A methodology for the solution of single-model, stochastic assembly line balancing problem is developed for the objective of minimizing the total labor cost (dictated by the number of stations on the line) and expected incompletion cost arising from tasks not completed within the prespecified cycle time. The proposed procedure is an approximation procedure that divides the problem into subproblems. For each subproblem, an approximate solution is obtained using the dynamic programming procedure developed for the problem. This procedure is incorporated with a special bounding strategy to overcome the rapidly increasing storage and computational requirements as the size of the problem increases. These approximate solutions are further improved by a branch-and-bound type of procedure called the improvement procedure. This procedure uses approximate costs, instead of lower bounds, to fathom the nodes of the enumeration tree constructed; thus, it is not, in the true sense of the word, the branch-and-bound technique. Consequently, the procedure is not guaranteed to result in the optimal solution; however, it is shown to generate solutions within (1 + ε) of the optimal solution. The improvement procedure either improves the approximate solutions obtained using the dynamic programming procedure or determines that they are quite close to the optimal ones. The improved solutions of the subproblems are then appended to each other to produce the solution of the original problem. Some dominance properties that contribute to the effectiveness of the improvement procedure and help in reducing the size of the enumeration tree are developed. Some sequencing and scheduling problems related to the node evaluation scheme of the improvement procedure are also investigated. A single-machine sequencing procedure is developed for the objective of minimizing the expected incompletion cost with tasks having a common due date and stochastic processing times. This procedure is extended to construct a schedule on M parallel machines. In these procedures, in-completion costs of the tasks are independent of their expected performance times; it can be interpreted as relaxing the precedence relations among the tasks. Solution procedures are also developed for the above sequencing and scheduling problems for the case in which the incompletion costs of the tasks are proportional to their expected performance times. Computational results and analyses made indicate that these procedures result in almost optimal solutions. / Ph. D.

This is a bachelor thesis which handles a balancing problem in a manual assembly line for mixed models. Many product variations that are assembled in an assembly line have different cycle times in each operation in the process. The products that are assembled in the line have also large variations in their lead times. This leads to large balancing losses leading to reduced productivity and efficiency. Many balancing losses occur due to the inefficient time that one of the products causes. Other balancing losses occur due to bottlenecks that occur in some operations. The purpose of this study is to investigate the balancing losses in a manual assembly line with mixed models. The goal is to develop a proposal for a balanced layout, as well as to minimize balancing losses and waste and maximize productivity as much as possible. Two research questions have been developed as guidelines for the study: RQ1: What factors can lead to balancing losses in a mixed-model assembly line? RQ2: How can a mixed-model assembly line be balanced without leading to other types of losses? The study is a case study that looks for problems in one case company. It is based on a literature study and the collection of real-world data, which has been collected at the case company by observations, interviews and documents that include data about production times and balancing reports.  A proposal on how balancing losses can be reduced in the best possible way has been developed. The inefficient time has been reduced and the assembly line has become more efficient and productive. With help of this improvement proposal, other types of losses could be avoided, such as losses of human resources and financial resources. This study aimed to reduce the balancing losses that one product causes in the assembly line. No rebalancing of the other products was done, but other products were considered so that the balancing of the product does not lead to extra imbalance on the other products in the line. It was important for the fall company to be able to implement a solution that does not lead to a lot of other losses. Based on the three solutions proposed, this solution was the most suitable for what the company wants. A new layout for the product’s stations has been proposed. With this layout, efficiency will increase, and downtime will decrease, thus increasing productivity. Proposal three shows that it is possible to balance a mixed-model assembly line, by terminating a product and removing it earlier from the assembly line.   Keywords: Line balancing, manual assembly, balancing loss, mixed products, mixed-model assembly / Det här är ett examensarbete på grundnivå, som behandlar ett balanseringsproblem i en manuell monteringslinje för mixade modeller. Det monteras många produktkonfigurationer som har olika cykeltider i varje station i processen. Produkterna som monteras i linan har även stora variationer i deras ledtider. Detta medför stora balanseringsförluster som leder till minskad produktivitet och effektivitet. Många balanseringsförluster uppstår på grund av den ineffektiva tiden som en av produkterna orsakar. Andra balanseringsförluster uppstår på grund av flaskhalsar som förekommer i vissa stationer.  Syftet med denna studie är att undersöka balansringsförlusterna i en manuell monteringslinje med mixade modeller. Målet är att ta fram ett förslag på en balanserad layout, samt att minimera balanseringsförlusterna och slöseri och maximera produktiviteten så mycket som möjligt.   Två forskningsfrågor har tagits fram som riktlinjer för studien: F1: Vilka faktorer kan leda till balanseringsförluster i en mixad-modellmonteringslinje?  F2: Hur kan en mixad-modellmonteringslina balanseras utan att leda till andra typer av förluster? Studien är en fallstudie som undersöker problem hos ett fallföretag. Studien är baserad på en initial litteraturstudie och insamlad data, som har samlats in från fallföretaget via observationer, intervjuer samt dokument med data om produktionstider och balansrapporter.  Ett förslag på hur balanseringsförlusterna kan minskas på bästa möjliga sätt har tagits fram. Den ineffektiva tiden har minskats och monteringslinan har blivit effektivare och produktivare. Med hjälp av det här förbättringsförslaget, kunde andra typer av förluster undvikas, som exempelvis förluster av mänskliga resurser och ekonomiska resurser.   Denna studie är gjord för att minska balanseringsförlusterna som en av produkterna orsakar i monteringslinjen. Ingen ombalansering på de andra produkterna gjordes, men det togs hänsyn till andra produkter så att balanseringen av den produkten inte leder till extra obalans på de andra produkter i linan. Det var viktigt för fallföretaget att kunna implementera en lösning som inte leder till massa andra förluster. Utifrån de tre lösningarna som föreslagits var denna lösning den mest lämplig för vad företaget önskar sig. En ny layout på produktens stationer har tagits fram. Med denna layout kommer effektiviteten att öka och dötiden minska, och därmed ökas produktiviteten. Förslag tre visar sig att det är möjligt att kunna balansera en mixad-modellmonteringslina, genom att avsluta en produkt och ta ut den tidigare ur monteringslinan.   Nyckelord: Line balancing, manuell montering, balanseringsförluster, mixed products, mixed-model assembly line.

