the body of a smartphone undergo at least one forming operation during their fabrication, e.g. screws, brackets or springs. However, when the size of forming products is reduced to the micro range, size effects appear and affect the forming process. One size effect leads to the fact that conventional multi stage upsetting processes cannot be scaled to micro range accordingly. As a consequence, the maximum achievable upset ratio decreases from 2.3 in macro range to values below 2 in micro range. This reduces the efficiency of the upsetting process significantly as more upsetting stages have to be carried out to reach the desired shape of the forming product. A very promising approach to reduce required forming stages is the laser rod end melting process which takes advantage of a size effect. Herein, the lower end of a rod is melted by the energy of a laser beam. The molten part of the rod automatically forms spherical due to surface tension. This droplet-shaped part is called “preform”. After total cooling, the preform is upset within a single stage cold forming operation to achieve the desired shape. In this paper, results of the upsetting operation with regard to surface accuracy of the forming product are presented. It is shown that surface characteristics with dimensions as small as 500 nm can be reasonably reproduced