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This paper proposes an analytical model for resources assignment in the context of maintenance activities scheduling. It takes into account the human as well as material resources availability constraints. It allows the decision maker to consider not only the preventive maintenance activities but also the potential failures which may occur during the scheduling horizon. Opportunistic maintenance may be considered as an option to improve the occupational rate mainly for maintenance operators. Additional constraints such as the completion time of some specific maintenance activities and the earliest starting works on a given machine may easily be considered in the model. Recall that the main purpose of this paper is to suggest an improved model for resources assignment to be implemented into a planning and scheduling module in CMMS software. The proposed model generates a feasible plan and makes sensitivity analysis possible in order to take into account the material and human resources fluctuations. A nume...

Lot splitting is the practice of splitting a production order into smaller sub-lots that are free to move independently through the manufacturing process. Traceability issues and increased material handling may discourage high levels of lot splitting and thus limit improved flow times and tardiness that are associated with increased lot splitting. In order to enable the shop floor control necessary for high levels of lot splitting, radio frequency identification (RFID) can be used to improve material tracking. This is the first paper to quantitatively analyse the trade-off between improved flow and tardiness metrics versus the undesirable increase in material handling when lot splitting in a job shop. Flexible automated material handling equipment may be necessary with some operating conditions and policies because of a dramatic increase in material movements between work centres. This is also the first paper to quantitatively study the impact of imperfect RFID read reliability on the shop floor. The find...

This paper deals with controlling flexible manufacturing systems (FMS) operating in volatile production environments. Shnits et al. (Shnits, B., Rubinovitz, J., and Sinreich, D., 2004. Multicriteria dynamic scheduling methodology for controlling a flexible manufacturing system. International Journal of Production Research, 42 (17), 3457–3472.) and Shnits and Sinreich (Shnits, B. and Sinreich, D., 2006. Controlling flexible manufacturing systems based on a dynamic selection of an appropriate operational criteria and scheduling policy. International Journal of Flexible Manufacturing Systems, 18 (1), 1–27.) developed a multi-criteria dynamic scheduling mechanism for controlling an FMS that can cope with such environments. An important part of this mechanism functioning, which impinges directly on its performance, is the activation of its decision-making process. This study continues the research presented in the above-mentioned papers and proposes different triggering methods for activating the control syste...

The traditional inventory classification method classifies stock keeping units (SKUs) to three classes based on their annual dollar usage, while in real world problems, other criteria are important as well. In this paper, considering multi-criteria situations, a simple, effective and practical rule-based method is designed and implemented in a real world case, using MATLAB software. The most important characteristic of the proposed method is taking into account the inherent ambiguities that exist in the reasoning process of the system of classification. The methodology and the method proposed here may be easily implemented by inventory managers. The results obtained from the case study in this paper are compared with the analytic hierarchy process (AHP) method. Finally concluding remarks and suggestions for future work are provided.

This paper reports a research carried out to assess the agility level of an organisation using a multi-grade fuzzy approach. Agility refers to the capability of an organisation to respond quickly in accordance with the dynamic demands of the customers. During this research, an agility index measurement model containing 20 criteria incorporated with the multi-grade fuzzy approach was designed. Subsequently, the data gathered from a manufacturing company was substituted in this model and the proposals for enhancing the agility level of this company were derived. The usage of the model contributed in this paper will indicate the actions required to enhance an organisation's agility level. This process will accelerate the absorption of agility characteristics in modern organisations.

International audience; This paper starts from a notice made in semiconductor industry: process control system and especially control charts provide information that can be exploited for correlation analyses during process investigations. In this industry, key and costly investigations are made for improving yield and reducing scraps. Daily, engineering teams are working at manufacturing improvements. Without process data, their work could take much more time and lead to weak improvements. Nevertheless, design of process control systems and in particular control charts lacks from taking into account this remark. As their is no sound application to infer optimal control chart depending on « business parameters » meetings between several engineering teams occurs frequently to find an affordable quantity of controls for each operations. The literature point of view doesn't provide more recommandations to take into account the reuse of data into these costly investigations. The paper investigates this issue over a simplified process model. It translates into the Lorenzen and Vance model this concept. It simulates the design economic of control chart taking into account this new model and infers new optimal SPC set points. An analysis of this new link is made in a context of yield improvement.

