Stand und Entwicklungstendenzen der Feinschneidtechnik

The State‐of‐the‐art in Fineblanking The State‐of‐the‐art in Fineblanking enables the process‐reliable and economic production of three‐dimensional multifunction‐parts. The combination of Fineblanking with other Cold‐forming operations – beyond semi‐piercings or weld nipples – are leading continuously to new applications. The motivation for such creative solutions is the permanent cost‐down pressure of the parts.     

Eine auf der Systemanalyse von Reibungs- und Verschleißvorgängen aufbauende Methodik zur Auswahl von tribotechnischen Werkstoffen

A method for the selection of tribotechnical materials based on a system analysis of friction and wear processes . The tribological behaviour of materials cannot be specified by their physical, chemical and mechanical properties only. Besides these ?system-independant”? properties ?system-dependant”? data are important. This is demonstrated by applying the methods of systems analysis to friction and wear processes. Based on systems thicking a method for the selection of tribotechnical materials is outlined.     

Plasmalichtquellen – Stand und Ausblick

Plasma Light Sources – Presence and Future Plasma light sources can at present fulfill all demands of general lighting with high efficiency. A further increase of the luminous efficacy and a high flexibility concerning the color temperature with simultaneous substitution of mercury as a filling substance – these are possible options. Solid‐state light sources will only start after some years to seriously compete with certain groups of plasma lamps     

Verschleiß – eine Systemeigenschaft Auswirkungen auf die Verschleißprüfung

Wear — a System Property. Consequences on Wear Testing . Wear research, wear testing and wear reduction are based on the principle that wear is a property of a system consisting of structural and loading parameters. Wear characteristics can therefore only be determined with reference to the system, and wear test methods must be modelled on the practical system considered. Wear systems are investigated by means of laboratory tests on testpieces, components and complete assemblies as well as service tests. Despite their drawbacks, test-piece and component tests under particular conditions are valuable in the development of practical wear systems. As an example, a device for testing test-pieces and components is described. Sliding wear processes are simulated under mixed and boundary friction conditions. Static and dynamic wear conditions can be simulated.     

Verschleiß und Verschleißprüfung

Wear and wear Testing. The following six different wear mechanisms are briefly discussed: adhesive wear, abrasive wear, fatique wear, mechano-chemical wear and thermal wear. As to wear testing it is concluded that for obtaining a priori information on materials, laboratory testing can be quite useful, provided that the environmental conditions that prevail in practice are successfully reproduced in the laboratory. Further, it is always advisable to include in a test programme some reference materials on which practical information is available.     

Vakuumbeschichtung – Heutiger Stand und zukünftige Trends

Thin films have changed the world. Many products of our modern life, like powerful PC's, the Compact Disc, or energy-saving architectural glazings would not exist without vacuum coating technology. During the past 20 years PVD and PECVD processes for deposition of thin films have spread into a huge variety of different applications. Besides microelectronics, the major fields for the near future are flat panel displays, data storage, optics/glass and surface protection. The article outlines today's market situation and tries to characterize present status and future trends in vacuum coating technology on the basis of some selected examples.     

Mauerwerksbefestigungen für zweischalige Fassaden – Stand der Technik

Double‐leaf masonry façades are becoming very popular due to their outstanding thermal and sound insulation properties, their durability and their ability to maintain the climate within a building (see Figure 1). Proper fastening of the facing shell is crucial if these benefits are to be effectively exploited in the long‐term and if building owners are to be given high investment security. The following article provides detailed information and explanations on product solutions that are both technically sound and cost‐effective.     

Verschleiß und Verschleißschutz beim Spritzgießen

Wear and Wear Protection for Injection Moulding Increased power installations at injection moulding machines for higher polymer output rates require improved wear protection measures since the so called ?standard steels”? cannot cope with these demands. This publication describes the adhesive, abrasive and corrosive wear phenomena which are taking place in plasticating units of injection moulding machines as well as the causing factors and resulting effects by means of examples. The influence of different polymers and additives on the service life of the machinery components is also being considered. Finally the article presents solutions to achieve an effective reduction of wear by processing and design related measures, suitable metal surface treatment and adequate material selection for the plasticating unit.     

Verschleißprüfung und Verschleißverhalten von Hartmetallen

Wear testing and wear behaviour of cemented carbides Wear resistance is not a mater constant but a quantity of a system. For the judgement of a case of wear or for the choice of the suitable grade of cemented carbide it is necessary to investigate exactly the limiting conditions and the appearance of wear. The wear test can only be considered with exactly defined limiting conditions and only be compared with application of similar limiting conditions.     

