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    Multi-method analysis of production planning and control for make-to-order companies
    Despite progress in the theoretical understanding of logistic objectives and production planning and control, the actual achievement of objectives in practice is often unsatisfactory. This raises two questions for the scientific community: (1) Why do companies fail to achieve their logistical goals? (2) How can these causes be systematically recorded and analyzed?The idea of the research project is to further develop and combine proven analysis methods in order to answer the outlined research questions. This will make it possible to (1) completely record the actuating, control and target variables of production control, (2) collect reference, planned and actual processes for the tasks of production control, (3) detect deviations between reference, planned and actual processes and (4) check the data quality. In doing so, the analysis will have to cover the complete order fulfillment process from scheduling of quotations to completion of the order.The evaluation is to be carried out step by step together with five partner companies to ensure the applicability and practical relevance of the method.In a follow-up project, the analysis method is to be used to conduct a comprehensive field study on the practice of production planning and control and to build up a publicly accessible, comprehensive database.
      29
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    Logistic Operating Curves for Ship-to-Shore Cranes
    Container terminals are the central hubs of global trade. Smooth container transport operations require efficient and stable logistical processes. The heart of the container terminal is the ship-to-shore crane. This equipment loads and unloads the vessels and therefore handles the containers between the quayside and the vessel. Together with the vehicles for horizontal transport, the so-called terminal trucks, the ship-to-shore crane is the success-critical work system to achieve logistic objectives. It is therefore all the more surprising that the design and control of this system in practice today is often mostly based on empirical values. Up to now, science has relied on a simulation or mathematical optimisation to design and control ship-to-shore cranes and terminal trucks. In practice, these approaches have not yet been able to establish themselves: Simulations require a great deal of technical effort. The mathematically optimised solutions quickly lose their validity due to disruptions and changes in the operational process. So far, there is no procedure that can represent the conflicting goals with manageable effort, sufficient generality and high accuracy and thus enable the design and control of container terminals. The idea of this research project is to transfer the Funnel Model and Logistic Operating Curves Theory to container terminals. These theories have proven themselves in production already and are able to illustrate the conflicting goals in a simple and clear way. Based on this, a procedure for a model-based design and order assignment for container terminals will be developed. The aim is to ensure high productivity of the ship-to-shore cranes and to achieve short dispatch times for the vessels. Both the modelling and the procedures for design and order assignment will be evaluated in a multi-stage process with the help of simulations.
      89  1
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    Schleifen präziser Oberflächen rotierender Leichtbaukomponenten zur Ressourceneffizienz in E-Mobility und Maschinenbau