This paper has contributed a system to cost a model called total agile design system (TADS). Using TADS helps an organisation to design its products, processes and services to achieve agility by responding to the customers’ dynamic demands. After the description of TADS, a costing system named as TADS-ABC has been introduced in this paper. As the name implies, this system has been designed to cost TADS using activity based costing (ABC) principles. After highlighting the theory, the practical application of TADS-ABC has been illustrated by substituting the relevant data derived from a TADS implementation study. This implementation study was conducted in an electronics switches manufacturing company. After processing using TADS-ABC, the specific costs to be incurred towards TADS activities, agile criteria and evolving products in an agile manner in the above company could be arrived at. The experiences of conducting this research have been used to evolve a roadmap for successfully implementing TADS-ABC in ...

The capture of manufacturing best practice knowledge in product lifecycle management systems has significant potential to improve the quality of design decisions and minimise manufacturing problems during new product development. However, providing a reusable source of manufacturing best practice is difficult due to the complexity of the viewpoint relationships between products and the manufacturing processes and resources used to produce them. This paper discusses how best to organise manufacturing best practice knowledge, the relationships between elements of this knowledge plus their relationship to product information. The paper also explores the application of UML-2 as a system design tool which can model these relationships and hence support the reuse of system design models over time. The paper identifies a set of part family and feature libraries and, most significantly, the relationships between them, as a means of capturing best practice manufacturing knowledge and illustrates how these can be linked to manufacturing resource models and product information. Design for manufacture and machining best practice views are used in the paper to illustrate the concepts developed. An experimental knowledge based system has been developed and results generated using a power transmission shaft example.

In this paper, we study the productivity advantage of a variety of scenarios in a robotic cell by comparing their cycle times. The robotic cell is made up of several machines and a single gripper robot in the centre of the cell, which loads, unloads and moves the parts. Considering deterministic robot travelling, loading and unloading time elements and stochastic part process time element, this paper focuses on examining the scenarios composed of the single part type part sequencing methods and the robot moves in a cell. First, the decrease (increase) virtual robotic cell, in which its machines are virtually arranged in order of processing time regardless of their physical location, is introduced to calculate the cycle time. Second, a flow-graph based model is developed to analyse the cycle times for the scenarios when the part processing time element is stochastic. A robotic cell composed of three machines and a robot in the centre of the cell is used as a base example throughout the paper to illustrate ...

Flexible manufacturing systems (FMSs) have gained consideration due to their ability to produce customised and an increasing variety of products with shorter life cycles. A considerable amount of research has been done on manufacturing flexibility from different angles. There are many different types of manufacturing flexibility being reported in the literature, and routing flexibility is one of them. The paper focuses on the study of routing flexibility in a flexible system of integrated manufacturing (FSIM) from the view of real-time control strategies. However, flexibility incurs cost hence a judicious decision is required for implementing the right level of flexibility under a different operating environment. The paper studies the impact of routing flexibility and control strategies on the performance of FSIM. The application of discrete event simulation and Taguchi's method is applied to study the various factors contributing to FSIM performance and identifies the vital parameters for improving perfo...

Manufacturing strategy is a plan for moving a company from where it is to where it wants to be. Determining the best manufacturing strategy is not easy because of the wide range of choices and constraints a company faces. Manufacturing strategy frameworks or models are helpful because they identify the objects that comprise manufacturing strategy and organise these objects into a structure that enables a company to understand and use the objects to develop strategy. This paper examines a company's international manufacturing network. It identifies and examines six manufacturing strategy objects (generic international strategies, manufacturing networks, network manufacturing outputs, network levers, network capability, and factory types), linkages between objects, and the manufacturing strategy framework that follows from these objects and linkages. Then the paper applies the framework to the manufacturing networks of three companies in the global steel industry: Arcelor (Luxembourg), Mittal (India), and D...

The optimal fixture layout is crucial to product quality assurance in the multi-station sheet metal assembly processes. Poor fixture layout may lead to product variation during the assembly processes. In this paper, a genetic algorithm (GA)-based optimisation approach has been presented for the robust fixture layout design in the multi-station assembly processes. The robust fixture layout is developed to minimise the sensitivity of product variation to fixture errors by selecting the appropriate coordinate locations of pins and slot orientations. In this paper, a modified state space model for variation propagation in the multi-station sheet metal assembly is developed for the first time, which is the mathematical foundation of optimal algorithm. An e-optimal is applied as the robust design criteria. Based on the state space model and design criteria, a genetic algorithm is used to find the optimal fixture layout design. The proposed method can greatly reduce the sensitivity level of product variation. A ...