Sekundärneutralteilchen-Massenspektrometrie SNMS – derzeitiger Stand und weitere Entwicklungen

Secondary neutral mass spectrometry (SNMS) based on electron gas postionization is described with regard to its historical developments, its fundamental properties and figures of merit. The quantifiability of SNMS signals, the low detection limits and the excellent depth resolution are shown to be the outstanding potentialities of SNMS. Recent and ongoing instrumental developments are described. In particular, the novel high frequency mode HFM of SNMS allows the analysis of completely or partially insulating samples in almost the same way as the conventional direct bombardment mode for conducting materials. A new generation of SNMS instruments is designed such that X-ray induced Photo Electron Spectroscopy XPS can be incorporated in situ as an option.     

Ermüdungslebensdauerbewertung von Warmumformwerkzeugen – Ein Überblick über den Stand der Forschung und Anwendung

Hot work tools are subjected to complex thermal and mechanical loads during hot forming processes. Locally, the stresses can exceed the material's yield strength in highly loaded areas. During mass production, this leads to cyclic plastic deformations and thermomechanical fatigue of the tools, which can be a major lifetime limiting factor. However, established concepts for thermomechanical fatigue life assessment of hot work tools do not exist, since this aspect first reached attention in the last years with the needs for higher resource and energy efficiency as well as optimized manufacturing processes (e. g. in the frame of Industrie 4.0). Hence, in this paper, the contemporary industrially used concepts for dimensioning hot forming tools regarding the tooling fatigue life are presented. Furthermore an overview of existing plasticity and lifetime models is given. The models are divided in phenomenological and mechanism based models. The review shows that further research is essential in this field.     

Entwicklungsmöglichkeiten und Entwicklungstendenzen auf dem Gebiet der Hochtemperatur-Legierungen

Possible Trends and Developments in the Field of High Temperature Alloys. The continuing development of super-alloys that has for some 25 years allowed a steady increase in the operating-temperature of gas turbines is now closely approaching the limit set by the ultimate operating temperatures of the materials themselves. In order to increase these limits and thus ensure continued progress in this direction new alloys and new processes need to be developed. Possible means for the improvement of conventional super-alloys have been suggested such as:

• new powder metallurgical processes
• production of cast/forged thin section blades by the “Squeeze-Casting”-process
• increasing the ductility of cast alloys by modifying the morphology of primary precipitates in the casting
• increasing the working temperature by means of precipitates having increased dissolution temperatures.

In connexion with this subject, the process of directional solidification, developed during the past 10 years, is briefly discussed with particular reference to its application in the production of columnar and single-crystal super-alloys and eutectic composite materials. The properties of directionally solidified super-alloys as well as directionally solidified eutectic composite materials are summarised in the light of present day knowledge.     

Werkstoffzuverlässigkeit in der Tribologie

The Reliability of Materials in Tribology. The reliability of materials is, in general, reduced by lack of knowledge or the disregard of reaction mechanisms, by the disturbance of chemical or physical conditions of equilibrium and by changes in systems (e. g. combinations of materials, manufacturing processes, interaction with the environment etc.) entailing serious consequences. In the field of tribology, the following examples may be encountered:

• – Reaction mechanisms: Irreversible single threshold value: Transition from a metastable to a stable system; Crystallisation of synthetic materials; Abrasion phenomena with coating layers. Reversible threshold value: Volume change due to changes in physical state; Reversible structural transition. Irreversible cumulative threshold value: Influence of light on the resinification of lubricants; Crack development in the case of fatigue failures; Structurally unstable surface layers; Structural ageing phenomena.
• – Equilibrium: Wear/repolishing equilibrium; Tribological equilibrium of the surface structure; Compatibility of bearing materials; Consumption of additives in lubricating oil; Tribology and corrosion.
• – Interactions and system changes: General influence of basic materials; Interactions and catalysis; Evaporation of synthetic materials; Cleaning systems; Vibration.

     

Reibung und Verschleiß von Polymer-Verbundwerkstoffen

Friction and Wear of Polymer Composites Polymer composites are more and more used as structural components which are very often subjected to friction and wear loadings under use. This paper describes the principle microstructure in polymer composites and their friction and wear properties as a function of microstructural composition. Special attention is focussed on the behavior of these materials under sliding situations against steel and under severe abrasive loading (wear by rough abrasive paper). Models to describe the tribological properties of composites by modified rules of mixtures and/or by terms combining mechanical and microstructural parameters of the partners in contact are introduced.