Investigation of chip formation of Ti–6Al–4V in oxygen-free atmosphere

Titanium and titanium alloys have high strength at low density, good corrosion resistance and excellent biocompatibility. Therefore, the use of titanium materials is well established in high-performance applications such as aerospace and biomedical. However, titanium and titanium alloys such as Ti–6Al–4 V have low thermal conductivity, exhibit unfavorable chip formation with typical segmented chips and have high chemical affinity to surrounding elements such as oxygen. Tool wear and the properties of the component surface and sub-surface are significantly influenced by the presence of oxygen and resulting chemical interactions. Among other things, chemical reactions such as oxidation occur due to the high temperatures and presence of oxygen. In this work, the chip formation of Ti–6Al–4 V at different cutting speeds in discontinuous orthogonal cutting process under different atmospheres is investigated. A conventional air atmosphere, a pure argon atmosphere and a silane-doped atmosphere were used. The oxygen content of the silane-doped argon atmosphere corresponds to an extremely high vacuum (XHV), which is practically oxygen-free. It was found that chip formation is affected by the surrounding atmosphere. At the cutting speed vc = 80 m/min, non-periodic segmentation is present under oxygen-free atmosphere, while segmental chip formation occurs under air. This is accompanied by up to 16.5% lower feed force under inert gas atmosphere, which is due to reduced friction caused by the use of an oxygen-free atmosphere

Sandwich rolling of twin-roll cast aluminium-steel clad strips

In the present study experimental results of twin-roll cast aluminium-steel clad strips of a thickness of 2.0 mm using the example of pure aluminium and an austenitic steel are presented. Electron probe measurements of the bonding area revealed the presence of a continuous interface layer of about 2 μm. To verify the formability of the twin-roll cast clad strips, sandwich samples were cold rolled with up to 66% strain. Furthermore, the sandwich samples were hot rolled at the temperature of 300 °C with different strain values. Mechanical properties, the microstructure and the surface quality of the deformed compound after rolling were analysed. To test ductility and formability of the rolled strips these were cold deep drawn.DFG/SCHA1484/21-

Prediction of continuous cooling diagrams for the precision forged tempering steel 50CrMo4 by means of artificial neural networks

Quenching and tempering of precision forged components using their forging heat leads to reduced process energy and shortens the usual process chains. To design such a process, neither the isothermal transformation diagrams (TTT) nor the continuous cooling transformation (CCT) diagrams from literature can be used to predict microstructural transformations during quenching since the latter diagrams are significantly influenced by previous deformations and process-related high austenitising temperatures. For this reason, deformation CCT diagrams for several tempering steels from previous works have been investigated taking into consideration the process conditions of precision forging. Within the scope of the present work, these diagrams are used as input data for predicting microstructural transformations by means of artificial neural networks. Several artificial neural network structures have been examined using the commercial software MATLAB. Predictors have been established with satisfactory capabilities for predicting CCT diagrams for different degrees of deformation within the analyzed range of data.DFG/CRC/48

Towards dry machining of titanium-based alloys : A new approach using an oxygen-free environment

In the current study, the potential of dry machining of the titanium alloy Ti-6Al-4V with uncoated tungsten carbide solid endmills was explored. It is demonstrated that tribo-oxidation is the dominant wear mechanism, which can be suppressed by milling in an extreme high vacuum adequate (XHV) environment. The latter was realized by using a silane-doped argon atmosphere. In the XHV environment, titanium adhesion on the tool was substantially less pronounced as compared to reference machining experiments conducted in air. This goes hand in hand with lower cutting forces in the XHV environment and corresponding changes in chip formation. The underlying mechanisms and the ramifications with respect to application of this approach to dry machining of other metals are discussed. © 2020, MDPI AG. All rights reserved

Towards dry machining of titanium-based alloys: a new approach using an oxygen-free environment

In the current study, the potential of dry machining of the titanium alloy Ti-6Al-4V with uncoated tungsten carbide solid endmills was explored. It is demonstrated that tribo-oxidation is the dominant wear mechanism, which can be suppressed by milling in an extreme high vacuum adequate (XHV) environment. The latter was realized by using a silane-doped argon atmosphere. In the XHV environment, titanium adhesion on the tool was substantially less pronounced as compared to reference machining experiments conducted in air. This goes hand in hand with lower cutting forces in the XHV environment and corresponding changes in chip formation. The underlying mechanisms and the ramifications with respect to application of this approach to dry machining of other metals are discussed

Approach for the monetary evaluation of process innovations in early innovation phases focusing on manufacturing and material costs