In this paper, a machine loading problem in a flexible manufacturing system (FMS) is discussed, with bi-criterion objectives of minimising system imbalance and maximising system throughput in the occurrence of technological constraints such as available machining time and tool slots. A mathematical model is used to select machines, assign operations and the required tools in order to minimise the system's imbalance while maximising the throughput. An efficient evolutionary algorithm by hybridising the genetic algorithm (GA) and simulated annealing (SA) algorithm called GASA is proposed in this paper. The performance of the GASA is tested by using 10 sample dataset and the results are compared with the heuristics reported in the literature. The influence of genetic operators on the evolutionary search in GASA is studied and reported. Two machine selection heuristics are proposed and their influence on the quality of the solution is also studied. Extensive computational experiments have been carried out to ...

This paper is an attempt to evaluate the long term risk of stock-out and obsolescence in continuous review inventory systems, typically of slow-moving but very critical items. Inventory decisions depend very much on the goodness of the estimates of the input parameters like the holding, ordering and stock-out costs. It is a well-known fact that stock-out cost is a very difficult parameter to estimate. The lower it is the lower the quality of service will be while the higher it is the higher the inventory cost would be and possibly higher obsolescence rate too. In this paper, we develop a framework to evaluate the risks, in the long term, of stock-out and obsolescence, especially for inventory of critical spares whose demand rate is not high. For this purpose, we propose the use of quasi-stationary distributions for continuous review (r, Q) inventory systems with the condition that the Laplace transforms of functions of interest are rational algebraic functions. We relate the quasi-stationary distribution ...

Decision makers in the manufacturing sector frequently face the problem of assessing a wide range of alternative options, and selecting one based on a set of conflicting criteria. This paper helps to understand and solve this important problem using a multiple criteria decision making method known as Preference Ranking Organisation Method for Enrichment Evaluations (PROMETHEE). The method is improved in the present work by integrating with analytic hierarchy process (AHP) and the fuzzy logic. The method discussed in this paper is very effective for decision making in various real-life situations of the manufacturing environment. Four examples are included to illustrate the method.

While the effect of protective inventory on the performance of simple lines has received considerable attention, the same cannot be said for re-entrant lines. This paper attempts to meet that deficiency. This paper examines two different but related issues. First, the theory of constraints (TOC) evaporating cloud method is employed to show the traditional dilemma of increasing work-in-process (WIP) to fully utilise resources versus decreasing WIP inventory to reduce cycle time. The assumptions and implications of three different management philosophies (traditional, JIT/lean, and TOC) are explored in addressing this dilemma with respect to the use of both protective inventory and protective capacity. Second, given an unbalanced re-entrant line with fixed capacity, simulation is used to explore the effectiveness of using protective inventory by changing the level of WIP on two dependent variables: cycle time and throughput. Two sources of variation are simulated: processing time and breakdowns (machine fai...

This paper is devoted to serial production lines consisting of producing and inspection machines that obey the Bernoulli reliability and Bernoulli quality models. Such production lines are encountered in automotive assembly and painting operations where the downtime is relatively short and the defects are due to uncorrelated random events. For these systems, this paper develops analytical methods for performance analysis, bottleneck identification, and design. In addition, insights into the nature of bottlenecks in such systems are provided, and an empirical rule for placing an inspection machine that maximises the production rate of non-defectives is formulated.

This paper presents the results of ongoing research aimed at developing an integrated computer-aided tolerancing tool. A unified Jacobian–Torsor approach has been developed for deterministic (worst case) computer-aided tolerancing. The paper describes how one can use the same set of interval-based deterministic equations in a statistical context. The nature of the resulting equations lends itself to very fast computations to determine the percentage of rejected assemblies produced given some statistical distribution of the tolerances of their constituent parts. An example application is also presented to illustrate the use of the developed tool.

This paper deals with tolerance allocation driven by an activity-based approach. Its main objective is to rationally give a good indicator of the relevance of tolerance values fixed by designers. Taking into consideration the impacts of tolerance allocation on the manufacturing process and so the production cost, several examples are given to illustrate this concept. Moreover this paper deals with how the geometrical analysis can be carried out in this activity framework, illustrated by several industrial cases. In addition, this paper explains how, coupled with an optimisation algorithm, this method can generate the best compromise between cost and high performance. To illustrate the efficiency of this approach and its realisation, models and user interfaces based on an industrial case are given.

