A genetic algorithm for solving a multi-floor layout design model of a cellular manufacturing system with alternative process routings and flexible configuration

This paper presents a novel integer linear programming model for designing multi-floor layout of cellular manufacturing systems (CMS). Three major and interrelated decisions are involved in the design of a CMS; namely cell formation (CF), group layout (GL), and group scheduling (GS). A novel aspect of this model is concurrently making the CF and GL decisions to achieve an optimal design solution in a multi-floor factory. Other compromising aspects are: multi-floor layout to form cells in different floors is considered, multi-rows layout of equal area facilities in each cell is allowed, cells in flexible shapes are configured, and material handling cost based on the distance between the locations assigned to machines are calculated. Such an integrated CMS model with an extensive coverage of important manufacturing features has not been proposed before and this model incorporates several design features including alternative process routings, operation sequence, processing time, production volume of parts, duplicate machines, machine capacity, new machine purchasing, lot splitting, material flow between machines, intra-cell layout, inter-cell layout, multi-floor layout and flexible configuration. The objective is to minimize the total costs of intra-cell, inter-cell, and inter-floor material handling, new machines purchasing and machine processing. Two numerical examples are solved by the Lingo software to verify the performance of the proposed model and illustrate the model features. Sensitive analysis is also implemented on some model parameters. An improved genetic algorithm (GA) is proposed to derive near-optimal solutions for the integrated model because of its NP hardness. It is then tested using several problems with different sizes and settings to verify the computational efficiency of the developed algorithm in comparison to a classic simulated annealing algorithm and the Lingo software. The obtained results show the efficiency of proposed GA in terms of objective function value and computational time.     

Applying simulated annealing to cellular manufacturing system design

Cell formation and cellular layout design are the two main steps in designing a cellular manufacturing system (CMS). In this paper, we will present an integrated methodology based on a new concept of similarity coefficients and the use of simulated annealing (SA) as an optimization tool. In comparison with the previous works, the proposed methodology takes into account relevant production data, such as alternative process routings and the production volumes of parts. The SA-based optimization tool is parallel in nature and, hence, can reduce the computation time significantly, so it is capable of handling large-scale problems. Finally, the SA-based procedure is compared with a genetic algorithm (GA) based procedure and it will be shown that the SA-based algorithm can be as effective as a GA-based algorithm, but with less computational time and effort.     

Layout Planning Technology of Cellular Manufacturing System Based on Process Interconnection Analysis

With sustaining change of production mode,layout planning is no longer a thing built once for all.Cellular layout(CL) is becoming a hotspot in the research field of manufacturing system layout.Traditional researches on layout planning are mainly concentrating on aspects of layout arithmetic,style and evaluation,etc.Relatively seldom efforts are paid to CL and its specific problems as cell formation(CF),equipment sharing and CL analysis.Through problem analyzing of layout in cellular manufacturing system(CMS),research approach of cell formation,interactive layout and layout analysis threaded with process interconnection relationship(PIR) is proposed.Typical key technologies in CL like CF technology based on similarity analysis of part processes,interactive visual layout technology,layout evaluation technology founded on PIR analysis and algorithm of cell equipment sharing are put forward.Against the background of one enterprise which encounters problems of low utility of key equipments and disperse material logistic,an example of four-cell layout is given.The CL adjustment and analysis results show that equipment with high level of sharing degree should be disposed around the boundary of its main cell,and be near to other sharing cells as possible;process route should be centralized by all means,so equipment adjustment is to be implemented along direction that route intersection can be decreased;giving consideration to the existence of discrete cell,logistic route and its density should be centralized to cells formed.The proposed research can help improve equipment utility and material logistic efficiency of CL,and can be popularized to other application availably.     

