A methodology for designing mixed model stochastic assembly line systems and a computer package to implement it for realistic problem sizes were developed. The methodology consists of three major steps: (1) generation of feasible sequences of feeding models into the line, (2) generation of feasible allocations (balances) of work elements to work stations, and (3) generation of combinations of sequences and allocations with the best ordering of elements within stations, calculation of total expected cost for each combination, and selection of the one with the least cost. For generating feasible balances, an exhaustive search procedure with a number of heuristic rules was used to ensure searching the whole feasible region in limited time. A cost model based on labor and incompletion costs is used to calculate the cost of each combination, and a recursive procedure to calculate incompletion probabilities for each element and incorporate them into the cost model was implemented. An example problem, its results, and the computer package listings are included. / Master of Science

Thesis. 1979. Sc.D.--Massachusetts Institute of Technology. Dept. of Mechanical Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Includes bibliographical references. / by Sergio N. Simunović S. / Sc.D.

Digitized by Kansas Correctional Industries

Os objetivos desta pesquisa foram levantar os benefícios auferidos pela aplicação de melhorias na ergonomia dos postos de trabalho e no abastecimento planejado de peças em uma linha de montagem automotiva, bem como identificar e verificar até que ponto pode-se gerar vantagens competitivas na redução do tempo de montagem do veículo, com a aplicação de investimentos tecnológicos em ergonomia na área de manufatura. A metodologia Methods Time Measurement (MTM), foi escolhida para mensurar as diferenças de tempos de processo, e para coleta e identificação de dados. Foram observadas duas linhas de montagem: a primeira denominada de inovadora, construída há três anos com investimentos em soluções ergonômicas, tanto no abastecimento quanto no processo, e outra, tradicional, construída há 20 anos, com poucos investimentos na área. De posse dos dados necessários dos sistemas estudados e com o uso da tecnologia MTM, a pesquisa avalia e propõe meios de mensurar os ganhos com a redução de atividades que não agregam valor ao produto, com o intuito de viabilizar investimentos em ergonomia em postos de trabalho padronizados, manipuladores, instalações mais modernas e até possuir um time de planejamento de processos de produção mais robusto. Neste trabalho, analisa-se também a influência da ergonomia no custo do produto final, qualidade, retrabalhos, afastamentos médicos e absenteísmo entre outros. / The objectives of this research were raise the benefits gained for the application of improvements in the ergonomics of the workstation in the planned supplying of parts in the automotive assembly line. As well as identifying and verifying until the point that can generate competitive advantages in the assembly time reduction of the vehicle, with the application of technological investments in ergonomics in the area of manufacture. The methodology Methods Time Measurement (MTM) was chosen to measure the differences of times of process, and for collection and identification of data. Two assembly lines were observed, the first called innovator, built three years ago with investments in ergonomic solutions, as much in the supplying as in the process, and another traditional one built 20 years ago, with few investments in the area. Using all necessary data of the studied systems and with the use of MTM technology, the research evaluates and recommends ways to measure the profits with the reduction of activities that not add value to the product. With the intention to make possible investments in ergonomics standardized workstation, manipulators, more modern installations and until have a planning process production team more robust. This work, also analyze the medical influence of the ergonomics in the cost of the final product, quality, rework, medical dismissal and absenteeism among others.

The purpose of this research is to develop an approach to minimize makespan for assigning boards to production lines. Because of sequence-dependent setup issue, board assignment and component allocation have to be performed concurrently. An integrated methodology is proposed to obtain a solution of the two problems. The methodology consists of seven phases: PCB grouping, family decomposition, subfamily sequencing, Keep Tool Needed Soonest (KTNS), component setup determination, component allocation, and board assignment. PCB grouping based on component similarity between boards is used to reduce the problem size. Family decomposition is used when total number of feeder slots required by a family exceeds feeder capacity. Subfamily sequencing and Keep Tool Needed Soonest are applied to minimize the number of component setups. Classification of setup components into standard, semi-standard, and custom setup components is performed to reduce the complexity of the component allocation problem. A component allocation algorithm is developed to balance workload across machines. Assigning board families to production lines is performed using a modification of Longest Processing Time (LPT) rule. Assigning entire PCB families to production lines to minimize makespan is difficult to accomplish since the amount of production time for each family is very large compared to that of individual PCB lot. Splitting some subfamilies is allowed as long as this does not increase makespan. The PCB grouping, family decomposition, subfamily sequencing, Keep Tool Needed Soonest (KTNS), and component setup determination procedures are derived from published research results. The component allocation and board assignment are developed in this research, as well as an overall methodology to integrate the entire problem. Data provided by published literature are employed to evaluate performance of the component allocation algorithm and the integrated methodology. To examine the applicability of the methodology, an industrial data is used with the total imbalance due to setup time and placement time of individual PCB and global makespan as the performance measures. Experimentation is conducted with simulated data based on an industry data to investigate impact of threshold value, feeder capacity, and characteristics of data sets on system performance. / Graduation date: 2002

