Lars Schönemann

University of Würzburg

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E. Brinksmeier

Leibniz-Institut für Werkstofforientierte Technologien - IWT

Oltmann Riemer

University of Bremen

Bernd Kuhfuß

University of Bremen

Bernhard Karpuschewski

Leibniz-Institut für Werkstofforientierte Technologien - IWT

Christian Schenck

University of Bremen

Berend Denkena

Leibniz University Hannover

Ralf Gläbe

Hochschule Bremen

W. Preuß

University of Bremen

Daniel Berger

University of Bremen

Lasse Langstädtler

University of Bremen

Cooperative Institutions

University of Bremen

Leibniz-Institut für Werkstofforientierte Technologien - IWT

Staats- und Universitätsbibliothek Bremen

University of Würzburg

Leibniz University Hannover

Nanjing University of Science and Technology

Deutsche Post (Germany)

Hong Kong Polytechnic University

Institute for Applied Systems Technology Bremen

Fraunhofer Institute for Machine Tools and Forming Technology

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Research Field

Microstructuring of Surfaces for Bio-Medical Applications

Advanced materials research (2014)

E. Brinksmeier Oltmann Riemer Lars Schönemann Han Zheng Florian Böhmermann

In recent years microfluidic devices became of great interest, as they offer a wide range of bio-analytical and fluid processing applications through the utilization of size effects. Especially a mass manufacturing of disposable polymeric microfluidic devices by hot embossing or injection molding is expected to have high economic potential. It is known, that channels and areas showing a localized change in wettability can considerably improve fluid processing tasks like mixing or droplet generation. Chemical approaches, like the polymerization of lauryl acrylate, were successfully shown to achieve hydrophobic coatings for micro channels but are not suitable for a mass manufacturing. Since microstructures are known to provide water repellent properties of surfaces, this paper focuses on the applicability of diamond grooving and Diamond Micro Chiseling (DMC) processes for the manufacture of microstructured areas in brass molds inserts, in order to achieve hydrophobic properties of their replica. Major design features of structures, like a height range of 6 to 16μm or aspect ratios in between 0.5 and 3.2 are derived from the natural example of the lotus leaf. Molding is carried out by using a two component silicone filler. The performance of the replicated hydrophobic surfaces is evaluated by droplet contact angle measurements. After presenting methodology and results, the paper will conclude on how to transfer the investigated microstructuring methods to the manufacture of mold inserts for the replication of polymeric microfluidic chips with localized hydrophobic areas and channels.

Molding (decorative)

Embossing

Lotus effect

Replication

10.4028/www.scientific.net/amr.907.213

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Citations (2)

High performance cutting for ultra-precision machining

International Journal of Nanomanufacturing (2015)

E. Brinksmeier Oltmann Riemer Lars Schönemann

This keynote paper will present new approaches for high performance ultra-precision machining that are developed to overcome typical shortcomings of the currently applied machining process. Firstly, ultra-precision machining is compared to conventional machining and approaches commonly used in the latter one are evaluated regarding their applicability for ultra-precision machining. Secondly, results for applying high speed spindles will be demonstrated and their effect on the acting process forces will be discussed. The use of high speed spindles in ultra-precision machining, however, increases the need for faster and more precise balancing procedures. Here, new concepts for expanding the sensitivity of unbalance measurements by deliberately reducing the stiffness of the spindle mounting are presented.

10.1504/ijnm.2015.075228

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Citations (7)

Digital surface twin for ultra-precision high performance cutting

Precision Engineering (2022)

Lars Schönemann Oltmann Riemer Bernhard Karpuschewski Per Schreiber Heinrich Klemme

10.1016/j.precisioneng.2022.06.010

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Citations (8)

Thermo-mechanical tool setting mechanism for ultra-precision milling with multiple cutting edges

Precision Engineering (2018)

Lars Schönemann Oltmann Riemer

Nanometre

Machine tool

Precision engineering

10.1016/j.precisioneng.2018.09.003

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Citations (9)

Diamond Micro Chiseling of large-scale retroreflective arrays

Precision Engineering (2012)

E. Brinksmeier Ralf Gläbe Lars Schönemann

Retroreflector

Cube (algebra)

Structuring

10.1016/j.precisioneng.2012.06.001

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Citations (61)