Integrating cell formation with cellular layout and operations scheduling

Designing a cellular manufacturing (CM) system involves three major decisions: cell formation (CF), cellular layout (CL), and cellular scheduling (CS). The integrated design of CM systems is investigated in this paper by proposing two mathematical models. The first model integrates cellular layout problem with cell formation problem to determine optimal cell configuration and the layout of machines and cells in order to minimize the total movement costs. The second model takes also the cellular scheduling into consideration with the objective of minimizing the total completion time of parts. Two genetic algorithms are developed to solve the real-sized problems. The proposed models are formulated as mixed integer linear programming, and two numerical examples are solved in order to investigate the effects of integration in the CM systems design. The results show that considering CF, CL, and CS decisions in a simultaneous manner can significantly improve the performance of the CM systems.     

A flow matrix-based heuristic algorithm for cell formation and layout design in cellular manufacturing system

Cellular manufacturing is a successful application of group technology (GT) concepts. The aim of a cellular manufacturing system (CMS) is to identify similar manufacturing processes and features where machines are grouped into machine cells based on their contributions to the production process. In the last three decades of research in cell formation, researchers have mainly used zero-one machine component incidence matrix as the input data for the problem. However, recently efforts have been made to use other data structures, such as interval data and ordinal data (consisting of sequence of processing). Sequence data provide valuable information about the flow patterns of various jobs in a manufacturing system. This study develops a heuristic algorithm based on flow matrix for cell formation and layout design in a simultaneous fashion using sequence data. The numerical results of the algorithm on the available problems in the literature indicate the usefulness of the algorithm regarding to performance indices.     

A genetic algorithm for the inter-cell layout and material handling system design

The traditional optimization processes for the cell system layout (CSL) and material handling system in cellular manufacturing systems (CMSs) were carried out sequentially and separately. The solutions obtained by this means can be far from the total optimum. In this paper, an integrated approach to the problem is proposed that attempts to design CSL and flow path structure simultaneously. The cells in question are assumed to be shape-fixed and have pre-determined pickup/delivery (P/D) stations. A sequence-pair based CSL-generating algorithm allows cells to be placed at any possible position on a continuous floor plan and leads to a corresponding feasible CSL. A grid graph for the CSL is accordingly constructed to provide possible flow paths for the layout. Then, the sum of the traveling distances, determined by the shortest path algorithm, is used to evaluate the CSL. These steps are embedded into a genetic algorithm (GA) that searches the solution space to obtain optimal layouts based on the contour distances between the P/D stations. Computational results demonstrate that the run time required to solve the test problems is quite acceptable given the long-term nature of facility layout decisions. Moreover, a comparison of the computational results with the existing methods indicates that the proposed approach is a viable alternative for effectively generating layout designs for CMS.     

Cascading flowlines and layout modules: Practical strategies for machine duplication in facility layouts

The standard approach for design of a layout for a high-variety low-volume (HVLV) manufacturing facility has been to use either a from-to chart or a multi-product process chart to design a process layout or a cellular layout, respectively, for the facility. Considerable research has focused on making a go-no go decision to implement any one of these two traditional layouts as the preferred layout for an HVLV manufacturing facility. This paper introduces a variety of Hybrid Cellular Layouts (HCLs) which integrate the attributes of the traditional functional, cellular and flowline layouts. The mathematical models and methods for design of two HCLs—cascading flowline layout and modular layout—are discussed in detail. Unlike the standard models in the literature, the design of the cascading flowline layout introduces a novel string-to-graph aggregation and planar graph embedding method that allows machine duplication in the layout. Similarly, the design of the Modular layout introduces a substring clustering method instead of the standard method of cluster analysis to form part families using the complete routings of the parts. For each HCL, results from an industry project are presented to demonstrate the real-world viability of the concepts, methods and software developed to support the design of HCLs for high-variety low-volume manufacturing facilities.     