    Die Fertigung hochpräziser Faserverbundbauteile bildet die Grundlage für nachhaltige und energieeffiziente Antriebskomponenten aus Faser-Kunststoff-Verbund (FKV), die sowohl bei der Herstellung als auch in der Nutzungsphase signifikante Ressourcen- und CO2-Einsparungen ermöglichen. Zentrale Herausforderungen bei FKV-Komponenten sind die Lagerung rotierender Komponenten im Fertigungsprozess, die Ausführung hochpräziser Schnittstellen zu weiteren Antriebskomponenten und sehr enge Bauteiltoleranzen. Ziel des Projekts ist es, die Voraussetzungen für serientaugliche Schleifprozesse hochpräziser Faserverbundbauteile zu schaffen, um die breite industrielle Anwendung von FKV in ressourcenschonenden Antriebskomponenten (Maschinenbau, Automotive, Aviation) zu ermöglichen. Der Fokus des IPMT-Institutes der TU Hamburg liegt dabei auf der Erarbeitung grundlegender Zusammenhänge beim Präzisionsschleifen von FKV abhängig von Werkstück- und Schleifwerkstoff und deren Auswirkungen auf Oberflächenqualität, Maß- und Formtoleranz sowie Ressourceneffizienz. Mit grundlegenden Erkenntnissen der Zerspanbarkeit wird die Basis geschaffen, FKV-Leichtbauteile vielfältiger Geometrien für verschiedene Anwendungen präzise, zielgerichtet, prozesssicher und ressourcenschonend herzustellen. Als Zerspanbarkeitskenngrößen werden Zerspankräfte, -temperaturen, Werkzeugverschleiß, Qualitätsmerkmale sowie Abtragsprodukte zunächst in grundlegenden Umfang-Längs-Plan-Schleifprozessen experimentell untersucht und empirisch modelliert. Auf dieser Basis werden anwendungsgerechte Schleifprozesse entwickelt sowie die Ressourcen- und Energieverbräuche der Schleifprozesse in einer CO2-Bilanz erfasst. Das Projektziel des PKT-Institutes der TU Hamburg ist es, ein vertieftes Verständnis des Reibungs- und Verschleißverhaltens von hochbelasteten FKV-Oberflächen am Beispiel der Hohlschaftkegel-Werkzeugaufnahme (HSK) einer FKV-Werkzeugspindel zu erlangen. Hierfür wird ein anwendungsnaher Tribologieprüfstand entwickelt und in Betrieb genommen. An diesem werden Reib- und Verschleißversuche an gewickelten Testkörpern mit unterschiedlichen Laminaten unter verschiedenen Bedingungen durchgeführt. Hierbei ist insbesondere die Bestimmung von Reib- und Verschleißbeiwerten in Abhängigkeit von Einflussparametern wie Oberflächengüte, Wickelparameter, Schleif-, Kühl- und Schmierverfahren von Interesse, um die Auswirkungen der Schleifprozessgestaltung auf das tribologische Verhalten der Oberflächen zu verstehen. Anhand eines Prüfstandes für HSK-Aufnahmen wird die Übertragbarkeit der Ergebnisse der vorangegangenen, abstrahierten Versuche auf den konkret betrachteten Anwendungsfall nachgewiesen. Auf Grundlage der Untersuchungen werden Gestaltungsempfehlungen für verschleißbelastete Welle-Nabe-Schnittstellen erstellt.
      48  8
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    Betriebskennlinien für Portalkrane - Analyse der Leistungsfähigkeit von Umschlagterminals zur Steuerung der LKW-Ankünfte
    Der Verkehrssektor ist mit rund 20% CO2-Austoß der drittgrößte Verursacher von Treibhausgasemissionen in Deutschland. Ein großer Anteil entfällt dabei auf den Gütertransport mit LKW. Der vielfach aus kleinen und mittleren Unternehmen (KMU) bestehende Kombinierte Verkehr (KV), also die Kombination der Verkehrsträger Straße, Wasserstraße und Schiene, hat das Potential, den CO2-Austoß deutlich zu senken. Allerdings ist der KV heute aufgrund höherer Transportzeiten und ‑kosten oft nicht konkurrenzfähig. Grund hierfür sind maßgeblich die Zeitverluste und Kosten für den Umschlag auf den Terminals. Ein geringer Anteil an Direktumschlägen und zugleich lange und unproduktive Wartezeiten für LKW werden vor allem durch eine unzureichende logistische Planung und Steuerung, insbesondere der Portalkrane als zentrale Arbeitssysteme, verursacht. Ziel des Vorhabens ist es entsprechend, zum einen Durchlaufdiagramme und Betriebskennlinien für Portalkrane als Grundlage für eine modellbasierte Steuerung auf KV‑Terminals zu entwickeln. Zum anderen soll im Vorhaben ein geeignetes System entwickelt werden, um LKW-Ankünfte zu planen und zu steuern. Der Arbeitsplan sieht dazu vor, 1. Referenzprozesse an KV-Terminals aufzunehmen und grundlegende Definitionen von Auftragsarten bzw. Zeitanteilen abzuleiten, 2. Betriebskennlinien und grundlegende Wirkzusammenhänge für KV-Terminals zu modellieren, 3. aus den Modellen ein Vorgehen zur Termin- und Kapazitätsplanung abzuleiten, 4. ein einfaches Monitoring- sowie Auslastungs- und Buchungssystems prototypisch umzusetzen. Dieses System soll auf die vielen KMU des KV zugeschnitten sein und nur vergleichsweise einfache Anforderungen an Datenbedarf, Softwaresysteme und Handhabung stellen. KMU können die Modelle und das Access Management System nutzen, um die Wartezeiten der LKW zu verringern, den Anteil der Direktumschläge zu erhöhen sowie Durchlaufzeit und Zuverlässigkeit der Schiffs- und Zugabfertigung zu verbessern.
