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In this paper, a new control scheme is proposed for Phase-II monitoring of simple linear profiles in multistage processes. In this scheme, an approach based on the U transformation is first applied to remove the effect of the cascade property involved in multistage processes. Then, a single max-EWMA-3 control statistic is derived based on the adjusted parameter estimates for simultaneous monitoring of all the parameters of a simple linear profile in each stage. Not only is the proposed scheme able to detect both increasing and decreasing shifts but it also has the feature of identifying the out-of-control parameter responsible for the source of process shift. Using extensive simulation experiments, the performance of the proposed method is evaluated and is compared with the ones of some other available methods for both weak and strong autocorrelations. Moreover, the diagnostic performance of the proposed method is evaluated. The results show that the proposed scheme performs well and works better than the competing methods. The application of the proposed method is illustrated at the end using a numerical example. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Since testing wide range of management decision in real-world production is absolutely impossible, discrete-event simulation has often been adopted to evaluate the manufacturing system performance. Performance of various layout alternatives can be studied using simulation. In this paper there are presented reasons to use simulation in order to evaluate manufacturing system performance. Paper presents a simulation approach to assessing the impact of management decision on a production process and the associated impact on costs and on potential gain. [ABSTRACT FROM AUTHOR]

The characteristic of layered manufacturing is the incremental build-up which inevitably leads to the staircase effect. One method to reduce this effect is to optimise part orientation and to apply adaptive slicing procedures. Although layer thickness will be decreased in some regions, process efficiency can be kept to a reasonable level. This paper presents different approaches of adaptive slicing for laser-based applications in consideration of limited range of thickness variation to ensure the mechanical part properties. In contradiction to previous work, the number of applied layer thicknesses is limited due to the associated process parameters. In order to optimise the slicing process and to obtain the best results, this paper presents a practicable approach based on existing work to simulate adaptive slicing. To underline the potential of non-uniform slicing, illustrative examples will show possible improvements in the case of replacing the uniform slicing procedure. [ABSTRACT FROM AUTHOR]

The role of flexibility in manufacturing is becoming most important as the pressures due to variety of products are continuously increasing coupled with declining volumes and faster response to customers. This paper deals with implementation of manufacturing flexibility at the shop floor level of the industry under consideration. The main objective of this paper is to compare the performance of existing manufacturing system with that of flexibility based manufacturing system. To achieve the objectives simple demo simulation model of the existing and proposed manufacturing system is built and performance compared. Both these system are compared on the following performance measures i.e., total production and total production time. The introduction of flexibility causes a decrease in makespan time, with maximum reduction in the makespan time occurring when routing flexibility is increased from 0 to 1. Also total production of parts increases with the increase in the level of flexibility. [ABSTRACT FROM AUTHOR]

Over the past quarter century, much effort has been devoted to the design and development of simulation modeling languages, and to methods for the development of simulation models themselves. Less effort, however, has been expended on the design of the experimental models upon which simulation studies are based. This paper describes a methodology for the determination of near optimal solutions considering experimental design and simulation modeling. Using this methodology, simulation scenarios are created and analyzed using an analysis of variance (ANOVA)-based experimental design. This paper also presents an application of this method in analyzing a manufacturing system design problem. [ABSTRACT FROM AUTHOR]

Discrete event simulation (DES) has been widely applied to modelling and simulation of computer and engineering systems and is an active field of research that has now evolved from 2D to 3D discrete event simulation. This paper attempts to address several key issues in a successful implementation of DES models based on our own and the previous experiences of others. It describes the common basis, which forms the core for the application of modelling and simulation methodologies that are available to support manufacturing systems analysis, design and performance evaluation. Through a comprehensive literature survey, this paper summarises and compares the most widely used optimisation techniques for simulation of manufacturing systems; an overview of the recent and popular simulation languages and packages available for the modelling and simulation community and the classification of their utility for modelling and simulation of manufacturing systems is also given. Finally, this paper summarises and reports the latest development in the most exciting world wide web (www)-based simulation techniques that represent a future that may completely change the nature and future exploitation of modelling and simulation technology in industry. [ABSTRACT FROM AUTHOR]

A manufactured home is completely built in a controlled factory environment. Despite a large share of the market, the manufactured housing industry has a long way to go towards streamlining its production process. The objective of this paper is to map the production process of a manufactured housing factory and to demonstrate via simulation how the process can be improved. The production process including assembly, feeder, and storage stations were mapped using data from several manufactured housing plants and in-depth case studies at two plants in northern Indiana. The case study plants were also used for collecting cycle-time data for developing the simulation model for the roofing process. Subsequently, four “what if” scenarios were conducted to illustrate potential improvements to the production process. The efforts presented in this paper are part of on-going research sponsored by the National Science Foundation under the Partnership for Advancement of Technology in Housing (PATH) initiative. [ABSTRACT FROM AUTHOR]

