Showing papers by "Malte Fliedner published in 2007"

Produktionsplanung bei Variantenfließfertigung: Planungshierarchie und Elemente einer Hierarchischen Planung

Abstract: Die Produktionsform der Variantenfliesfertigung hat aufgrund ihrer Anwendungsgebiete in der Endmontage der Automobil-und Elektroindustrie eine grose Bedeutung in der Praxis. Bisherige Forschungsarbeiten beschranken sich zumeist auf ausgewahlte Partialprobleme. Dieser Aufsatz beschreibt die komplette Planungshierarchie der Produktionsplanung bei Variantenfliesfertigung bestehend aus: Erstinstallation der Flieslinie, Produktionsprogrammplanung, Rekonfiguration des Fliessystems, Reihenfolgeplanung und Resequencing. Nach der Beschreibung des Inhalts dieser einzelnen Planungsaufgaben werden diese durch geeignete Kopplungsfunktionen zu einem Hierarchischen Planungssystem verknupft.

Level-Scheduling bei Variantenfließfertigung: Klassifikation, Literaturüberblick und Modellkritik

Abstract: Viele Hersteller von Verbrauchsgutern sehen sich heutzutage einer enormen Variantenvielfalt gegenuber, die sie auf ihren Fliessystemen produzieren mussen. So bietet etwa BMW seine Automobile in 1032 theoretisch moglichen Varianten an. Um nicht die marktseitigen Vorteile dieser Variantenvielfalt durch ineffiziente Produktionsablaufe aufzuzehren, muss die Produktionsplanung diesem Phanomen angemessen Rechnung tragen. Ein wichtiges Aufgabengebiet ist in diesem Zusammenhang die Reihenfolgeplanung, die uber die Fertigungsfolge der Varianten auf einem Fliessystem entscheidet. Im Zuge des ,,Toyota Production System“ hat sich dazu das sog. Level-Scheduling etabliert, welches darauf zielt, den durch die Fertigungsfolge der Varianten induzierten Materialbedarf moglichst gleichmasig auf den Planungshorizont zu verteilen, um so eine Just-in-Time-Versorgung der Linie ohne grosere Lagerbestande zu ermoglichen. Dieser Aufsatz referiert und klassifiziert die zahlreichen Veroffentlichungen zum Level-Scheduling und will vor allem deren Eignung fur den Praxiseinsatz kritisch hinterfragen.

Sequencing mixed-model assembly lines: Survey, classification and model critique

Abstract: Manufacturers in a wide range of industries nowadays face the challenge of providing a rich product variety at a very low cost. This typically requires the implementation of cost efficient, flexible production systems. Often, so called mixed-model assembly lines are employed, where setup operations are reduced to such an extent that various models of a common base product can be manufactured in intermixed sequences. However, the observed diversity of mixed-model lines makes a thorough sequence planning essential for exploiting the benefits of assembly line production. This paper reviews and discusses the three major planning approaches presented in the literature, mixed-model sequencing, car sequencing and level scheduling, and provides a hierarchical classification scheme to systematically record the academic efforts in each field and to deduce future research issues.

The Product Rate Variation Problem and its Relevance in Real World Mixed-Model Assembly Lines

Abstract: Production processes in a wide range of industries rely on modern mixed-model assembly systems, which allow an efficient manufacture of various models of a common base product on the same assembly line. In order to facilitate a just-in-time supply of materials, the literature proposes various sequencing problems under the term "level scheduling", which all aim at evenly smoothing the part consumption induced by the production sequence over time. Among these approaches, the popular Product Rate Variation (PRV) problem is considered to be an appropriate approximate model, if either (i) all products require approximately the same number and mix of parts or (ii) part usages of all products are (almost completely) distinct. These statements are (iii) further specified by analytical findings, which prove the equivalence of product and material oriented level scheduling under certain conditions. These three prerequisites commonly cited in the literature when justifying the practical relevance of the PRV are evaluated by means of simple computational experiments and are then discussed with regard to their relevance in practical settings. It is concluded that the PRV is in fact inappropriate for use in today's real-world mixed-model assembly systems.

Sequencing Mixed-Model Assembly Lines to Minimize Part Inventory Cost

Abstract: A mixed-model assembly line enables the joint production of dierent models of a common base product in intermixed model sequence (lot size one). Previous approaches for the short-term planning task of model sequencing either aim at minimizing work overload (mixed-model sequencing and car sequencing) or leveling part usages (level scheduling). However, at many manufacturers parts are consolidated by a third party logistics provider, who stocks Just-in-Time delivered parts in a consignment warehouse adjacent to the line. The manufacturer issues a complete cargo carrier (e.g. a euro-pallet) whenever his own intermediate storage of parts is depleted. Thus, the manufacturer aims at a model sequence which minimizes his own inventory costs. This paper formalizes this novel model sequencing problem and describes dierent heuristic and exact procedures. Furthermore, the solutions yielded by these approaches are compared to the traditional level scheduling.

Production Planning of Mixed-Model Assembly Lines: Overview and Extensions

Abstract: Mixed-model assembly lines are of great practical relevance and are widely used in a range of industries, such as the final assembly of the automotive and electronics industries. Prior research mainly selected and discussed isolated problems rather than considering the whole planning process. In this article mixed-model production planning is decomposed into five steps: initial configuration of the line, master scheduling, reconfiguration planning, sequencing and resequencing. The paper reviews and discusses all relevant planning steps and proposes general planning instruments as well as formalized decision models for those steps, which have not been thoroughly investigated in the literature thus far.