Due to the high prices of certified calibration standards the calibration of surface topography measuring systems is a very costly procedure. Therefore, the calibration of these systems is often performed by special laboratories such as the German Calibration Service (DKD). It is one of the objectives of the EU-project SMT4-CT97-2176: "Calibration Standards for Surface Topography Measuring Systems down to Nanometric Range" to produce low-priced calibration standards by means of ultra-precise machining and replication processes for a wide range of applications in the market and thus to contribute to quality assurance in the control of measuring systems.

The conservation of the environment is an increasingly important factor for the metalworking industry. The ECO-Center located at the Institute of Material Science is engaged in further development of machining processes with particular focus on the environmental side of these processes. The support of companies which are looking for more environmental friendly solutions in this area is one of the most important targets of the works. The following contribution deals with the configuration of environmental-conscious machining processes and the problem of the comparison of alternating machining processes concerning their impact on the environment.

Abstract Vor dem Hintergrund der Energieeinsparung gewinnt der Wunsch nach Leichtbaukonstruktionen immer mehr an Bedeutung. Branchen, wie die Luft- und Raumfahrtindustrie, Sportgerätehersteller und der Automobilbau, setzen vermehrt auf den Einsatz von Schichtverbunden. Den Vorteilen hinsichtlich ihrer mechanischen Eigenschaften stehen, bedingt durch die Materialkombinationen oder Prozessvorgaben, Schwierigkeiten in der Fertigung gegenüber. Besonders in der Zerspanung treten Probleme hinsichtlich der Verarbeitung auf. In der vorliegenden Arbeit werden Zerspanuntersuchungen an einem typischen Werkstoffverbund aus kohlenstofffaserverstärktem Kunststoff und Aluminium unter Einsatz von drei verschiedenen Minimalmengenschmierstoffen vorgestellt und mit der Trockenbearbeitung verglichen. Als Bearbeitungsprozess wurde der Prozess Bohren ins Volle durchgeführt. Zur Beurteilung der Prozessqualität wurden die Parameter Vorschubkraft Ff, die gemittelte Rautiefe Rz und die Abweichung der Bohrungsdurchmesser vom Zieldurchmesser D der hergestellten Bohrung herangezogen. Die Ergebnisse zeigen eindeutige Qualitätssteigerungen unter Einsatz der Minimalmengenschmierung. Die verwendeten Schmierstoffe lieferten, in Abhängigkeit ihres chemischen Aufbaus, unterschiedliche Resultate bezüglich der Bewertungskriterien.

Ultra-precision milling with multiple diamond cutting edges—which generally is favorable in terms of economic efficiency—requires an in-process tool setting system that allows for the compensation of alignment and fixation errors. Such a system was designed on the basis of thermal expansion as the main means of actuation. The heat input is generated by infrared light diodes which feed the respective energy to the rotating tool contactlessly. It is controlled in a way that ensures that only a specific portion of the tool holder is illuminated and therefore thermally expanded. By measuring the displacement at a reference plane with a capacitive measurement system and feeding it back to the control system, the actual position of the diamond cutting edge can be precisely set in nanometer range. This chapter gives an overview on the main technical developments for the respective prototype system and presents its performance when used in a machining environment.

Due to the high resulting centrifugal forces, high speed spindles require an extremely well balanced setup. Within this project, an automatic system for precision balancing of air bearing spindles was developed, which has the potential to supersede manual balancing completely and thus reduce setup times considerably. The scientific challenges of this approach are the measurement and compensation of extremely small residual unbalances, which lie below the detection threshold of conventional sensor systems.

Today, the technology of high speed machining (HSM) is well understood and established for conventional turning and milling at high material removal rates. However, this is not the case for ultra-precision processes. Consequently, in this project the mechanisms of high-speed machining in the ultra-precision range were investigated for both, non-ferrous metals as well as brittle-hard semiconductor materials, by diamond turning and milling (i.e. fly-cutting). For both material classes, reduced tool wear, lower cutting forces and most important, superior surface quality were achieved. The reason for the advantageous material removal behavior when applying high cutting speeds is the transition to adiabatic shearing, occurring at high temperatures and beneficial pressure in the contact zone.

Multiscale structured surfaces are a way to provide advanced, otherwise not attainable functionality on a technical part. Applications of such parts can be manifold, and numerous works have already covered the transfer of natural examples into bio-inspired surfaces or the geometrical and functional metrology of such surfaces. After briefly presenting typical functionalities of multiscale structured surfaces, this keynote paper will focus on the available manufacturing processes and review their capabilities to generate multiscale structured surfaces. To compare such processes, the so-called “multiscality” is defined that characterizes the structured surfaces according to the lateral and vertical extent of the individual stacked elements and is used as a first indicator to assess the difficulty of their manufacture. As the boundaries of what is considered a multiscale structure are diffuse, ranges of low, medium and high multiscality are defined instead. After presenting the state of the art of manufacturing processes currently utilized for the manufacture of (not only multiscale) structured surfaces, this keynote paper summarizes the capabilities of single-step and multi-step/multi-physics approaches for their applicability across different scales and gives an outlook on which processes could potentially become relevant in the future.

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.

Forming is widely used due to its high efficiency in material utilization and its high production rate in general. Most forming processes control the geometry of final products through a set of tooling. The increasing demands on lightweight products have challenged the performances and functionalities of tooling. This paper provides a systematic review of recent advancements related to tooling performance and functionalities, including tool materials, tooling fabrication processes (e.g., machining, heat treatment, coating, surface texturing, and additive manufacturing), sensing, and data analytics. Finally, recommendations on future research directions for metal forming tooling are provided.

