Optimal configuration selection for Reconfigurable Manufacturing Systems

The selection of Reconfigurable Manufacturing Systems (RMS) configurations that include arrangement of machines, equipment selection, and assignment of operations, has a significant impact on their performance. This paper reviews the relevant literature and highlights the gaps that exist in this area of research. A novel “RMS Configuration Selection Approach” is introduced. It consists of two phases; the first deals with the selection of the near-optimal alternative configurations for each possible demand scenario over the considered configuration periods. It uses a constraint satisfaction procedure and powerful meta-heuristics, real-coded Genetic Algorithms (GAs) and Tabu Search (TS), for the continuous optimization of capital cost and system availability. The second phase utilizes integer-coded GAs and TS to determine the alternatives, from those produced in the first phase, that would optimize the degree of transition smoothness over the planning horizon. It uses a stochastic model of the level of reconfiguration smoothness (RS) across all the configuration periods in the planning horizon according to the anticipated demand scenarios. This model is based on a RS metric and a reconfiguration planning procedure that guide the development of execution plans for reconfiguration. The developed approach is demonstrated and validated using a case study. It was shown that it is possible to provide the manufacturing capacity and functionality needed when needed while minimizing the reconfiguration effort. The proposed approach can provide decision support for management in selecting RMS configurations at the beginning of each configuration period.

Assessing the structural complexity of manufacturing systems configurations

Modern manufacturing systems are increasingly required to be flexible and adaptable to changing market demands, which adds to their structural and operational complexity. One of the major challenges at the early design stages is to select a manufacturing system configuration that both satisfies the production functional requirements and is easy to operate and manage. A new metric for assessing the structural complexity of manufacturing system configurations is presented in this paper. The proposed complexity metric incorporates the quantity of information using an entropy approach. It accounts for the complexity inherent in the various modules in the manufacturing system through the use of an index derived from a newly developed manufacturing systems classification code. The code captures the effect of various component types and technologies used in a manufacturing system on the system’s structural complexity. The presented metric would be helpful in selecting the least complex manufacturing system configuration that meets the requirements. An engine cylinder head production system is used to illustrate the application of the proposed methodology in comparing feasible but different manufacturing system configurations capable of producing the cylinder head based on their structurally inherent complexity.     

A Further Discussion on Trends in the Development of Advanced Manufacturing Technology

This paper is a supplement to “Trends in the Development of Advanced Manufacturing Technology” (Yang and Wu in Chin. J. Mech. Eng., 39: 73, 2003) but delves deeper into it. It first points out the strategic status of manufacturing industry in state development. Then, a detailed analysis is given on the features and trends in the development of advanced manufacturing technology in a total of 12 points from three aspects: “precision,” “extreme,” and “culture” from the aspect of the product itself; “green,” “rapidness,” “saving,” and “efficiency” during the manufacturing process; and “digit,” “auto,” “integration,” “networking,” and “intelligence” in view of the manufacturing method. In addition, it emphasizes that all the above aspects should be based on two base points: “manufacture” and “machinery.” Finally, it puts forth the guiding ideologies for the development of advanced manufacturing technology and the aspects China should give priority to in development, while stressing on the principles of independence, innovation and “human orientation.”     

An optimised part-selection strategy in product reconfiguration design

Effective reuse of used parts and design experience help keep costs down and maintain a short time-to-market product cycle. Part selection aims to select pre-defined parts which can be connected in certain ways to perform some high-level functionality. Constraints are critical to the part-selection problem and are used to represent the function requirements that are decomposed or derived from design knowledge and particular customer needs. In this paper, constraints in part selection are discussed and classified into two basic types: part local constraints and part reconfiguration constraints. This paper mainly discusses part reconfiguration constraints, which are further classified into two categories: monotonic reconfiguration constraints and complex reconfiguration constraints. The part selection process is comprised of a series of decisions in a real product reconfiguration design process. The order of decisions is believed to have a significant effect on the development of the product reconfiguration design. The concept of effective selection range function was introduced to compute the total effective selection range, and a heuristic algorithm based on it is proposed in this paper, which aims to make the search process convergent with feasible results as well as to retain the maximum total effective part selection range. A case study is given and some conclusions are presented.     