This paper considers a scheduling problem in the manufacturing of anodic electro-etching aluminium foil. To reduce cost and increase efficiency, the manufacturer of aluminium foil usually designs the equipment for electro-etching of aluminium foil into specialised equipment that is dedicated to produce high voltage or medium voltage aluminium foil based on the range the aluminium foil can bear. Nevertheless, high voltage equipment can be used to produce medium voltage aluminium foil with longer processing time, and vice versa. The problem is to schedule jobs on the high and medium voltage equipment, each having several pieces in parallel, with setup times to minimise to the total completion time. In this paper, we propose a three-stage heuristic for this problem and computationally evaluate the performance of the heuristic in comparison to a heuristic for unrelated parallel machines and a branch-and-bound algorithm.

Machine breakdowns have been recognised in flexible manufacturing systems (FMS) as the most undesirable characteristic adversely affecting the overall efficiency. In order to ameliorate product quality and productivity of FMS, it is necessary to analyse, as well as to minimise the effect of breakdowns on the objective measures of various decision problems. This paper addresses the machine loading problem of FMS with a view to maximise the throughput and minimise the system unbalance and makespan. Moreover, insufficient work has been done in the domain of machine loading problem that considers effect of breakdowns. This motivation resulted in a potential model in this paper that minimises the effect of breakdowns so that profitability can be augmented. The present work employs an on-line machine monitoring scheme and an off-line machine monitoring scheme in conjunction with reloading of part types to cope with the breakdowns. The proposed model bears similarity with the dynamic environment of FMS, hence, t...

A mixed-model assembly line is a type of production line where a variety of product models similar in product characteristics are produced. As a consequence of introducing the just-in-time (JIT) production principle, it has been recognised that a U-shaped assembly line system offers several benefits over the traditional straight line system. This paper proposes a new evolutionary approach to deal with workload balancing problems in mixed-model U-shaped lines. The proposed method is based on the multi-decision of an amelioration structure to improve a variation of the workload. This paper considers both the traditional straight line system and the U-shaped assembly line, and is thus an unbiased examination of line efficiency. The performance criteria considered are the number of workstations (the line efficiency) and the variation of workload, simultaneously. The results of experiments enhanced the decision process during multi-model assembly line system production; thus, it is therefore suitable for the a...

Previously, we introduced a new method for improving commonality in a highly customized, low volume product line using component product platforms. The method provides a bottom-up platform approach to redesign family members originally developed one-at-a-time to meet specific customer requirements. In this paper, we extend the method with an Activity-Based Costing (ABC) model to specifically capture the manufacturing costs in the product line, including the cost associated with implementing a platform strategy. The valve yoke example is revisited in this paper, the customized ABC model is defined, two design strategy alternatives are addressed, and the new method is used to determine which alternative is better at resolving the tradeoff between commonality, total cost, and product performance. The proposed method shows promise for creating a product platform portfolio from a set of candidate component platforms that is most cost-effective within an existing product line. The proposed method allows for arbitrary leveraging as it does not rely solely on the traditional vertical, horizontal, or beachhead strategies advocated for the market segmentation grid, and this is especially beneficial when applied to an existing product line that was develop one-at-a-time time such that artifact designs are inconsistent from one to another.Copyright © 2008 by ASME

This paper assesses the hypothesis that plant build complexity impacts quality, suggests mechanisms to explain how complexity impacts quality, and offers countermeasures to mitigate this impact. We analyse automotive assembly data that supports the proposition that plant build complexity negatively impacts quality. In addition, this paper provides actual automotive assembly line work instructions and shows how they can be represented by the Gilbreths’ fundamental work elements and plant build complexity impacts these work elements. To highlight complexity's adverse impact on quality, we compare the actual work instructions at two automotive assembly line stations–one with very little complexity and one with extreme complexity. We list common automotive assembly quality lapses and describe how they can be caused or exacerbated by complexity. Finally the paper presents practical countermeasures to mitigate complexity's impact on quality. While based on the automotive industry, the lessons apply to all compl...

Pull systems focusing on throughput time control and applicable in situations with high variety and customisation are scarce. This paper compares three unit-based pull systems that can cope with such situations: POLCA, CONWIP and m-CONWIP. These systems control the shop floor throughput time of orders by limiting the number of orders on the shop floor. However, their effectiveness in terms of reducing total throughput time is questioned. Theory states that an improvement in the average total throughput time will be due to the workload balancing capability of a pull system, but that many pull systems lack this capability. This paper shows that this workload balancing capability exists for POLCA and m-CONWIP, but not for CONWIP. The magnitude of the effect differs strongly, depending on the configuration of the system, the order arrival pattern and the variability of the processing time of the orders.