Thermal-error modeling for complex physical systems: the-state-of-arts review

Flexibility and responsiveness to customer demands are very important for success. Generally additional time is needed for setup caused by poor design of equipment. At this point the terms continuous process improvement and SMED (single minute exchange of dies) as an approach of lean manufacturing come into play. A lean manufacturing system is part of corporate culture, like tools and approaches. In this research work, the process capability analysis technique is implemented by using MINITAB14 software to investigate the relation between SMED methodology and equipment design. The index C_pk has been used in this application study to provide a quantitative measurement of the equipment design by applying the SMED methodology in automobile manufacturing. The results of this research study indicated that SMED in other words “quick changeover” is still a suitable method not only for manufacturing improvement but also for equipment/die design development.     

复杂机械产品生产单元的组织改造

企业的精益化改造是企业成功信息化的关键因素,而生产系统组织的精益化是最根本的问题。以人为本的机械产品精益组织的特点是细胞化、自管理及团队协作。相应的设计改造过程是一个长期持续的改进过程。从设计原理、步骤到设计结果举例,结合国内航空实践,详细描述生产系统组织改造的方法,具有现实意义。     

A Cell Management System to Support Robotic Assembly

There is an increasing requirement for the assembly of wider ranges of products in relatively small lot sizes. Consequently, robots are seen as being attractive as an assembly method. There has been much work on developing advanced robot grippers and applying vision systems/artificial intelligence. There has, however, been relatively little work on the overall problem of controlling robotic assembly cells (RACs) and their integration into the wider manufacturing organisation. This paper describes the design of a cell management system (CMS) based on a standard personal computer. The CMS supports RAC operations by managing/presenting data relevant to the cell operator. It also provides an interface between the cell and other organisational computer systems. Furthermore, the CMS allows error checking and recovery functionality to be implemented within an RAC without the need for modifications to the robot controller. Finally, the paper describes a pilot cell developed to test the CMS design.     

Concurrent cell formation and layout design using scatter search

Two key decisions in designing cellular manufacturing systems are cell formation and layout design problems. In the cell formation problem, machine groups and part families are determined while in the facility layout problem the location of each machine in each cell (intra-cell layout) and the location of each cell (inter-cell layout) are decided. Owing to the fact that there are interactions between two problems, cell formation and layout design problem must be tackled concurrently to design a productive manufacturing system. In this research, two problems are investigated concurrently. Some important and realistic factors such as inter-cell layout, intra-cell layout, operations sequence, part demands, batch size, number of cells, cell size, and variable process routings are incorporated in the problem. The problem is formulated as a mathematical model. Three different methods are described to solve the problem: multi-objective scatter search (MOSS), non-dominated genetic algorithm (NSGA-II), and the ε-constraint method. The methods are employed to solve nine problems generated and adopted from the literature. Sensitivity analysis is accomplished on the parameters of the problem to investigate the effects of them on objective function values. The results show that the proposed MOSS algorithm performs better than NSGA-II and produces better solutions in comparison to multi-stage approaches.     

A system for design of multicavity die casting dies from part product model

Design of a die casting die is a nontrivial task, which depends upon a number of influencing factors related to material, part geometry, manufacturing resources, cost, delivery time, etc. Complexity of this die design activity further increases in case of a multicavity die. Currently available die design systems lack in the level of automation and do not explicitly address multicavity die design. Present work is an attempt to develop a system, which facilitates computer-aided design of a multicavity die casting die. The objective of the proposed system is to automate the process of deciding number of cavities, design of cavity layout and die–base, and core and cavity creation for a multicavity die casting die. The proposed system, which we named Auto_Die_Caster, works as an add-on application to solid modeling software SolidWorks. The proposed system is divided into four modules, namely data initialization, cavity design, cavity layout and die–base design, and core–cavity design. Use of commercial software like SolidWorks as a platform both for part design and generation of die design eliminates loss of data which makes the proposed system quite useful in the industrial scenario. To demonstrate the capabilities of Auto_Die_Caster, it was tried for a number of die casting parts and the results are presented. Proposed system is a step forward to design manufacturing integration for die casting process.     