published_or_final_version / Industrial Engineering / Master / Master of Science in Engineering

ABSTRACT The aim of industrial production changed from mass production at the beginning of the 20th century. Today, production flexibility determines manufacturing companies' course of action. In this sense, Volvo Group Trucks Operations is interested in meeting customer demand in their assembly lines by adjusting manpower. Thus, this investigation attempts to analyze the effect of manning on the main final assembly line for thirteen-liter heavy-duty diesel engines at Volvo Group Trucks Operations in Skövde by means of discrete-event simulation. This project presents a simulation model that simulates the assembly line. With the purpose of building the model data were required. One the one hand, qualitative data were collected to improve the knowledge in the fields related to the project topic, as well as to solve the lack of information in certain points of the project. On the other hand, simulation model programming requires quantitative data. Once the model was completed, simulation results were obtained through simulation-based optimization. This optimization process tested 50,000 different workforce scenarios to find the most efficient solutions for three different sequences. Among all results, the most interesting one for Volvo is the one which render 80% of today’s throughput with the minimum number of workers. Consequently, as a case study, a bottleneck analysis and worker performance analysis was performed for this scenario. Finally, a flexible and fully functional model that delivers the desired results was developed. These results provide a comparison among different manning scenarios considering throughput as main measurement of the main final assembly line performance. After analyzing the results, system output behavior was revealed. This behavior allows predicting optimal system output for a given number of operators.

Thesis (M.S.)--Massachusetts Institute of Technology, Alfred P. Sloan School of Management, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND DEWEY. / Bibliography: leaves 128-129. / by Bruce William Lamar. / M.S.