The shortening of product delivery lead-times can usually be achieved by keeping high-level components in inventory, however in small-volume production systems, maintaining such inventories is often a costly as well as a risky business strategy. If the risk of maintaining unsold inventory can be decreased, even small-volume manufacturers may be able to justify holding more significant quantities of versatile inventory. This paper discusses a component commonality effect to breakthrough the trade-off relationship between inventory levels and delivery lead-times for such small-volume production systems. By using the same component in different products, inventory maintenance costs can be dramatically reduced, but component commonality design problems are inherently complex, since excessive module commonality may lead to lower product performances, and there are trade-off relationships between product performance and cost reductions obtained through component commonality. In this paper, such a design problem...

This paper deals with dynamic stochastic situations faced by supply chains. In this context, various interactions, disparate decisions and random phenomena must be considered. These issues are considered in this paper through a two stage supply chain control problem. The supplier and the transformation stage are both subject to random events such as periods of unavailability due to internal difficulties or market constraints. Our objective is to find information sharing control policies for the supply and production activities that minimises the expected discounted cost of ordering, inventories/backlog and transformation over an infinite horizon. This is an optimal control problem with state constraints and hybrid dynamics of the production and replenishment activities. It is shown that, from a mathematical point of view, the considered problem is difficult to tackle and it calls upon optimal and impulsive control theory notions. A dynamic stochastic model is thus proposed. The existence of an optimal con...

In today's digital economy, web-based integration of the enterprises to form an e-supply chain is a critical weapon for orchestrating the whole supply chain towards competitiveness. This paper intends to discuss the requirements for forming an e-supply chain from different perspectives, such as integration with the legacy systems, timing and prior presence of ERP (enterprise resources planning) systems, BPR (business process re-engineering) needs of internal and external business processes and business intelligence/decision support needs. A look at technical knowledge and structure to construct an e-supply chain is provided. Challenges involved in forming an e-supply chain are also briefly mentioned as a separate section in this paper. During the study, requirements are gathered by making a review of recent literature.

This paper addresses finite-capacity planning (or medium-term scheduling) issues in a flexible flow line such as a semiconductor fabrication (Fab), liquid crystal display (LCD) Fab, or printed circuit board (PCB) Fab. In such a flexible flow line, medium-term schedules such as release schedules and output schedules are critical to achieving the goal of full-capacity and on-time production. However, existing finite-capacity planning methods do not adequately reflect the actual capacity profiles of the Fab. This paper presents capacity-filtering algorithms for generating a finite-capacity loading-profile from an infinite-capacity loading-profile at a processing stage in a Fab. In addition, two types of finite-capacity planning problems are described, and ways to use the algorithms in solving these problems presented. Performance analyses using a real-life case study show that the proposed method is superior to existing methods. It is postulated that the results presented can be used as a building block for ...

This paper addresses the deadlock control problem for the autonomous vehicle storage and retrieval system (AVS/RS). For an AVS/RS with several autonomous vehicles running in bi-direction, deadlock control is one of the key issues in the implementation of AVS/RS. The cycle-deadlock is the main type of deadlock in AVS/RS. In the paper, the dynamic model of AVS/RS is investigated by using coloured timed Petri nets (CTPN). Based on the CTPN model, a route digraph is built to detect cycle-deadlock in AVS/RS with digraph tools; the necessary and sufficient conditions of deadlock-free are established. Moreover deadlock-free control policies are proposed, the critical state in deadlock free is also identified and FCFS policy is applied to solve it. Finally, a case study is given to validate the policies.

Supply chain management is and has been a popular research topic in recent years. Among the reported studies, coordination is an important ingredient to improve the performance of supply chains subject to the presence of system dynamics. This paper sets out to review some recent supply chain studies in the last decades that are related to coordination among supply chain members regarding supply chain dynamics. Focus is put on inventory management problems. More than a hundred research papers are reviewed and they are broadly categorised into analytical approaches and simulations approaches. They are further divided into sub-categorises. Observations of each category are summarised in this paper so that characteristics of each of which could be comprehended. In addition, the concluding section reveals some insights that could be considered for future research regarding coordination in supply chains and supply chain systems dynamics.

This paper illustrates the process monitoring strategy for a multistage manufacturing facility with the aid of cluster analysis and multiple multi-block partial least squares (MBPLS) models. Traditionally, a single MBPLS model is used for monitoring multiple process and quality characteristics. However, modelling all the responses together in a single model may cause poor model fit in the events of: (i) uncorrelated response variables; and (ii) groups of response variables having high correlation amongst the variables within a group but no or negligible correlations between the groups. This paper overcomes this problem by combining cluster analysis with MBPLS through development of multiple MBPLS models. Each of the MBPLS models is used to detect out-of-control observations and a superset of the out-of-control observations is created. Two new fault diagnostic statistics for stage-wise and variable-wise contribution are developed for the superset. The developed methodology is applied to a steel making shop...