An integrated fuzzy DEA–fuzzy C-means–simulation for optimization of operator allocation in cellular manufacturing systems

This paper presents an integrated fuzzy data envelopment analysis (FDEA), fuzzy C-means and computer simulation for optimization of operator allocation in cellular manufacturing systems (CMS). This is a challenging issue in flexible manufacturing systems in general and in CMS in particular. A computer simulation model, which considers various operators layout, is developed. For considering more information from computer simulation report, the output data is fuzzified. FDEA is utilized to assess simulation alternatives in various levels of uncertainty. In addition, FDEA ranking of decision-making units are clustered by fuzzy C-means method. Each of the clusters indicates a degree of desirability for operator allocation. Previous studies only utilize multivariate analysis methods and simulation, whereas this study uses an integrated simulation, fuzzy DEA, fuzzy C-means, and fuzzy indicators. Furthermore, previous CMS studies consider only one type of product, whereas this study considers multiproduct for CMS modeling through simulation. Moreover, more robust CMS assessment indicators are used in the proposed model. A practical case study illustrates the effectiveness and superiority of the proposed methodology. In addition, we compared the results of U shape with other production types, namely spiral, straight, L, W, zigzag, and Z. Moreover, we show that it dominates the other production types.     

Optimization and implementation of cellular manufacturing system in a pump industry using three cell formation algorithms

In recent years cellular manufacturing has become an effective tool for improving productivity. Attainment of full benefits of cellular manufacturing depends firstly on the design of the machine cells and part families and secondly on the method of operation which take full advantages of cell properties. Inappropriate methods of loading and scheduling can even lead to the failure of cellular manufacturing systems (CMS), however efficiently the cell is designed. This paper examines three array-based clustering algorithms, namely rank order clustering (ROC), rank order clustering-2 (ROC2) and direct clustering analysis (DCA) for manufacturing cell formation, with a real-life example to demonstrate the effectiveness of various clustering algorithms. The machine cell formation methods considered in this comparative and evaluative study belongs to the cluster formation approach of solving the MCF problem. The most effective method is selected and used to build the cellular manufacturing system. The comparison and evaluation are performed using four published performance measures and compares the improvements with the existing conventional system and the cellular manufacturing system. The above algorithms were written in the C++ language on an Intel/Pentium III-PC-compatible system.     

Design of loop layout in flexible manufacturing system using non-traditional optimization technique

Layout arrangement is important to achieve high productivity in flexible manufacturing system (FMS). This paper discusses the design of loop layout in FMS. The objective of the loop layout problem is the determination of the ordering of machines around a loop, to minimize the total number of loop traversals for a family of parts. This paper details the design, development and testing of particle swarm optimization (PSO) technique to solve the loop layout problem. The proposed method is validated with bench mark problems. The clearance between the machines is also considered in the design of loop layout. This aspect aids in selecting the best layout.     

Approach to the production environment design task within factory coordination

In a discrete parts batch manufacturing environment, there are different data flows concerning the design of products and manufacturing facilities, customer orders, purchase of materials, production control and delivery of orders. Traditionally, because of the functional allocation of tasks within an organization, there is little integration of information between the production control task and the design of manufacturing facilities. One of the objectives of the design of manufacturing facilities tasks is to efficiently organize a production environment to manufacture a range of products. With a greater relationship between these two tasks, we feel that the complexity of the production control task is reduced. This reduction in complexity arises from a reduction in the range of possible problems that can occur and an increase in the predictability of events through more effective organization of a production environment. Factory coordination is part of an approach to shopfloor control which recognizes this principle by establishing a relationship between the design of a production environment and the control of product flow throughout a factory. This relationship is established through a modular architecture for factory coordination. The production environment design element of the architecture for factory coordination is concentrated on. Using a methodology for describing systems, known as SADT, three main tasks associated with this approach are described; process planning, maintenance of a cellular layout, and manufacturing systems analysis.     