Submitted by Lucio Flore Maciel (floremaciel@gmail.com) on 2017-02-15T08:26:10Z No. of bitstreams: 1 Dissertação Lucio Flore Maciel APLICAÇÃO DA SIMULAÇÃO A EVENTOS DISCRETOS NO BALANCEAMENTO DE LINHA DE MONTAGEM.pdf: 1899747 bytes, checksum: ce39bd6323b1cd070d845c8ce1d9a680 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2017-02-21T17:37:52Z (GMT) No. of bitstreams: 1 maciel_lf_me_guara.pdf: 1899747 bytes, checksum: ce39bd6323b1cd070d845c8ce1d9a680 (MD5) / Made available in DSpace on 2017-02-21T17:37:52Z (GMT). No. of bitstreams: 1 maciel_lf_me_guara.pdf: 1899747 bytes, checksum: ce39bd6323b1cd070d845c8ce1d9a680 (MD5) Previous issue date: 2016-04-01 / O objetivo geral da pesquisa foi desenvolver um modelo de simulação a eventos discretos para ser aplicado ao balanceamento de uma linha de montagem de componentes numa empresa do setor automotivo, buscando aumentar a produtividade da linha e utilizando menores quantidades de insumos. Na situação estudada há muitos elementos com comportamento estocástico, que podem influenciar na produtividade da linha, além da diversidade de insumos que abastecem a montagem, o que torna o balanceamento da linha uma tarefa complexa e favorece o uso da Simulação como procedimento de solução. Na modelagem conceitual do problema estudado adotou-se o método IDEF-SIM e para a simulação foi utilizado o software ProModel®. Como resultados tem-se um modelo conceitual e implementado para uma linha de montagem que possibilitou informações interessantes sobre o problema, tais como: juntar funções de dois postos de trabalhos, eliminar excesso de movimentação e eliminar gargalos. / The overall objective of the research was to develop a simulation model discrete event to be applied to balancing an assembly line components in automotive company, seeking to increase line productivity and using lower amounts of inputs. In the situation studied for many elements with stochastic behavior, which may influence the productivity of the line beyond the range of products that supply assembly, which makes the balancing line a complex task and promotes the use of the simulation procedure as a solution. In conceptual modeling of the studied problem adopted the IDEF-SIM method and for the simulation we used the ProModel® software. As results has a conceptual model and implemented for an assembly line that has enabled interesting information about the problem, such as joining functions of two posts jobs, eliminate excess movement and eliminate bottlenecks.

A fascinating feature of bucket brigade assembly lines is that work load on workers is balanced spontaneously as workers follow some simple rules in the assembly process. This self-organizing property significantly reduces the management effort on an assembly line. We generalize this idea in several directions. These include an adapted bucket brigade protocol for complex assembly networks, a generalized model that permits chaotic behavior, and a more detailed model for a flow line in which jobs arrive arbitrarily in time and are introduced into the system at several points on the line.

In this thesis, we define a new problem area for assembly lines. In the literature, there are various studies on assembly line balancing, but none of them consider multi-manned tasks, task to which at least two operators have to be assigned. Two mathematical models and one constraint programming model are developed for both Type-I and Type-II ALB problems. The objective of Type-I problem is to minimize the number of stations whereas the objective of Type-II problem is to minimize the cycle time. In addition to this, valid inequalities are introduced to make models more efficient. Moreover, heuristic algorithms for both types are developed for large-sized problems. All formulations are applied to a real case study and then experimental analysis are conducted for all formulations to see the effects of problem parameters on performance measures. Exact models are compared each other and performance of heuristic algorithms are compared against the lower bounds.

ABSTRACT FLEXIBLE ASSEMBLY LINE DESIGN PROBLEM WITH FIXED NUMBER OF WORKSTATIONS Barut&ccedil / uoglu, Sirin M.S. Department of Industrial Engineering Supervisor: Prof. Dr. Meral Azizoglu July 2009, 70 pages In this thesis, we study a Flexible Assembly Line Design problem. We assume the task times and equipment costs are correlated in the sense that for all tasks the cheaper equipment gives no smaller task time. Given the cycle time and number of workstations we aim to find the assignment of tasks and equipments to the workstations that minimizes the total equipment cost. We study a special case of the problem with identical task times. For the general case, we develop a branch and bound algorithm that uses powerful lower bounds and reduction mechanisms. We test the performance of our branch and bound algorithm on randomly generated test problems. The results of our experiments have revealed that we are able to solve large-sized problem instances in reasonable times.

In this thesis, we consider a Disassembly Line Balancing Problem (DLBP) with fixed number of workstations. We aim to maximize the total value of the recovered parts. We assume that there is a limited supply for the products to be disassembled. Different components can be obtained by disassembling different units of the product. Our aim is to assign the tasks to the workstations of the disassembly line so as to maximize the total value of the recovered parts. We present several upper and one lower bounding procedure. The results of our computational study have revealed the satisfactory behavior of our bounding mechanisms.