基于网络的制造资源重构方法研究

提出了基于网络的制造资源重构的思路和方法,即分2个阶段实现制造资源的重构.首先是候选企业的选择,其次是制造资源的重构,并建立与之相适应的制造任务分配模式、企业信息模型和制造设备的信息模型,给出了重构过程的流程.     

敏捷制造中制造资源重构问题建模

敏捷制造是２１世纪的制造模式,这可以异地开发产品,以充分利用各个企业的资源优势。建立联盟是实施敏捷制造的关键。从产品开发的角度看,联盟的建立就是资源的重组,而车间的重构是制造资源重组的重要内容。本文从产品开发任务定义和分解出发,建立了制造资源重构的数学模型,提出了基于因特网的制造资源重构的机理和方法,同时给出了优化问题的启发式算法。     

Proposal of new eco-manufacturing feature interaction-based methodology in CAD phase

Following the environmental crises of recent decades, a turning point in the awareness of the fragility of ecosystems has been marked, i.e., environmental awareness. This has contributed to the development of various environmental laws and regulations such as the “Waste Electrical and Electronic Equipment,” the “Restriction of Hazardous Substances,” and the “Registration, Evaluation, Authorization and Restriction of Chemicals” regulations and the “Energy Using Products” Directives. Our work contributes to the development of eco-friendly product manufacturing processes. In order to estimate and optimize the environmental impacts of a product, most of the methodologies, concepts, and tools that integrate computer-aided design (CAD) and life cycle assessment systems generally exploit the feature technology at the level of each feature independently of the others, i.e., “microplanning.” The feature interaction technology (FIT) is treated only in few studies, but it is pivotal in the eco-manufacturing process. In this paper, we propose a new manufacturing-scenarios-based methodology by using FIT and a Multi-criteria Decision Support Method (MCDSM), which helps manufacturers maintain their marketplaces by producing goods in an eco-friendly way. In fact, this methodology helps designers choose from the CAD design phase the most ecological manufacturing process from possible existent scenarios in real time.     

A methodology for facilitating reconfiguration in manufacturing: the move towards reconfigurable manufacturing systems

The launch of new products to the market is essential for companies in order to remain competitive. Products are constantly being replaced for others that fulfil the changing requirements of the customers. For achieving this, companies have to adapt their production system to the new requirements of the new products by adding or removing machines, changing the lay-out, etc. Normally, this reconfiguration implies a high investment. Reconfigurable manufacturing systems (RMSs) arise for facilitating the reconfiguration of the production system, being considered as the next step in manufacturing. This paper deals with the development of a methodology based on RMSs that allows a feasible reconfiguration of production systems. This methodology is based on the ALCA algorithm from group technology, and takes into account five requirements of products on RMSs: modularity, commonality, compatibility, reusability and demand. The selection of the product families is obtained with a mathematical model specifically formulated for this purpose.     

Distributed flexible reconfigurable condition monitoring and diagnosis technology

As manufacturing becomes increasingly decentralized, flexible and reconfigurable, more research needs to be done on monitoring and diagnosis technology that accommodate these new trends. The distributed condition monitoring and diagnosis technology based on the “flexible and reconfigurable” concept is studied here. A condition monitoring diagnosis model based on the distributed flexible and reconfigurable idea is proposed in this paper. The component makeup and functions of this model are discussed in detail. The model can fulfill in most instances the manufacturing system requirements for changing the configuration of the monitoring diagnosis system according to different manufacturing system configurations. This model also realizes the flexibility and reconfigurability of the monitoring diagnosis system in some degree. The model has already spawned a successful prototype for monitoring a chemical plant in accomplishing monitoring and control of the production process and equipment. Finally, some future research work is pointed out. __________ Translated from Chin. J. Mech. Eng., 2004, 40 (3) (in Chinese)     