A concurrent engineering based method for developing a baby carriage

An integrated concurrent engineering methodology for developing a baby carriage is proposed. The development process is divided into three stages for considering the design, manufacture, and assembly problems. The product is first designed based on design criteria to ensure the best matching of needs and requirements. Then the parts and machine tools are coded using group technology (GT). The machine groups and the parts to be processed are given in matrix form using the production flow analysis (PFA) method. The machine cells are arranged based on the balance analysis of process time, and a flexible manufacturing system (FMS) is planned. Finally, the assembly line is planned based on the relationship of the parts. Some related parts are collected as a subassembly system. After the subassembly is decided, the work stations are arranged based on the required assembly time to obtain a high-performance assembly line. The results show that not only is the production cost of the product reduced, but also that the competitive properties are improved. This model can also be applied to develop other products.     

Evaluation of dispatching rules for cellular manufacturing

In this paper, the effects of various dispatching rules on the operation and performance of cellular manufacturing systems (CMS) are evaluated. When the study of a CMS considers the automated material handling, it is crucial to reduce the gridlock probability (i.e., the probability of an unsuccessful load transfer attempt occurring in the interface point between the intercell and intracell handling system). Preventing an unsuccessful load transfer is critical for the operation of the entire system as a blockage between the automated guided vehicle (AGV) and the overloaded cell results in a total system shutdown. The gridlock probability is influenced by the dispatching rule used to schedule the load transfers in the system. Therefore, in order to reduce this probability it is necessary to use a dispatching rule that will decrease the number of waiting loads in the transfer spurs. The main objective of the paper presented herein is to identify a dispatching rule that maintains the system operational at all times. A group of dispatching rules, including the first come first served (FCFS), shortest imminent operation (SI), longest imminent operation (LI), most remaining operations (MRO), shortest processing time (SPT), shortest remaining process time (SR), and a newly developed rule proposed by the authors, loads with the minimum number of processing first (MNP), are tested and evaluated with respect to whether the capacity of the transfer spurs of the cells is exceeded. This paper presents a simulation model of a cellular manufacturing system, which is used to further explore the effects of the dispatching rules on the system performance. The results show superior performance of the newly proposed MNP rule.     

多品种跨批量企业混合布局方式下的精益配送模型研究

多品种跨批量企业生产具有产品品种繁多、工艺复杂、产量多变等特点,缺乏拉动式准时生产的条件,在生产过程中容易存在半成品大量积压、产品生产周期过长等问题。针对这一问题,介绍一种不同于拉动式生产的工位物料的准时配送方法,利用混合布局方式,结合几个精益配送技术模块,提出了多品种跨批量企业的精益生产物料配送模型,使生产时的原材料和半成品在工位间高效流转,缩短产品生产周期,提高生产效率。     

Evaluation of dispatching rules for cellular manufacturing

In this paper, the effects of various dispatching rules on the operation and performance of cellular manufacturing systems (CMS) are evaluated. When the study of a CMS considers the automated material handling, it is crucial to reduce the gridlock probability (i.e., the probability of an unsuccessful load transfer attempt occurring in the interface point between the intercell and intracell handling system). Preventing an unsuccessful load transfer is critical for the operation of the entire system as a blockage between the automated guided vehicle (AGV) and the overloaded cell results in a total system shutdown. The gridlock probability is influenced by the dispatching rule used to schedule the load transfers in the system. Therefore, in order to reduce this probability it is necessary to use a dispatching rule that will decrease the number of waiting loads in the transfer spurs. The main objective of the paper presented herein is to identify a dispatching rule that maintains the system operational at all times. A group of dispatching rules, including the first come first served (FCFS), shortest imminent operation (SI), longest imminent operation (LI), most remaining operations (MRO), shortest processing time (SPT), shortest remaining process time (SR), and a newly developed rule proposed by the authors, loads with the minimum number of processing first (MNP), are tested and evaluated with respect to whether the capacity of the transfer spurs of the cells is exceeded. This paper presents a simulation model of a cellular manufacturing system, which is used to further explore the effects of the dispatching rules on the system performance. The results show superior performance of the newly proposed MNP rule.