      56  11
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    Model-based production planning and control for production areas with sequence-dependent setup times
    With sequence-dependent setup times, companies have to accept high WIP levels and highly scattering throughput times to reach a high output rate. The results of the basic research project provide a model to quantify both the output rate increase by setup cycles and associated throughput time variations as a function of WIP. The aim of the transfer project is to extend the models with important, practically relevant interrelations so they can be transferred to operational production planning and control as well as exemplarily implemented at the industrial partner Robert Bosch GmbH.The main contents of the research project are: (1) Setup cycles influence the required stock in upstream and downstream warehouses, mainly due to the scattering throughput times and their influence on lot sizes. Considering the workstation with setup cycles without taking its influence on stock into account, is an isolated and incomplete perspective. The aim of the research project is therefore to model the influence of setup cycles on stock so companies are able to make informed decisions. (2) In practice, the demand for the setup families is often unevenly distributed. Thus, it makes sense to produce high-volume families more often in the setup cycle than low-volume families. The aim of the research project is therefore to extend the model by considering high- and low-volume families to ensure the practical applicability of the models. (3) Currently, there is no link between the model and the planning approach of companies. Thus, it is difficult to exploit the model’s potential in practice. The aim of the research project is therefore to describe a systematic approach for the definition of relevant planning parameters so that the model’s findings lead to practical improvements. The approach is completed by software tools to calculate the mathematical models and planning parameters. (4) Up to now, there are no documented practical applications of the models so the perceived risk of implementation is very high for companies. The aim of the research project is therefore to implement the models and the planning approach with Robert Bosch GmbH in two pilot areas and to document the findings in a guideline. (5) In practice, there is no general procedure for taking sequence-dependent setup times into account in production planning and control. The aim of the research project is therefore to derive general application tools and to evaluate them in a workshop with three partner companies. Application Partner: Robert Bosch GmbH
      66
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    Investigations on temperature-activated coatings for friction reduction during turning of titanium alloys
    The application of high performance titanium alloys enables great advancement in many sectors of the industry. These materials offer good mechanical, thermal and chemical properties. Application areas of the most widely used titanium alloy TiAl6V4 are in medical technology (implants) in the automotive sector (connecting rods, valves, turbocharger), in the plastic industry (nozzles for injection), in the chemical industry (stirring elements, valves), in power engineering (turbine blades) and in the aerospace industry (engine and suspension parts). The outstanding properties of this material difficult but at the same time its machining. Compared to steel materials, TiAl6V4 exhibits a high temperature resistance up to T = 550 ° C and low thermal conductivity (λ = 5.8 W/mK) as well as a pronounced tendency to strain hardening and an abrasive effect. The poor thermal conductivity leads to high chip temperatures und the process heat flows for the most part in the tools and is not transported through the chip. Another consequence is the development of chemical reactions at the tool surface due to the high process temperature. For the machining of these materials, this means that the tools are subject to a considerable thermal stress and a high mechanical load. Therefore, the production of complex components made of titanium alloys by cutting process is economically not possible due to the fact that this material causes high tool wear, which is associated with high costs. The use of hard coatings deposited by PVD (physical vapour deposition) process for tuning of titanium alloys are not established in the industry. The reason for this is that the corresponding load collective is so far insufficiently researched and the chemical and physical cause-effect relations between titanium and coated tools are not yet understood. The aim of this cooperation research project between IOT and IPMT is the production of temperature active (Cr,Al,V)N coating systems by a combination of dcMS (direct current magnetron sputtering) and HPPMS (high power pulsed magnetron sputtering) technology as well as the investigation of physical and chemical cause-effect relations between coatings and TiAl6V4 and the description of the thermal and mechanical loads during turning of titanium alloy with coated cemented carbide tools. The results of this research project will contribute to make an economical cutting process for titanium alloys possible.