In this paper we aim to give insight to how manufacturing strategies, represented by manufacturing paradigms are linked to different approaches to knowledge. Strategies are closely related to the development of core competence and how to deal with knowledge in general. In this paper we focus on how the different manufacturing strategies represent different challenges when it comes to knowledge creation and knowledge transfer. Our discussion has references to suppliers in the automotive industry, represented by a Scandinavian case. In this case the focus is on lean principles, which in contrast to mass manufacturing, represents attention to the synthetic knowledge base and tacit knowledge. Mass manufacturing, which is also still relevant in the automotive industry, is more centralised in its approach to knowledge and is focusing more on the analytical knowledge base and explicit knowledge. Knowledge should be a central part of companies’ strategies, also functional such as within manufacturing, and should ...

This paper aims to provide a combinatory approach towards addressing the advanced available-to-promise (ATP) problem, consisting of three deterministic optimisation models that operate on both sides of the Customer Order Decoupling Point. The proposed approach is based on long-term aggregate capacity reservation for periods when increased volatility is expected, while still obtaining production plans that meet the predefined and agreed customer service levels. The three optimisation models together guide a system that helps manufacturers to optimally decide on ATP quantity and due date quoting on the basis of available manufacturing resources. To support this system, a prototype software module was designed and implemented in Java that loosely integrates with the popular Open Source ERP system Compiere2's databases and uses the Linear Programming solver QS-Opt to solve the models developed in this research. The system response times as evidenced in the experiments described in this paper are quite accepta...

This paper is aimed at providing a broad review of the main approaches to supplier-related issues especially supplier selection, supplier–buyer relationships, supplier–buyer flexibility in relationships in a dynamic supply chain, through the description of the main characteristics, techniques, ongoing developments and research activities. Also, the issues relating to integration of core processes across organisational boundaries through improved communication, partnerships, alliances and cooperation are addressed, with its inherent focus on Web-enabled collaboration among the suppliers and the buyers. The aim of this paper is to consolidate the existing research efforts concerning the supplier-related issues, and to identify promising emerging issues for further study in this area. More specifically, this work analyses how diverse modelling techniques such as agent technology, petri nets, fuzzy logic and data mining can be applied to support dynamic supply chain configurations with reference to supplier-r...

As one of the most important planning and operational issues in manufacturing systems, production scheduling generally deals with allocating a set of resources over time to perform a set of tasks. Recently, control theoretic approaches based on nonlinear dynamics of continuous variables have been proposed to solve production scheduling problems as an alternative to traditional production scheduling methods that deal with decision-making components in discrete nature. The major goal of this paper is to improve predictability and performance of an existing scheduling model that employs the control theoretic approach, called distributed arrival time controller (DATC), to manage arrival times of parts using an integral controller. In this paper, we first review and investigate unique dynamic characteristics of the DATC in regards to convergence and chattering of arrival times. We then propose a new arrival time controller for the DATC that can improve predictability and performance in production scheduling. We call the new mechanism the double integral arrival-time controller (DIAC). We analyse unique characteristics of the DIAC such as oscillatory trajectory of arrival times, their oscillation frequency, and sequence visiting mechanism. In addition, we compare scheduling performance of the DIAC to the existing DATC model through computational experiments. The results show that the proposed system can be used as a mathematical and simulation model for designing adaptable manufacturing systems in the future.

While the poor response implications of supply are often not elaborated on in the literature, postponement has recently been mentioned as a useful tool for managing supply risk and disruptions. To interpret this in a more complete manner, this paper has attempted to explore the role of postponement in supply chain risk management from a complexity perspective. After a review of the relevant literature, it first draws insights emerging from normal accident theory that addresses the system characteristics of catastrophic accidents and applies them to supply chain disruptions. This is followed by the utilisation of normal accident theory to explain the role of postponement in supply chain risk management. Building on this, this paper also investigates the complexity implications of some commonly recommended measures to mitigate supply chain disruptions. In certain circumstances, the introduction of those measures may add to the complexity of a system and thus become inherently infeasible. The paper concludes with a summary and some suggestions for further research.