The hardness, residual stress and other properties of a component's surface layers are crucial to its functionality and durability. To achieve specific improvements to the component's “skin”, engineers need a more detailed understanding of the physical and chemical processes at work during manufacturing processes and how these can be exploited to modify the material properties.

Optimization of machining processes to improve the tribological properties of surface layers has become a subject of industrial development. The modifications caused by manufacturing commonly include changes of topography, hardness or residual stresses. The present study investigates modification of the tribological properties of gear synchronizers by the formation of chemical layers on the metal surface within the final grinding process. These layers similar to phosphate glass emerge from the metalworking fluid additive zinc dialkyldithiophosphate (ZnDTP), which is applied in the process in different concentrations. The layers generated at the surface were measured by time-of-flight secondary ion mass spectrometry (ToF-SIMS). Tribological experiments were conducted on a special synchronizer test facility. ToF-SIMS depth profiling revealed that higher ZnDTP concentrations in the metalworking fluid led to thicker phosphate glass layers on the machined surface. The layer that was generated by the addition of 5 % ZnDTP to the metalworking fluid led to a more homogenous coefficient of friction and a lower amount of wear in the tribological experiments. However, the addition of further ZnDTP, up to a total amount of 10 %, led to higher fluctuations in the coefficient of friction and increasing wear, likely related to the occurrence of friction oscillations resulting from thicker phosphate glass layers. However, the results indicate a good potential for improving surface layer properties of metal workpieces by adjusting the chemical composition of the metalworking fluid applied in the final machining process.

Diamond turning has been proven to be a highly flexible machining process, which is able to effectively fabricate high performance optics. For several years, the machining of diffractive optical elements by Fast Tool Servo assisted diamond turning has been developed further towards the manufacture of holograms (DTH) capable to shape laser beams into designated intensity patterns. In order to further expand the degrees of freedom of this machining process and thus the spectrum of machinable geometries, the structure angle on the workpiece surface can be varied during the cutting process by a rotation of the cutting tool around the y-axis of the machine’s coordinate system. This leads to diffractive freeform surfaces which can be used in optical applications for the modulation of the phase gradient of an incoming wavefront enabling a wavelength-independent light-modulation. The additional twisting tool movement is associated with a variation of the cutting tool engagement as the cross-section of the undeformed chip and the local depth of cut are varying. Therefore load conditions on the diamond tool are changing. For this reason, cutting tests have been conducted on an ultra-precision machine tool, in order to determine the influence of the structure angle on the process forces during cutting of two different cutting materials. The tests have been conducted on ultra-fine grained aluminum as well as German silver. These results are a preparation for setting up process simulations for the prediction of tool failure.

The precision balancing of high speed air-bearing spindles is a delicate process. Due to the low bearing stiffness and the quadratic correlation between angular velocity and centrifugal force, the balancing is usually done manually. In order to prevent damage of the air bearings, multiple iterations for different spindle speeds, up to the working rotational speed have to be conducted, resulting in a time-consuming manual balancing procedure with a loss of accuracy for ultraprecision High Performance Cutting (HPC). In this paper, a novel precision balancing system for automatic balancing of high speed aerostatic spindles based on microfluidic valves is presented. In comparison to manual balancing, the system enables a reduction of balancing time to one third and a rise in balancing accuracy. Due to the remotely controlled microvalves, shifts of the center of mass up to two orders of magnitude more precisely than those achieved with conventional manual balancing operations can be attained.

The concept of Process Signatures is based on the correlation between the internal material loads in manufacturing processes and the resulting material modifications, thus allowing a deeper and more comprehensive understanding of the underlying mechanisms. Traditionally, the studies on machining regarding surface properties and surface integrity aim at finding correlations between machining parameters or process quantities (forces, power etc.) and part’s properties and performance. Different to this traditional approach, Process Signatures focus on the material’s response to machining generated internal material loads. Knowing these physics- and metallurgy-based correlations allows solving the so called inverse problem in manufacturing processes. This means that surface- and sub-surface properties become predictable and can be generated by machine tools in a knowledge-based approach. This keynote paper addresses the state-of-the-art in developing Process Signatures and gives examples on specific Process Signature Components. For two processes - surface grinding with a predominant thermal effect on the workpiece material and deep rolling with a predominant mechanical effect - the Process Signature approach is utilized to solve the "inverse problem".

Für die Fertigung hochfunktioneller optischer Systeme eignet sich vor allem das Diamantdrehen in Kombination mit einem hochfrequenten Piezo-Versteller. Die spezifischen Herausforderungen der Herstellung komplexer Reliefphasenhologramme für die Bilderzeugung auf mehreren Rekonstruktionsebenen sollen beschrieben werden. Die Erzeugung unterschiedlicher Strukturwinkel auf dem Werkstück durch die Rotation der extrem schmalen, rechteckigen Diamantwerkzeuge ist ein Schwerpunkt der Veröffentlichung. The machining of highly functional optical systems is particularly achieved with diamond turning in combination with a high frequency piezo actor. In the paper, the machining process for a complex multi-level holographic structure is described. Especially the challenges of the varying structure angle, generated with the rotation of the rectangular shaped diamond tools, will be addressed.

Diamond Micro Chiseling (DMC) has been established as a machining process for generating miniaturized retroreflective arrays with structure sizes in the micrometer range. This chapter focuses on a comprehensive overview on principles, process performance, and optimizations of DMC for generating micro full-cube retroreflectors on planar surfaces. Furthermore, considerations and initial results for transferring DMC to the machining of curved and freeform surfaces will be shown.