Benjamin Kirsch

Application of Ultra-Small Micro Grinding and Micro Milling Tools: Possibilities and Limitations

Current demands for flexible, individual microstructures in high quality result in high requirements for micro tools. As the tool size defines the minimum structure size, ultra-small tools are needed. To achieve tool diameters of 50 µm and lower, we investigate the complete manufacturing chain of micro machining. From the development of the machine tools and components needed to produce and apply the micro tools, the micro tools themselves, as well as the micro machining processes. Machine tools are developed with the possibility of producing the micro geometry (cutting edge design) of micro tools as well as plating processes to produce super abrasive micro grinding tools. Applying these setups, we are able to produce ultra-small micro grinding and micro milling tools with typical diameters of 50 µm and down to 4 µm. However, the application of such tools is very challenging. The article presents possibilities and limitations in manufacturing the micro tools themselves as well as microstructures made with these tools. A special emphasis will be on the influence of the tool substrate in micro milling and grain sizes in micro grinding.

Compact Air Bearing Spindles for Desktop Sized Machine Tools

In this paper two new small and lightweight spindles for the implementation in desktop sized machine tools are introduced. In both spindles, the tool shaft with a micro tool on the tip (e.g. micro end mill, micro pencil grinding tool or Electrical Discharge Machining (EDM) electrode) works directly as a rotor and is supported by aerostatic bearings. The spindles are driven via air turbines and reaches high rotational speeds in combination with high rotational accuracies. One spindle was implemented in a desktop-sized machine tool and used for micro machining of titanium and brass. With the high rotational speed of the spindles very high material removal rates can be achieved. Thus, the productivity of the micro machining process is enhanced.

Untersuchung des Verschleißverhaltens von TiB2-beschichteten Mikrofräswerkzeugen

Kurzfassung Beim Einsatz von Mikrofräswerkzeugen kommt es, bedingt durch Größeneffekte, zu erhöhter Reibung und damit erhöhtem Verschleiß. Zusätzlich resultieren aus den geringen Werkzeugdurchmessern niedrige Schnittgeschwindigkeiten, sodass es zu Aufbauschneiden kommen kann. Beides wirkt sich negativ auf die Prozessergebnisgrößen aus und reduziert die Effizienz des Prozesses. Um dies zu minimieren, wurden Mikrofräswerkzeuge (Ø 50 μm) mit einer PVD-Beschichtung versehen und das Einsatzverhalten untersucht.

Effects of Lubrication on the Friction in Nanometric Machining Processes: A Molecular Dynamics Approach

Physical phenomena in a nanometric machining process were studied by molecular dynamics simulations. A cylindrical tool was indented and then moved laterally on an initially flat workpiece. The focus of the study is on the effect of lubrication on the nanoscale. Therefore, the indentation and the scratching were studied both in vacuum and submersed in a lubricant. All materials were modeled by Lennard-Jones truncated and shifted potential sites. It is observed, that in the lubricated case, a substantial part of the cutting edge of the tool is in dry contact with the workpiece. Nevertheless, compared to the dry scenario, the lubrication lowers the coefficient of friction. However, the work which is needed for the indentation and the scratching is not reduced. The processed surface is found to be smoother in the lubricated case. As expected, the lubrication has an important influence on the temperature field observed in the simulation.

Kryogener Kühlschmierstoff auf der Basis von Ethylenglykol

Kurzfassung Die zur Kühlung und Schmierung eingesetzte Kühlstrategie ist für die Produktivität spanender Fertigungsverfahren von hoher Bedeutung. Im Rahmen dieses Beitrags wird eine innovative Kühlstrategie auf der Basis von wässrigen Mono-Ethylenglykol-Lösungen vorgestellt, die zur Steigerungen der Produktivität führen soll. Die Kühlwirkung der neuen Kühlstrategie wird mit einer Trockenbearbeitung und einer kryogenen CO2-Schnee-Kühlung verglichen und zeigt gute Ergebnisse.

Oberflächenerzeugungs-Morphologie-Eigenschafts-Beziehungen

Kurzfassung Bauteiloberflächen sind häufig entscheidend für das Einsatzverhalten und die Lebensdauer technischer Systeme. Unter Bauteiloberfläche werden hier auch die Regionen in unmittelbarer Nähe der Grenze zwischen dem Bauteil und der Umgebung verstanden. Im Sonderforschungsbereich 926 der Deutschen Forschungsgemeinschaft werden an der Technischen Universität Kaiserslautern Oberflächenerzeugungs-Morphologie-Eigenschafts-Beziehungen (OMEB) erarbeitet, die es erlauben, vom Fertigungsverfahren und seinen Prozessparametern direkt auf das Einsatzverhalten eines Bauteils zu schließen.

A model-based approach for the calibration and traceability of the angle resolved scattering light sensor

Within the field of geometric product specification there is a growing need for the application of inline measurement systems. The use of inline measurement requires robust and fast measurement principles. A very robust optical measurement principle is the angle resolved scattering light (ARS) sensor. The ARS sensor provides high precision and high resolution measurement data of technical surfaces because the surface angles are measured as an intensity distribution on a detector instead of measuring a series of discrete height values. However, until now, there were no specific measurement standards for the calibration of the ARS sensor and no traceability was ensured. In this paper, new strategies for the calibration of an ARS sensor are proposed. A new mathematical model for the ARS sensor is introduced. Based on this, two new measurement standards for the calibration of the sensor parameters are derived. These standards are designed with a model-based approach and can calibrate sensor-specific properties of the ARS sensor. The manufacturing of the standards is described and measurement results are provided.

Improved Quality of Drilled Holes in Laminated Carbon Fiber Reinforced Plastics via Laser-Preprocessing

In this paper, a new hybrid process to manufacture holes in laminated carbon fiber reinforced plastics is presented. It combines the advantages of conventional drilling (fast and easy to control) and laser drilling (high entry and exit quality of the holes). It is shown, that considerable improvements of the quality of drilled holes can be achieved via laser-preprocessing.

High-Performance Surface Grinding

This chapter presents experimental as well as modelling and simulation approaches to investigate a high-performance surface grinding process. The complex material removal mechanisms generate transient cutting forces that cover a wide range of excitation frequencies. The generated cutting forces impact the grinding machine and lead to deformations, which depend on the machine’s mechanical properties. In general, these deformations have an influence on the cutting forces. Deformations lead to a change of the depth of cut and, therefore, the cutting forces change. Thus, there are three aspects of great importance: the process, the machine and the process machine interaction. Advances in investigating the process are covered first. Afterwards, a new approach to model the machine, its deformation behavior and the way the machine interacts with the process will be described.

Product-Oriented Sustainability Aspects of Abrasive Processes

Sustainability in manufacturing became more and more important in the last years and, because of scarcity of resources, will become even more important in the future. In a process-oriented view, abrasive processes appear to be the worst manufacturing processes concerning sustainability due to their high required specific energies. In this paper a product-oriented view is proposed, taking the whole Life Cycle of the machined products into account. In doing so, it becomes evident that abrasive processes can enhance sustainability even when investing additional energy during machining.Copyright