D. Veselovac

Self-optimising Production Systems

One of the central success factors for production in high-wage countries is the solution of the conflict that can be described with the term “planning efficiency”. Planning efficiency describes the relationship between the expenditure of planning and the profit generated by these expenditures. From the viewpoint of a successful business management, the challenge is to dynamically find the optimum between detailed planning and the immediate arrangement of the value stream. Planning-oriented approaches try to model the production system with as many of its characteristics and parameters as possible in order to avoid uncertainties and to allow rational decisions based on these models. The success of a planning-oriented approach depends on the transparency of business and production processes and on the quality of the applied models. Even though planning-oriented approaches are supported by a multitude of systems in industrial practice, an effective realisation is very intricate, so these models with their inherent structures tend to be matched to a current stationary condition of an enterprise. Every change within this enterprise, whether inherently structural or driven by altered input parameters, thus requires continuous updating and adjustment. This process is very cost-intensive and time-consuming; a direct transfer onto other enterprises or even other processes within the same enterprise is often impossible. This is also a result of the fact that planning usually occurs a priori and not in real-time. Therefore it is hard for completely planning-oriented systems to react to spontaneous deviations because the knowledge about those naturally only comes a posteriori.

Intelligent Assembly for Aero Engine Components

In this paper, an intelligent assembly system for a welding process of aero engine components is presented. In contrast to present approaches, the proposed assembly unit is able to automatically align and clamp different rotary components. Furthermore, an optimised orientation of the parts for the adjacent welding process is realised, taking the geometric information of each part into consideration. An optical measurement system is used to orientate the individual components to each other. The controller of the alignment system is implemented by using LabVIEW as a graphical software solution.

Meta-modeling for manufacturing processes

Meta-modeling for manufacturing processes describes a procedure to create reduced numeric surrogates that describe cause-effect relationships between setting parameters as input and product quality variables as output for manufacturing processes. Within this method, expert knowledge, empiric data and physical process models are transformed such that machine readable, reduced models describe the behavior of the process with sufficient precision. Three phases comprising definition, generation of data and creation of the model are suggested and used iteratively to improve the model until a required model quality is reached. In manufacturing systems, such models allow the generation of starting values for setting parameters based on the manufacturing task and the requested product quality. In-process, such reduced models can be used to determine the operating point and to search for alternative setting parameters in order to optimize the objectives of the manufacturing process, the product quality. This opens up the path to self-optimization of manufacturing processes. The method is explained exemplarily at the gas metal arc welding process.

Concept for a Technology Assistance System to Analyze and Evaluate Materials and Tools for Milling

Turbine engine manufacturers permanently aim to improve the efficiency of their products. This is often accompanied by the development of new materials which have to be introduced to manufacturing. As a consequence, engineers responsible for machining process development are regularly confronted with the question, how to identify the optimal machining conditions in order to deal with the new constraints. Nowadays, the effort and success of such identification processes are to a significant degree depending on technology expert skills and experiences. From the process planning perspective, however, this circumstance is characterized by a significant degree of uncertainty.This article presents an innovative concept for a technology assistance system (TAS) for milling. The TAS supports the operator to determine optimal machining conditions by autonomously evaluating machinability criteria such as cutting force, tool wear or surface roughness for certain work piece material/ tool combinations. This includes the planning and organization of milling experiments, its standardized and automated execution as well as the generation of surrogate models to describe the machinability criteria for a given parameter range, serving as input for a future optimization. All functionalities of the TAS are conceptually described and first results achieved using a prototype solution are introduced and discussed.© 2015 ASME

Digitales Technologiewissen durch intelligente Fertigungssysteme

Kurzfassung Ein integraler Bestandteil von innovativen Systemansätzen für die Produktion von morgen ist digitales Technologiewissen. Dieses Wissen kann über Modelle, die prozessspezifische Zusammenhänge mathematisch beschreiben, bereit gestellt werden. Im vorliegenden Artikel wird das grundsätzliche Vorgehen zur Entwicklung solcher Modelle kurz erläutert. Darauf aufbauend wird ein Konzept zur autonomen Wissensgenerierung vorgestellt. Damit wird ein Fertigungssystem befähigt, digitales Technologiewissen selbstständig aufzubauen.