Ultra-precision High Performance Cutting

Lecture notes in production engineering (2022)

E. Brinksmeier Lars Schönemann

10.1007/978-3-030-83765-5

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Citations (1)

Electromagnetic Embossing of Optical Microstructures with High Aspect Ratios in Thin Aluminum Sheets

ESAFORM 2021 (2021)

Julian Heidhoff Björn Beckschwarte Oltmann Riemer Lars Schönemann Marius Herrmann

Electromagnetic embossing enables the transfer of surface structures from forming dies to metal sheets at high forming speeds. For this purpose, the contactless forming force is provided by means of a magnetic field of a tool coil which interacts with an eddy current in the workpiece. In thin sheets which are completely penetrated by the magnetic field, the resulting Lorentz forces act as body forces that accelerate the workpiece onto the forming die. In addition to the body forces, also high strain rates can support the embossing of thin sheets. This investigation deals with the embossing of pyramidal structures in the submillimeter range and an aspect ratio of about 1 into thin aluminum sheets (3.0255 / Al99,5). In order to quantify the reproduced microstructures, their extent is determined by means of a lateral analysis. From this, the replicated height is derived. Up to now it has been possible to partially reproduce microstructures with a large aspect ratio in thin sheets. In addition, the changing surface roughness of the sheets is taken into account. Before embossing, the sheets exhibit a relatively rough surface with a rolled texture, which is smoothed by the impulse forming with an optical forming die. This study reveals basic approaches for the electromagnetic embossing of optical microstructures.

Embossing

Electromagnetic forming

10.25518/esaform21.4337

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Citations (3)

Ultrapräzise Hochgeschwindigkeitsbearbeitung*/Ultra-precision high performance cutting – Part 2

wt Werkstattstechnik online (2015)

Lars Schönemann Nesrine Sassi Rudolf Krüger Arne Bloem Berend Denkena

Die ultrapräzise Fräsbearbeitung ist eine flexible Möglichkeit, um optische Freiformflächen herzustellen. Aufgrund der hohen Genauigkeitsanforderungen sind die anwendbaren Vorschub- und Schnittgeschwindigkeiten allerdings beschränkt. Deshalb werden hier zwei neue Ansätze zur Wirtschaftlichkeitssteigerung präsentiert: der Einsatz ultrapräziser Magnetführungen sowie die modellbasierte Vorhersage von Bahnabweichungen und deren Kompensation mithilfe der elektromagnetischen Führung (Teil 1: wt 6-2015, S. 366–370).   Ultra-precision milling is a flexible process for generating optical freeform surfaces. However, due to the tight tolerances of such parts, only low feedrates and cutting velocities are applied. This publication presents two novel approaches to increase the productivity of ultra-precision machining: the use of electromagnetic guideways and the model-based prediction of path deviations and their compensation using the electromagnetic guideway.

Machine tool

10.37544/1436-4980-2015-07-08-27

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Citations (0)

Micro Chiseling of Retroreflective Arrays

Micro/Nano technologies (2018)

Lars Schönemann E. Brinksmeier

Retroreflector

Micrometer

Cube (algebra)

10.1007/978-981-13-0098-1_1

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Citations (1)

Synergistic approaches to ultra-precision high performance cutting

CIRP journal of manufacturing science and technology (2020)

Lars Schönemann Daniel Berger Timo Dörgeloh Oltmann Riemer E. Brinksmeier

Diamond milling allows for the flexible production of optical and high precision parts, but suffers from poor setup and production speeds. This paper presents recent advances that aim towards achieving high performance (HPC) and high speed cutting (HSC) in ultra-precision machining. After a short introduction, the benefits of high speed cutting for both metals and brittle-hard materials are shown. Thereafter, novel mechatronic devices are presented that enable an automated balancing of the applied air bearing spindles and the application of multiple diamond tools on one tool holder and by thus, contribute to HPC. These developments are supplemented by a novel linear guiding system based on electromagnatic levitation that, along with a dedicated model-based control system, enables fast and precise movements of the machine tool. After presenting the recent developments in detail, their synergistic performance is assessed and an outlook to future developments is given.

Machine tool

10.1016/j.cirpj.2019.12.001

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Citations (10)