In early innovation phases, the monetary evaluation of process innovations is a challenge for companies due to a lack of data. However, an innovation evaluation is essential in an early innovation phase to ensure that process innovations deliver economic value added (EVA) in early innovation phases and to channel technology transfer expenditures in a goal-oriented manner. This paper presents an approach for a semi-quantitative procedure for the monetary evaluation of process innovations in the early innovation phase focusing on manufacturing and material costs. Exemplarily, the approach is applied to process innovations of the Collaborative Research Center 1368 on oxygen-free production. In order to ensure the net present value orientation within the innovation evaluation, the procedure developed is based on a driver tree of the EVA. To link value drivers of the EVA and innovation-driven factors influencing EVA, the EVA driver tree is further systematized with a focus on manufacturing and material costs using a literature-based impact model. Based on the last level of the impact model, a guideline for a semi-structured expert interview is developed. Using this interview guideline, data is collected in the form of innovation-driven influencing factors, which represent the input for the final monetary innovation evaluation. An adapted weighted scoring model is used to draw a semi-quantitative conclusion regarding the EVA achieved by the process innovation. The practical application of the approach developed to process innovations in oxygen-free production has shown that, in the context of three process innovations under consideration, their implementation with the aim of achieving an EVA through reduced manufacturing and material costs at the current innovation status is not effective. However, based on the impact model developed, corresponding levers can be identified to positively influence the EVA and thus also the industrialization of the process innovation. Finally, further necessary steps are identified to evolve the presented approach into a complete method for monetary innovation evaluation in early innovation phases

Effects of Anacetrapib in Patients with Atherosclerotic Vascular Disease

BACKGROUND: Patients with atherosclerotic vascular disease remain at high risk for cardiovascular events despite effective statin-based treatment of low-density lipoprotein (LDL) cholesterol levels. The inhibition of cholesteryl ester transfer protein (CETP) by anacetrapib reduces LDL cholesterol levels and increases high-density lipoprotein (HDL) cholesterol levels. However, trials of other CETP inhibitors have shown neutral or adverse effects on cardiovascular outcomes. METHODS: We conducted a randomized, double-blind, placebo-controlled trial involving 30,449 adults with atherosclerotic vascular disease who were receiving intensive atorvastatin therapy and who had a mean LDL cholesterol level of 61 mg per deciliter (1.58 mmol per liter), a mean non-HDL cholesterol level of 92 mg per deciliter (2.38 mmol per liter), and a mean HDL cholesterol level of 40 mg per deciliter (1.03 mmol per liter). The patients were assigned to receive either 100 mg of anacetrapib once daily (15,225 patients) or matching placebo (15,224 patients). The primary outcome was the first major coronary event, a composite of coronary death, myocardial infarction, or coronary revascularization. RESULTS: During the median follow-up period of 4.1 years, the primary outcome occurred in significantly fewer patients in the anacetrapib group than in the placebo group (1640 of 15,225 patients [10.8%] vs. 1803 of 15,224 patients [11.8%]; rate ratio, 0.91; 95% confidence interval, 0.85 to 0.97; P=0.004). The relative difference in risk was similar across multiple prespecified subgroups. At the trial midpoint, the mean level of HDL cholesterol was higher by 43 mg per deciliter (1.12 mmol per liter) in the anacetrapib group than in the placebo group (a relative difference of 104%), and the mean level of non-HDL cholesterol was lower by 17 mg per deciliter (0.44 mmol per liter), a relative difference of -18%. There were no significant between-group differences in the risk of death, cancer, or other serious adverse events. CONCLUSIONS: Among patients with atherosclerotic vascular disease who were receiving intensive statin therapy, the use of anacetrapib resulted in a lower incidence of major coronary events than the use of placebo. (Funded by Merck and others; Current Controlled Trials number, ISRCTN48678192 ; ClinicalTrials.gov number, NCT01252953 ; and EudraCT number, 2010-023467-18 .)

Total Airport Management - A holistic approach towards airport operations optimisation

Overview over the Total Airport Management (TAM) Concept and the research associated to TAM within the German Aerospace Center (DLR) Institute of Flight Guidanc

CLOU Nutzenbewertung und Validierungsbericht

Validierungsbericht mit Nutzenbewertung zum Planungssystem CLOU, Prototyp Stufe 1

Total Airport Management Concept

High level presentation on the Total Airport Management (TAM) Concept developed by DLR and Eurocontrol. The TAM concept is based on Airport-CDM and relies on a system wide implementation of ACDM to share data between airport stakeholders. TAM takes the idea of information sharing and collaborative decision making into the management of airport operations on a pre-tactical level. In addition it incorporates a holistic approach by taking into account landside and airside information. The future network of TAM airports will lead into system wide improvements in processes and capacities