Prozessüberwachung für zertifizierte Fertigungsprozesse in der Luftfahrtindustrie

Kurzfassung Der vorliegende Artikel beleuchtet die aktuelle Situation der Fertigung von sicherheitskritischen Bauteilen in der Triebwerksindustrie. Entscheidend für die Bauteilqualität ist in erster Linie die Oberflächenintegrität. Diese wird in der Produktion derzeit mit Hilfe klassischer nicht-zerstörender Prüfverfahren verifiziert. Neue Ansätze bedienen sich der Prozessüberwachung, die ein großes Potenzial im Bereich der prozessbegleitenden Qualitätssicherung bietet. Ein erster Prototyp für eine industrienahe Lösung zur Prozessüberwachung beim Bohren wird in diesem Artikel vorgestellt.

Increasing Productivity and Process Stability in Turning of Aerospace Materials with High Pressure Lubricoolant Supply

In the field of machining difficult-to-cut materials like titanium or nickel-based alloys, the use of a high-pressure lubricoolant supply may result in a significant increase of productivity and process stability. Due to enhanced cooling and lubrication of the cutting zone and thus reduced thermal tool load, tool wear can be decreased which allows higher applicable cutting speeds. Furthermore, the process stability can be increased as a result of effective chip breaking and chip evacuation. Since energy efficiency is very crucial, pressure and flow rate have to be adjusted carefully and in accordance with the cutting parameters to guarantee best results with less energy. For this purpose, experimental investigations were carried out under variation of the flow rate in order to find the minimum required value for a certain machining task with the overall aim to prevent waste of the media used. To maximize the positive effect of high pressure lubricoolant supply strategy on productivity and process stability, specially designed lubricoolant jet guidance geometry on the rake face was also investigated and compared to conventional turning inserts. To study the effect of high-pressure lubricoolant supply on tool temperature, reference tests also carried out using conventional overflood cooling (CoC). The results suggest that the tool temperature can be significantly decreased compared to CoC by applying the high pressure lubricoolant supply and using specially designed jet guidance geometry in turning the investigated aerospace materials TiAl6V4 and Inconel 718.

Experimental Identification of Cutting Force Coefficients for Finish-Milling Operations Considering the Sensor’s Transmissibility

Due to lightweight construction numerous parts in turbomachinery industry with aerodynamic properties exhibit thin-walled features. Typical examples are compressor blades or turbine blades. Finish-milling depicts a stage of the manufacturing process of these parts with significant value creation. A major limitation of productivity is process stability in terms of self-excited or forced vibration. Different simulation approaches attempt determining a priori the process stability to avoid a bad surface quality, accelerated tool wear, tool breakage or scrapped parts. One distinctive part of these simulations is a cutting force model which incorporates material and tool dependent coefficients. The simulation accuracy directly depends on the exactness of these coefficients. Usually, these coefficients are identified experimentally from cutting force measurements with piezoelectric sensors, whose transmissibility is nonlinear. In this paper a multidimensional stationary inverse filter for compensating the influence of the nonlinear transmissibility of force sensors is presented. In a subsequent step, a Levenberg–Marquardt algorithm is used to identify cutting force coefficients from filtered force measurements. The functionality of the filter is validated by comparing highly nonlinear and almost linear piezoelectric force measurement sensors connected in series during finish-milling experiments. The accuracy of the identified cutting force coefficients is assessed by comparing cutting force simulations to measurements.Copyright

Process Monitoring for Manufacturing of Critical Aero Engine Components: An Overview

Modern production systems stand out due to an increasing degree of capacity utilization of the efficiency available through the production process. As working on a technological threshold as well as on a complex task comes along with an increase of susceptibility to failure, process monitoring is an important means to avoid damage to machines, tools, and component parts and a consequent machine downtime. In order to bring about detection of tool breakage, overload and tool wear, we use different sensor and monitoring systems which are adjusted to the process in the best possible way. This paper gives an overview of existing process monitoring solutions, especially in the field of aero engine manufacturing.© 2014 ASME

Integrative Business and Technology Cases

In order to strengthen the relevance and integrativity of research in the Cluster of Excellence, current best practice “business and technology cases” were selected. Hereby the theories, hypotheses, predictions and technology projects developed in the Cluster of Excellence are evaluated and advanced in close collaboration with leading production companies in Germany and Europe. To make the work more transparent, different application scenarios will be developed.