Assembly Line System Research Articles

An optimal policy for controlling the flow time in an assembly line system

In this paper,an optimal operational strategy is developed to maximize the throughput rate from a finite capacity integrated assembly line system (consisting of a set of tandem workstations, a set of inspection stations, a loading station and an unloading station, linked by a set of transporter stations) while controlling both the bottleneck and the flow time. To develop an optimal operational strategy, a stochastic optimization model is developed and a closed form solution is derived to maximize the throughput rate from the system such that the resulting probability of finding either a workstation or a transporter station blocked is sufficiently close to zero, and the resulting probability of spending time by an arbitrary workpiece either at a workstation or at a transporter station in excess of a desirable value, is sufficiently close to zero.

Operating a flexible assembly line: To control the bottleneck

In this paper, to develop a loading strategy for optimal utilization of a flexible assembly line system while controlling the bottleneck problem, the performance of the system is modeled by a non-Markovian queueing network with finite capacity queueing nodes. A stochastic optimization model is then presented to select the value of the maximum loading rate such that the resulting probability of finding each workstation and each transporter station blocked (e.g., full) is sufficiently close to zero, and a heuristic algorithm is developed to solve the proposed optimization model. Finally an example is presented and the relative accuracy of the proposed algorithm is investigated through a simulation study.

An Operational Strategy for Throughput Maximization and Bottleneck Control in an Assembly Line System: By Selection of the Processing Rates

In this paper, an optimal operational strategy is developed to optimize the system utilization while controlling the bottleneck problem in a finite capacity integrated assembly line system (consisting of a set of tandem workstations, a set of inspection stations, a loading station and an unloading station, linked by a set of transporter stations). To develop the proposed operational strategy, a stochastic optimization model is developed for selecting the optimal processing rates of the workstations and the transporter stations, such that the total throughput rate from the system is maximized while the resulting probability of finding either a workstation or a transporter station blocked is sufficiently close to zero.

An Operational Strategy for Throughput Maximization and Bottleneck Control in an Assembly Line System: by Selection of the Processing Rates

An Operational Strategy for Throughput Maximization and Bottleneck Control in an Assembly Line System: by Selection of the Processing Rates

An Operational Strategy for Throughput Maximization and Bottleneck Control in an Assembly Line System: By Selection of the Processing Rates

An Operational Strategy for Throughput Maximization and Bottleneck Control in an Assembly Line System: By Selection of the Processing Rates

COMPOUND DYNAMIC EVENT METAMODELS FOR ELECTRONIC ASSEMBLY LINE SYSTEMS

In the assembly line systems of the electronics industry, production controls based on steady-state conditions have proved ineffectual in coping with dynamic events, such as machine breakdowns, part supply shortages, and high priority job order processing, which can occur individually or simultaneously. There are few tools that give results quickly as to how many assemblies will be delayed by a dynamic event and how long it will take to recover from the impact. Computer simulation is available, but its lengthy execution time has hindered its application in real time. Previous research discovered that the patterns of these dynamic events can be represented by metamodels in the solution form of first order systems. In this paper, these results are unified and it is further shown that compound dynamic event metamodels can be developed from the individual metamodels using linear additivity. These metamodels are fit to the output from the simulation; and the resulting equations can be used in real time to meas...

Performance modelling of an integrated assembly line system with inspection stations and finite capacity local storages; an approximation algorithm

Abstract To control the bottleneck in a flexible assembly line system consisting of a set of tandem flexible workstations, a set of automated inspection stations, a loading station, and an unloading station, linked by a material handling system, a perturbation (e.g., parametric) approach is presented. The performances of each workstation and each transporter station have been modelled by compatible finite capacity G/M/I queueing systems with generally distributed inter-arrival time, a single Markovian processer, and the first-come-first-served queueing discipline. Finally, an example is presented and the relative accuracy of the proposed approximation algorithm is investigated by a simulation study

Assembly line system dynamic behaviour for high priority job order processing

Very often in a manufacturing plant, an important job order must be processed with higher priority than other regular jobs. It is vital for management to understand the impact on production performance of these high priority job orders. In this paper, this dynamic behaviour of assembly line systems is studied using computer simulation and derived metamodels in the form of mathematical expressions. An extensive computer simulation study is first conducted off-line. Next, analytical representations of the system lmetamodels) are fitted to the dynamic behaviour as simulated. These relatively simple equations can then be used on-line to estimate the impact of high priority job order processing when it occurs. The results indicate that the system response to this dynamic event can be described by first-order exponential delay functions captured in metamodels from simulation results. Using only the metamodels, the finish time of high priority jobs can be predicted and the number of delayed regular assembly products can be estimated in real time in the shop floor. This information is very valuable and useful for production scheduling.