This paper considers a real-world two-dimensional strip packing problem involving specific machinery constraints and actual cutting production industry requirements. To adapt the problem to a wider range of machinery characteristics, the design objective considers the minimisation of material length and the total number of cuts for guillotinable-type patterns. The number of cuts required for the cutting process is crucial for the life of the industrial machines and is an important aspect in determining the cost and efficiency of the cutting operation. In this paper we propose the application of evolutionary algorithms to address the multi-objective problem, for which numerous approaches to its single-objective formulation exist, but for which multi-objective approaches are almost non-existent. The multi-objective evolutionary algorithms applied provide a set of solutions offering a range of trade-offs between the two objectives from which clients can choose according to their needs. By considering both th...

In lean manufacturing environments, cross-training is often used to achieve multi-skilling in order to increase flexibility in meeting fluctuating demand, to create a shared sense of responsibility, and to balance workload between cross-trained workers. This paper presents a model that assigns workers to tasks within a lean manufacturing cell while minimizing net present cost. In determining how to assign workers to tasks, the model addresses production requirements to meet customer demand, skill depth requirements for tasks, varying quality levels based on skill depth, and job rotation to retain skills for a cross-trained workforce. The model generates an assignment of workers to tasks and determines the training necessary for workers to meet skill requirements for tasks and customer demand. While the model can be used in a number of ways, in this paper it is used to generate a worker assignment schedule for cross-trained workers in a dedicated lean manufacturing cell in an electronics assembly plant and to evaluate the effect of increased cross-training on the cell. The resulting worker assignment schedules for the current state and several alternative scenarios for the cell are evaluated using cost results from the optimization model and from a simulation model to assess additional performance metrics. These results demonstrate the usefulness of the worker assignment model and indicate that moderate increases from current cross-training levels are not beneficial for this cell.

This paper reports a research which was pursued with the purpose of indicating the need of amalgamating mass customisation and agile manufacturing principles for achieving competitiveness in organisations. The research findings and observations on these principles were used to design a model named as agile customisation programme. The implementation study of this programme was conducted in an electronics switches manufacturing company situated in India. The practical implications of this programme were studied by gathering feedback from the executives of this company. The details of these works are briefly presented in this paper. Further, the practical implications were used to propose a roadmap. Future researchers may adopt this roadmap and implement this programme in various types and sizes of companies. The performance of this programme in those companies shall be measured using agile manufacturing metrics such as responsiveness, time compression, quality improvement and profitability.

The aim of this paper is to categorise difficulties related to release and use of information for materials supply systems design during product development projects as well as specific approaches to deal with them. In the literature it has been argued that materials supply systems design should form one dimension of concurrent engineering and be coordinated with product and production systems design although little research on how to manage it has been presented. The research presented in this paper is based on multiple sources of data, mainly gathered by means of three case studies conducted at two companies from the automotive industry. The difficulties are categorised in terms of whether or not they are related to a concurrent engineering context. The approaches are categorised with regard to whether or not they focus on difficulties related to a concurrent engineering context, and whether or not they focus on the materials supply systems designers and their work.

Customers benefit from the ability to select their desired options to configure final products. Manufacturing companies, however, struggle with the dilemma of product diversity and manufacturing complexity. It is important, therefore, for them to capture correlations among the options provided to the customers. In this paper, a data mining approach is applied to manage product diversity and complexity. Rules are extracted from historical sales data and used to form sub-assemblies as well as product configurations. Methods for discovering frequently ordered product sub-assemblies and product configurations from ‘if-then’ rules are discussed separately. The development of the sub-assemblies and configurations allows for effective management of enterprise resources, contributes to the innovative design of new products, and streamlines manufacturing and supply chain processes. The ideas introduced in this paper are illustrated with examples and an industrial case study.

Up-to-date market dynamics and decentralisation have brought about the need of flexible and robust organisational structures for manufacturing resources. To meet the need of such an environment, the manufacturing system should be equipped with an open, reconfigurable and scalable organisational structure. This paper proposes a novel organisational model, referred to as a relation-driven fractal organisation, to meet the requirements. The proposed model applies the concept of a fractal to its organisational structure and adopts a relational pattern between composing entities as a basic building block for organising. In this paper, the existing fractal-like systems involved in manufacturing systems are investigated, and the fractal organisation is derived as their super-ordinate concept. Then, r-FrMS, a relation-driven fractal organisation applied into distributed manufacturing systems, is proposed along with its organising mechanism which adopts employment relations between manufacturing resources as its o...