Numerous methodologies have been developed for the plant-wide control (PWC) of industrial processes. These methodologies can be classified into heuristics, optimization, mathematical, and mixed approaches. However, most of these methodologies do not involve the extensive usage of rigorous process simulators as part of the control system development. Also, in recent years, the focus has shifted toward the use of mixed approaches, which builds synergies between different techniques. As part of the continuing search for more effective PWC system design methods, an integrated methodology is proposed in this paper. This eight-level framework incorporates heuristics and optimization, together with the use of simulation throughout the procedure. The main intuitive feature of this framework is the identification of key controlled variables for optimal operation; this is achieved by detailed analysis of disturbances, computation of the new optimal set points by reoptimization, and cost breakdown analysis for throughput changes. Another important feature is the use of dynamic performance measures to aid in analyzing the effects of integration. This framework is then applied to the styrene monomer plant case study presented earlier [Vasudevan et al. Ind. Eng. Chem. Res.2009, 48, 10941–10961] to develop a viable control structure. The performance of the resulting control system is compared with the control system developed using the integrated framework of simulation and heuristics. While both the control structures are found to be stable and robust in the face of disturbances, the control structure developed in the present work performs significantly better, in terms of steady-state profit and the dynamic economic index based on deviation from the production target. [ABSTRACT FROM AUTHOR]

The operation of complex production processes is one of the most important research and development problems in process engineering. A safety instrumented system (SIS) performs specified functions to achieve or maintain a safe state of the process when unacceptable or dangerous process conditions are detected. A logic solver is required to receive the sensor input signal(s), to make appropriate decisions based on the nature of the signal(s), and to change its outputs according to user-defined logic. The change of the logic solver output(s) results in the final element(s) taking action on the process (e.g., closing a valve) to bring it back to a safe state. Alarm management is a powerful tool to support the operators’ work to control the process in safe operating regions and to detect process malfunctions. Predictive alarm management (PAM) systems should be able not only to detect a dangerous situation early enough, but also to give advice to process operators which safety action (or safety element(s)) must be applied. The aim of this paper is to develop a novel methodology to support the operators how to make necessary adjustments in operating variables at the proper time. The essential of the proposed methodology is the simulation of the effect of safety elements over a prediction horizon. Since different manipulations have different time demand to avoid the evolution of the unsafe situation (safety time), the process operators should know which safety action(s) should be taken at a given time. For this purpose a method for model based predictive stability analysis has been worked out based on Lyapunov’s stability analysis of simulated state trajectories. The proposed algorithm can be applied to explore the stable and unstable operating regimes of a process (set of safe states), information that can be used for PAM. The developed methodology has been applied to two industrial benchmark problems related to the thermal runaway. [ABSTRACT FROM AUTHOR]

This paper proposes a technique for estimating steady-state quantiles from discrete-event simulation models, with particular attention paid to cycle time quantiles of manufacturing systems. The technique is based on the Cornish-Fisher expansion, justified through an extensive empirical study, and is supported with mathematical analysis. It is shown that the technique provides precise and accurate estimates for the most commonly estimated quantiles with minimal data storage and low computational requirements. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we analyze and evaluate the effects of some pre-defined process parameters on the performance of a manufacturing system. These parameters include two different plant layout types, namely functional layout (FL) and cellular manufacturing layout (CL), as well as scheduling rule, machine downtimes, batch sizes, and transporter (interstage transporters) capacities. First we employ simulation to evaluate the effects of these factors on the performance of the system and then conduct designed experiments to set the best levels for these factors. The performance evaluation function is defined in terms of the average flow time of all the part types through the manufacturing system. Arena 10.0 simulation software and SPSS 9.0 statistical package are used to measure the main effects and interactions between these factors. This work demonstrates that various manufacturing parameters should be considered jointly when designing or redesigning a facility because setting different levels for parameters can considerably affect the performance of a facility. [Copyright &y& Elsevier]

The notion of service times is of such fundamental importance in the analysis of queues that it has long been taken for granted. Intuitively, it is used to represent the time interval that a server is capable of completing a dispatched job. However, actual measurements of service times under simple queues in production lines have encountered practical difficulties, in spite of its seemingly deterministic nature. Previous studies have introduced concepts of effective process times to quantify service times. Besides notions of theoretical processing times, raw process times and queueing times, among others, are commonly used in various applications. Their existence causes confusion in the determination of service times and clarification of such terminologies is needed. A simple model is examined to quantify the various concepts and establish their interrelationships. This paper brings out new properties of effective process times with a dynamic dependence on utilization. Discrete event simulations are conducted to verify these properties and explain the phenomenon of indetermination of service times. Both theoretical prediction and simulation results show that unless the system is fully loaded, service time and effective process time are not equivalent and it cannot be measured directly from observations of effective process times. [ABSTRACT FROM AUTHOR]

