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The concept of Process Signatures allows the reliable and knowledge-based prediction of material modifications (e.g., changes of hardness, residual stress, microstructure and chemical composition) researchers in the field of surface integrity, and manufacturing technologies have already been seeking for a long time. A Process Signature is based on the correlation between the internal material loads in manufacturing processes (e.g., stress, strain, temperature) and the resulting material modifications. The target of this paper is to get a comprehensive view on the development of single Process Signature Components for processes with different predominant impacts. Particularly, a mechanism-based approach leading to significant descriptives of internal material loads for a specific material modification is proposed. By this, a deeper understanding of the underlying mechanisms leading to changes of the workpiece surface layer properties caused by manufacturing processes is provided. The challenging identification of significant mechanisms and descriptives of internal material loads is highlighted for each process, and supporting measurement methods and modeling approaches are presented. Process Signatures are expected to enable the solution of the so-called inverse problem in manufacturing.

The machining of a CaF2lens with the near-perfect crystal structure poses a more challenging task than simply performing a ductile-regime cutting on brittle materials to achieve an optical surface finish without microcracks in the subsurface layer. This research advances the understanding of the ductile–brittle transition mechanism through material characterisation. The convincing evidence for the advantage of ultraprecision diamond turning over the optical polishing process is disclosed in the comparative experimental tests. A promising solution of thermally enhanced microcutting is proposed to meet both the ubiquitous and ad hoc requirements for the fabrication of the CaF2lens. The theoretical foundation for the CaF2microcutting at elevated temperatures is for the first time established based on a semi-quantitative modelling and simulation with the crystal plasticity finite element method.

Temperature fields generated in machining processes affect, among other internal material loads, the material modifications in the workpiece surface layer and therefore influence the functional performance of the final component. In particular this might become critical for multipass machining where the amount of heat in the workpiece is accumulated with every path and layer being cut. In the present work a finite element modelling approach for the milling of a complete steel plate is proposed that minimizes computation time while providing a reasonable accuracy of predicted temperature fields. The milling process is modelled as a moving heat source taking into account material removal. Computation time can be reduced up to 98% by systematically increasing the width of the material removal and the heat source width. The effects of the model reduction regarding the temperature fields are investigated in comparison to a reference simulation and furthermore to experiments.

Surface formation for three-body abrasion is essentially more difficult to model than for two-body abrasion. In contrast to grains embedded in the polishing pad and therefore time-invariant tool geometry for two-body abrasion, here a variable tool geometry is prevailing as a result of the rolling abrasive grains. Nevertheless, three-body abrasion is an important abrasive process in the surface finishing of glass and ceramics and the modelling of the surface formation for mechanical abrasive machining with loose grains is required for a better process understanding and enhanced process design.

Micro milling is a flexible technique for the production of micro mechanical components like dies and moulds and process control is the key to reach the strong production requirements. Requirements, given by engineers and designers, are addressed mainly to the functional performance of the produced part, therfore topographic features are most decisive. Surface parameters, mainly of statistical origin, have been used for a long time in surface characterisation and process monitoring. Furthermore, it is known that these parameters correlate with the desired functional behaviour, but this knowledge is usually not used for a deterministic process design, uneconomic try and error approaches are still common.

This paper presents results for the machining of materials typically applied in ultra precision machining in comparison to a nitrocarburized tool steel. Analyzing and evaluating the machining results regarding surface integrity lead to recommendations for the ultra precision machining of this new mold material. The influence of feed, depth of cut and cutting speed on surface quality, resulting cutting forces and tool wear have been investigated. The results show that the decisive factor for the ultra precision machining of nitrocarburized tool steel are the significantly higher cutting forces. In some cases the high cutting forces lead to vibrations during the turning process deteriorating the surface integrity. Therefore, tool nose radius and depth of cut have to be reduced to minimize the cutting forces and avoid the vibrations.

Aufgrund der immer höheren Anforderungenan die Formgenauigkeit bei optischen Flächen mit komplexen Geometrien (z. B. Freiformflächen für Head-Up-Displays) ist es notwendig, beim deterministischen Polieren auf einer Werkstückfläche lokal vordefinierte Abträge zu erzielen, wodurch eine minimale Formkorrektur bei gleichzeitiger Verringerung der Oberflächenrauheit erreicht wird. Aus diesem Grund bedarf es einer präzisen Steuerung des Polierwerkzeuges. Eine Möglichkeit hierfür ist, das Werkzeug und damit verbundene Materialabträge über Verweilzeiten zu steuern.

Aufgrund der immer höheren Anforderungenan die Formgenauigkeit bei optischen Flächen mit komplexen Geometrien (z. B. Freiformflächen für Head-Up-Displays) ist es notwendig, beim deterministischen Polieren auf einer Werkstückfläche lokal vordefinierte Abträge zu erzielen, wodurch eine minimale Formkorrektur bei gleichzeitiger Verringerung der Oberflächenrauheit erreicht wird. Aus diesem Grund bedarf es einer präzisen Steuerung des Polierwerkzeuges. Eine Möglichkeit hierfür ist, das Werkzeug und damit verbundene Materialabträge über Verweilzeiten zu steuern.

Für die Fertigung komplexer optischer Oberflächen und Mikrostrukturen sind Diamantbearbeitungsverfahren wie das Drehen und Fräsen mit monokristallinen Diamantwerkzeugen fest etabliert. Für spezielle Anwendungen sind diese Fertigungsverfahren allerdings aufgrund ihrer geometrischen und kinematischen Limitierungen nicht immer ohne weiteres einsetzbar [1]. Der folgende Artikel fokussiert auf die Weiterentwicklung eines Konturbohr- und eines Profil-Umfangsfräsverfahrens zur Herstellung von Spritzgussformen für einen strukturierten Ring-Reflektor eines großen neuartigen offenen Operationsleuchten-Systems. Das Ziel des neuen Beleuchtungssystems ist es, eine Ausleuchtung bei hoher Homogenität im Fokusbereich ohne thermische Beeinflussungen und eine hohe Anzahl an Fokuspunkten in der Tiefe zu erreichen. Das System besteht aus einer Gasentladungslampe in Kombination mit einem offenen multi-konvexen Ringreflektor.

High precision molds for the replication of structured optical elements like Fresnel lenses or prism arrays are generated by diamond machining or precision grinding. In some cases surface quality of the replicated components is not sufficient to meet the increasing demands concerning surface roughness and form accuracy for optical applications. Subsequent polishing of the structures may therefore be necessary. Within this work structured molds were finished by a newly developed abrasive polishing process, by laser polishing, and by abrasive flow machining. This paper focuses on the material removal mechanisms and achievable surface quality in abrasive polishing. Surface quality is compared to that achieved by laser polishing and abrasive flow machining.

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