This thesis describes the application of Bayesian networks for monitoring and diagnosis of a multi-stage manufacturing process, specifically a high speed production part at Hewlett Packard. Bayesian network "part models" were designed to represent individual parts in-process. These were combined to form a "process model", which is a Bayesian network model of the entire manufacturing process. An efficient procedure is designed for managing the "process network". Simulated data is used to test the validity of diagnosis made from this method. In addition, a critical analysis of this method is given, including computation speed concerns, accuracy of results, and ease of implementation. Finally, a discussion on future research in the area is given. / Graduation date: 1999

S.B. Gershwin, I.C. Schick. / "October, 1978." Caption title. / Bibliography: leaf 6. / Supported by the National Science Foundation under Grant no. NSF/RANN APR76-12036

This study is focused on two-sided assembly line balancing problems of type-I and type-II. This problem is encountered in production environments where a two-sided assembly line is used to produce physically large products. For type-I problems, there is a specified production target for a fixed time interval and the objective is to reach this production capacity with the minimum assembly line length used. On the other hand, type-II problem focuses on reaching the maximum production level using a fixed assembly line and workforce. Two different mathematical models for each problem type are developed to optimally solve the problems. Since the quality of the solutions by mathematical models decreases for large-sized problems due to time and memory limitations, two heuristic approaches are presented for solving large-sized type-I problem. The validity of all formulations is verified with the small-sized literature problems and the performances of the methods introduced are tested with large-sized literature problems.

This research investigates a metallurgy manufacturer whose products are assembled on fixed position assembly islands. The products of collaborating company are characterized by large-scale with high complexity and mass customization. With such configuration, a product is always set on one location throughout its whole assembly cycle. Assembly materials, machines and operators can be continuity sent to one location to reduce damage or movement cost. To understand the production challenges of a real-life enterprise, this research investigates production procedures of the collaborating enterprise on planning, scheduling, logistics and assembly. The management challenges of assembly method with fixed-position layout are summarized as: (1) High dynamic of material, tools and operator movement. (2) The movement of operators, assembly machines maybe expensive. (3) The requirements of assembly operators are too high to find suitable operators with low cost. The cause of current production problems of the collaborating enterprise are summarized as: (1) lack of appropriate real-time operation data capturing and collection methods (2) current visibility and traceability functions at shop floor is wasteful, time consuming and inaccuracy (3) production data can hardly be synchronized between different production unites, e.g. assembly island buffers and stock areas. Hence RFID technology is applied to solve the problems. The creation of RFID-enable assembly environment is following the AUTOM RFID implementation solutions. The methodology of deployment RFID hardware facilities and the functions of choosing production object to tag RFID tags, finding value-adding points to deploy RFID readers and building networks to integrate the RFID hardware facilities are introduced. Decision support system is developed to connect and transfer information between shop-floor execution and decision. This system guides executions and collects real-time information involved in execution procedures and converts the information as reference for decision makers. This system can also release shop-floor decisions instantly to operators. Four core components including Explorers, Modules, Services and Data repository compose the framework. These four components interrelates to each other to guarantee the smooth shop-floor information transformation. Finally, a case study demonstrates the RFID solution has been successfully deployed in proof-of-concept shop floor of the collaborating enterprise. The decision support system can proper manage the captured real-time information and convert the information into useful reference data for decision makers. As the operation processes of this case is designed strictly following the real-life operation processes, therefore this RFID solution is capable to be applied in real-life shop floor to assist the enterprise operation and management. / published_or_final_version / Industrial and Manufacturing Systems Engineering / Master / Master of Philosophy

published_or_final_version / abstract / toc / Mechanical Engineering / Doctoral / Doctor of Philosophy