The introduction of new materials into industrial components can give benefits in terms of cost and performance. It may also allow faster or cheaper production methods. However, in order to maximise the benefits, work must be done to optimise the material for its required role and to configure the process for efficient production.In this paper, the main stages in a streamlined cast one-step forge manufacturing process are modelled. A 3D model is used to optimise the mould design and process parameters. This model can be adapted to cope with variations in material without the need to resort to trial-and-error prototyping. In this case, the use of an A514 alloy with the addition of an in situ formed TiB2 particulate is investigated. Constitutive data for the simulations is derived from a series of lab-scale experiments.The structure and performance relations are established for an automotive component and the combination of material optimisation and simulated processing steps are validated by the pilot scale production and testing of an automotive suspension control arm. [Copyright &y& Elsevier]

Operation flexibility is one of the eight common types of flexibility that exist in flexible manufacturing systems. Dispatching rules are commonly used in loading the machines. This paper studies the effects of different levels of operation flexibility and various dispatching rules on the performance of a flexible manufacturing system. The system performance considered is mean flow time. Simulation results indicate that the mean flow time cannot be always improved by increasing the level of operation flexibility. Altering the dispatching rules seems to have a more significant effect on the mean flow time performance than changing the level of operation flexibility. [ABSTRACT FROM AUTHOR]

A system for geometric and physical simulation of the ball-end milling process using solid modeling is presented in this paper. A commercially available geometric engine is used to represent the cutting edge, cutter and updated part. The ball-end mill cutter modeled in this study is an insert type ball-end mill and the cutting edge is generated by intersecting an inclined plane with the cutter ball nose. The contact face between cutter and updated part is determined from the solid model of the updated part and cutter solid model. To determine cutting edge engagement for each tool rotational step, the intersections between the cutting edge with boundary of the contact face are determined. The engaged portion of the cutting edge for each tool rotational step is divided into small differential oblique cutting edge segments. Friction, shear angles and shear stresses are identified from orthogonal cutting data base available in the open literature. For each tool rotational position, the cutting force components are calculated by summing up the differential cutting forces. The instantaneous dynamic chip thickness is computed by summing up the rigid chip thickness, the tool deflection and the undulations left from the previous tooth, and then the dynamic cutting forces are obtained. For calculating the ploughing forces, Wu's model is extended to the ball-end milling process [21]. The total forces, including the cutting and ploughing forces, are applied to the structural vibratory model of the system and the dynamic deflections at the tool tip are predicted. The developed system is verified experimentally for various up-hill and down-hill angles. [ABSTRACT FROM AUTHOR]

We present a general manufacturing-cell simulation model for evaluating the effects of world-class manufacturing practices on expected cell performance. The modular structure of the simulation provides the flexibility to analyze a wide variety of manufacturing cells. We formulate a comprehensive annualized cost function for evaluation and comparison of alternative cell configurations. A case study involving assembly of printed circuit hoards illustrates the potential benefits of using this tool for cell design and analysis. The simulation model is intended for use in a two-phase approach to cell design that is based on simulated experimentation and response surface analysis as detailed in a companion paper. [ABSTRACT FROM AUTHOR]

We present a two-phase approach to design and analysis of manufacturing cells based on simulated experimentation and response surface methodology using a general manufacturing-cell simulation model. The first phase involves factor-screening simulation experiments to identity design and operational factors that have a significant effect on cell performance as measured by a comprehensive annual cost function. In the second phase of experimentation, we construct simulation (response surface) metamodels to describe the relationship between the significant cell design and operational factors ( the controllable input parameters) and the resulting simulation-based estimate of expected annual cell cost (the output response). We use canonical and ridge analyses of the estimated response surface to estimate the levels of the quantitative input factors that minimize the cell's expected annual cost. We apply this methodology to an assembly cell for printed circuit hoards. Compared to be current cell operating policy. the simulation metamodel-based estimate of the optimum operating policy is predicted to yield average annual savings of approximately $425 000, which is a 20% reduction in annual cost. In a companion paper, we detail the structure and operation of the manufacturing-cell simulation model. [ABSTRACT FROM AUTHOR]

In this paper an analytical approximation for the performance of non-homogenous asynchronous Flow Production Systems (FPSs) with finite buffers is presented. Generally distributed stochastic processing times as well as breakdowns and imperfect production are considered. The procedure explicitly accounts for simultaneous blocking and starving. The approximation is based on the decomposition of an M-station-line into M -- 1 two-station-lines which are analyzed with the help of a GI/G/ I /Nmax queueing model. Numerical comparisons with exact and simulation results for hypothetical as well as for real-life flow-lines indicate that the procedure provides accurate results. [ABSTRACT FROM AUTHOR]