International audience; The paper presents a method for the analysis and design of industrial production systems based on a joint assessment of the cost and the quality of service. The operation of a production system is seen as the accomplishment of a sequence of missions, each one corresponding to the cost-effective production and delivery of a specified quantity of products within a specified time frame. The paper shows that the probability of successfully accomplishing a mission is a non linear function of the cumulative production downtime and that this time can not be obtained using conventional Markov based techniques. The paper also introduces an analytical model and a procedure that allows the density function of the downtime to be obtained and shows how, using these tools, the production costs and the quality of service may be assessed and related to the internal design of the shop floor. The method seems to be particularly valuable in the analysis of production systems integrated in just-in-time supply chains, in which the reliability of the deliveries is an outstanding requirement.

The purpose of this paper is to present a measuring approach of process flexibility under bill of material (BOM) constraints. For the manufacturing system that consists of multiple assembly lines, this paper differentiates process flexibility under BOM constraints into two hierarchical and highly interrelated levels: the assembly line level and the system level. By interpreting process flexibility as the ability to shift capacity among different parts or product types in the face of external and/or internal changes, approaches for measuring process flexibility on the two levels are proposed. Results of simulation experiments illustrate that the developed measures are effective and widely applicable to real manufacturing systems. Since the proposed measures synthesise the multiple capabilities of the manufacturing system and the impacts of BOM constraints of products, they lay the foundation of developing general guidelines for improving flexibility of the manufacturing system.

This paper reports a study on a real three-echelon supply chain operating in the beverage sector. The authors, starting from the actual supply chain configuration, propose a detailed study of the inventory systems. The test of a comprehensive set of different operative scenarios, in terms of customers’ demand intensity, customers’ demand variability and lead times, becomes a powerful tool for inventory systems analysis along the supply chain. The main objective is the comparison of the actual supply chain configuration with optimistic and pessimistic scenarios for studying the behaviour of different inventory control policies and optimizing the inventory system of each supply chain node. Due to the dynamically changing and stochastic behaviour of the supply chain variables as well as the complex interactions among its actors, the authors have been pushed to implement an advanced simulation model supported by a ‘well-planned’ experimental design. In addition the paper aims to underline the research effort ...

This paper presents an improvement on earlier work on a common weight multi-criteria decision-making (MCDM) approach for technology selection by (Karsak, E.E. and Ahiska, S.S., Practical common weight multi-criteria decision-making approach with an improved discriminating power for technology selection. Int. J. Prod. Res., 2005, 43, 1537-1554.) benefiting from a bisection search algorithm. The proposed algorithm enables to calculate the values of discriminating parameter, k, which appears in the introduced efficiency measure, in a systematic and robust manner rather than requiring the decision analyst to assign an arbitrary step size value. In addition, the paper presents comments on the model proposed by (Amin, G.R., Toloo, M. and Sohrabis, B., An improved MCDM DEA model for technology selection. Int. J. Prod. Res., 2006, 44, 2681-2686.) for technology selection. Finally, the robustness of the proposed decision-making framework is illustrated via several numerical examples taken from the above-mentioned papers.

Process drift is a common occurrence in many manufacturing processes where machines become dirty (leading to more contamination) or processing parameters degrade, negatively affecting system performance. Statistical process control tracks process quality to determine when the process has gone out of control (has drifted beyond its specifications). This paper considers the case where parts examined at a downstream inspection station are used to determine when the upstream process is out of control. The manufacturing cycle time from the out of control process to the downstream inspection process influences the detection time that elapses until the out of control process is noticed and repaired. Because an out of control process produces more bad parts, the detection time affects the number of good parts produced and the throughput of the manufacturing system. This situation is common in many industries but no models of the phenomena exist. This paper presents a novel manufacturing system model based on queu...

This paper investigates the problem of designing cellular manufacturing systems with multi-period production planning, dynamic system reconfiguration, operation sequence, duplicate machines, machine capacity and machine procurement. An important aspect of this problem is the introduction of routing flexibility in the system by the formation of alternate contingency process routings in addition to alternate main process routings for all part types. Contingency routings serve as backups so as to effectively address the reality of part process routing disruptions (in the main routings) owing to machine breakdowns and allow the cellular manufacturing system to operate in a continuous manner even in the event of such breakdowns. The paper also provides in-depth discussions on the trade-off between the increased flexibility obtained versus the additional cost to be incurred through the formation of contingency routings for all parts. Some sensitivity analysis is also performed on some of the model parameters. The problem is modelled and solved through a comprehensive mixed integer programming formulation. Computational results presented by solving some numerical examples show that the routing and process flexibilities can be incorporated within the cellular manufacturing system design without significant increase in the system cost.