      64
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    Process-independent force and surface model for oblique cutting of fiber reinforced polymers
    Fiber reinforced polymers are often used in lightweight design. Due to the orthotropic material properties, the cutting mechanisms during chip removal differ significantly from those of isotropic materials. So far, the fundamental mechanisms have been investigated primarily for orthogonal cutting. However, oblique cutting is generally present in industrial practice, in which a three-dimensional cutting process occurs due to the spatial engagement conditions of the tool’s cutting edges. The spatial engagement conditions result from a combination of the 3D spatial orientation of the cutting edge and the cutting direction with respect to the fiber.Preliminary studies reveal a significant influence of the 3D spatial cutter-fiber-orientation on the cutting forces and the resulting cutting surface. The surface integrity can affect the mechanical behavior of lightweight structures under static and dynamic loads. In particular, occurring fiber pull-out is critical for the surface integrity. The objective of the project is a cutting force and surface model for the machining of fiber reinforced polymers with particular consideration of oblique cutting. The prediction of cutting forces is based on a semi-empirical model, which has a process-independent validity. The model will be transferred to milling. Furthermore a transfer to drilling out and countersinking is envisaged in a second project phase. Innovative experimental setups enable efficient and comprehensive identification of cutting force coefficients for the first time, also under high cutting speed as well as arbitrary orientation of the cutter and cutting direction relative to the fiber. The surface model is developed from the correlation between the spatial load situation and the measured surface condition. It allows the prediction of critical cutting conditions with respect to surface quality, in particular fiber pull-out. The rotation-angle-dependent simulation of the process forces and the cutting surfaces allows conclusions to be drawn about the process-specific mechanisms in terms of 3D spatial engagement conditions, which has not been possible up to now because of the focus on orthogonal cutting. Compared to the mere mechanistic force modelling by calibration in a drilling or milling process, the semi-empirical model shows the load distribution along the cutting edge. This enables the analysis of phenomena which are only affecting a small region of the cutter and shows optimization potential in terms of surface quality.
      49
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    Machining-induced temperature field in CFRP materials (TFC)
    Due to their remarkable specific strength and stiffness, carbon fiber reinforced plastics (CFRP) are increasingly used for highly loaded lightweight structures, e.g. in the aerospace industry. By suitable arrangement of unidirectional (UD) fiber layers, the fibers can be optimally adapted to the effective load directions. After the original near-net forming process, it is usually necessary to machine the components to meet the precision requirements. Often, milling is used for this step. Workpiece loads associated with machining carry the risk of damaging the functional surfaces mechanically and thermally which may lead to high costs due to repair or scrap.The heat generated during machining, its distribution within the part and the resulting thermal damage are, amongst other factors, dependent on the fiber orientation with respect to the feed direction. In preliminary research, an analytical model for the calculation of the temperature field within orthotropic workpieces for arbitrary fiber orientations was developed. In this model, the (effective) heat source width and the heat flux are of primary importance. Currently, those parameters are difficult to assess, but could be identified for exemplary individual cases from experiments in this research.The objective of this research proposal is to fundamentally investigate the dependence of the thermal process parameters heat source width and heat flux on tool and material properties as well as on the cutting conditions. For this purpose, the existing machining center for cutting of CFRP is enhanced with the necessary measuring equipment for thermomechanical process characterization. Based on experimentally identified features, empirical correlations are deduced and described by a comprehensive model. Thus, the model-based simulation of the temperature field and thermal damage in the heat-affected zone of UD-CFRP workpieces is established as a function of the relevant input parameters.The model established for UD-CFRP is empirically expanded within this project and thereby delivers scientifically relevant findings on cause-effect relationships of thermal damages in machining. It is expected to be of high value for industrial practice, as the model-based simulation of UD-CFRP systems reveals process limits when machining CFRP made of non-crimped fabrics (NCF). The portability to NCF-CFRP as well as the implementation of neglected effects, e.g. the heat transfer at the part surface, will be further investigated in the second funding phase.
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