A DESIGN STRATEGY FOR ALLOCATION OF FACILITIES IN AN ASSEMBLY LINE SYSTEM FOR THROUGHPUT MAXIMIZATION AND BOTTLENECK CONTROL

An optimal design strategy is developed to control the bottleneck problem, and for optimal utilization of a finite capacity integrated assembly line system (consisting of a set of tandem workstations, a set of inspection stations, a loading station and an unloading station, lined by a material handling system). To develop the proposed design strategy, a stochastic optimization model is presented to allocate flexible facilities amongst a set of workstations, such that the throughput rate from the system is maximized, while the resulting probability of finding either a workstation or a transporter station blocked will be sufficiently close to zero. The proposed stochastic optimization model is a non-linear channce constrained mixed integer programming model which is transformed into a deterministic mixed integer programming model, and is solved by a branch and bound algorithm.

Minimum Required Local Storages of an Automated Assembly System

An optimal strategy for selection of the required local storages of the workstations and transporter stations of a finite capacity flexible assembly line system is presented while controlling the bottleneck problem. For this purpose, a mixed non-Markovian queueing network with infinite capacity nodes is presented to model its performance, a stochastic optimization model is provided and a heuristic algorithm is developed for solving it. Finally, an example is presented and the approximation results are compared with those from a simulation study.

A knowledge representation method for developing an expert system. Page model.

This paper proposes a knowledge representation method (page model) for developing an expert system. This method has three characteristics : (1) It classifies the knowledge into facts, relation-ships among facts, rules, and an inference mechanism which is a certain arrangement of rules for inference. (2) It notes the features of each knowledge component in one page in such a manner that a theory is usually evolved by using notes. It distinguishes between rules which have a theoretical background and empirical rules for a particular problem. (3) It proposes six symbols to represent the inference mechanism : AND convergence, OR convergence, AND branch, OR branch, backtracking and cut. This model is applied to represent an expert system for a multi-item assembly line, and its advantages are evident.

Estimating simulation metamodel parameters for unexpected shop floor real time events

Abstract In order to better understand assembly line system dynamic behavior and provide a basis for developing effective production controls, three unexpected real time events are studied, including sudden machine breakdown at a work station, parts supply shortage and high priority job order processing. Short term system performance is evaluated by dynamic response variables associated with assembly time and work in process (WIP) inventory. Simulation is used as the modeling tool, and the results are further described by mathematical metamodels for overall system behavior. The system transients can be adequately represented by first order exponential functions, and satisfactory results are also obtained for expressing simultaneous occurrence of dynamic events by combined metamodels using linear additivity. A procedure is proposed for the development of dynamic metamodels. For a given system, only a limited number of simulation runs should be made in advance to estimate the metamodel parameters. Using the resultant application program that only contains the metamodels, whenever an event occurs, without running simulation a user can instantaneously predict the consequence in a specified time period by an estimation to the number of assembly products to be finished late.

Production Planning in Assembly Line Systems

We develop a production planning model in the context of a system of assembly lines or production lines. The model is a large-scale linear program and we provide a polynomial column generation technique for its efficient solution. The column generation technique and the approach therein are also of interest in certain other problems. A numerical example to illustrate the algorithm is included. Finally computational experience with the algorithm is summarized.

Reliability and optimization considerations in a conveyor-paced assembly line system

This paper presents a mathematical model to determine transitional as well as steady state probabilities of various system states in a conveyor-paced assembly line system with the line-conveyor subject to failure and repair. The analysis helps to predict the effect of system parameters on labour efficiency, output rate, and system down time. The on-line service time distribution has been taken as general for wider applicability. An optimization problem for a business concern is then formulated taking into account all the relevant economic implications, and solved for a numercial example by STJMT. The profit function is seen to be a concave function with the cost structure as presented here. The results of the numerical example give convincing evidence that, when the problem is seen in totality, neither worker utilization nor output remain the criteria for optimization.

Micro-electronics Technology and Industrial Relations

Technological change has long been an important characteristic of in dustrial evolution in the Western world. The two most important enabling technologies in the post war period are automation and micro-electronics or chip technology. The first one began in the 1950's and the second in the 1970's, and is now in progress. The chip technology is different from the previous technological innovations in that it can be adopted in practically all sectors of the economy and thereby affect a wide range of activities from production to distribution to consumption. It promises to bring about significant structural changes. For instance, while the conventional mass production or assembly line system, in part because of economies of scale, was suited to large scale enterprises such as Stelco, Dofasco, Firestone, Ford, and General Motors, in industries such as steel, rubber, automobile etc., the chip technology can be employed by small and medium enterprises since it is suited to produce a variety of products in small quantities.

Automobile body assembly line system based on module type robot application

The OKAZAKI plant of the Mitsubishi Motor Corporation started production in August 1977. The plant has adopted the latest layout which could not be developed without the concepts and manufacturing techniques accumulated for many years. Also it is equipped with a highly automated body assembly production line incorporating many industrial robots as one of the major facilities.

An Experimental Assembly Line System for Evaluating Potential Investments

An Experimental Assembly Line System for Evaluating Potential Investments