An environmental assessment model applied to printed circuit board manufacturing

Environmental consciousness in manufacturing is becoming increasingly important, due to market pressure and government regulations. As a result, there is an immediate need to develop a model which can effectively assess the impacts of pollution in manufacturing. In this paper, an environmental assessment model is developed based on the combining of the “interval method” with the network analytic method and fuzzy set theory. By applying fuzzy set theory and using on-site-measured pollution data, this model allows uncertain, interactive and dynamic information to be incorporated into the environmental impact assessment. The applicability of this model is demonstrated by a printed circuit board (PCB) manufacturing case. It is concluded that this model is a simple, pragmatic and effective tool for analysing the relative impacts of waste emissions and evaluating the environmental performance of manufacturing processes.     

敏捷制造单元重构算法

敏捷制造单元动态重构的实质是制造资源的优化选择及制造单元的构建。首先运用规划理论解决了针对待加工任务的可利用制造资源优化选择问题。其次，运用模糊数学理论，提出了基于粒度适中原则的模糊聚类方法，完成制造资源及待加工工件的聚合，实现了敏捷制造单元的构建。实例表明，设计的两阶段重构算法可有效地完成敏捷制造单元的重构过程，实现资源面向任务的动态优化。     

Manufacturing cell formation using modified ART1 networks

The primary objective of group technology (GT) is to enhance the productivity in the batch manufacturing environment. The GT cell formation problem is solved using modified binary adaptive resonance theory networks known as ART1. The input to the modified ART1 is a machine-part incidence matrix comprised of the binary digits “0” and “1”. And the outputs are the list of part families and the corresponding part list, machine cells and their corresponding list of machines, and the number of exceptional elements. This method is applied to the known benchmarked problems found in the literature and it is found to outperform other algorithms in terms of minimizing the number of the exceptional elements. The relative merits of using this method with respect to other known algorithms/heuristics in terms of computational speed and consistency are presented .     

e-制造系统的制造资源动态配置过程研究

传统制造资源动态配置没有涉及制造系统、制造单元和设备之间制造过程信息的重组模型,据此,在拓展传统制造资源动态配置模型的基础上,结合模糊聚类理论,研究了e制造环境下制造任务在一定批量和多工艺方案情形下的单元化配置模型,以及基于此配置结果的制造系统、动态制造单元、设备间的信息重组模型与制造过程信息跟踪方法,为“柔性制造”、“数宁化精确生产”奠定了基础,并对开发的原型系统进行验证。     

Economic and strategic perspectives on investing in RMS and FMS

The evolution of manufacturing systems, according to changing internal and external conditions, requires design and assessment techniques that consider both strategic and financial criteria to evaluate the suitability of the Flexible and Reconfigurable system solutions in addressing these variations. In this paper, a fuzzy multi-objective mixed integer optimization model to evaluate RMS investments used in a multiple product demand environment is presented. The model incorporates in-house production and outsourcing options, machine acquisition and disposal costs, operational costs, and re-configuration cost and duration for the utilized modular machines. The resulting system configurations are optimized for lifecycle costs, responsiveness performance, and system structural complexity simultaneously. A complexity metric that incorporates the quantity of information using an entropy approach is used to represent the inherent structural complexity of the considered system configurations. It accounts for the complexity of the machine modules in a manufacturing system through the use of an index derived from a newly developed manufacturing systems classification code, which captures the effect machine types and technologies on the system’s structural complexity. A metric is proposed to measure the responsiveness ability and efficiency as well as the overall capability of each machine and effectiveness of machines changeover. The application of the developed planning and assessment model that incorporates these three criteria is illustrated with a case study where FMS and RMS alternatives were compared. The suitable conditions for investing in RMS are also discussed.

Plant location selection based on fuzzy TOPSIS

The selection of plant location plays a very important role in minimizing cost and maximizing the use of resources for many companies. In this paper, a new TOPSIS approach for selecting plant location under linguistic environments is presented, where the ratings of various alternative locations under various criteria, and the weights of various criteria are assessed in linguistic terms represented by fuzzy numbers. To avoid complicated fuzzy arithmetic operations, the linguistic variables, which are represented by triangular fuzzy numbers, are transformed into crisp numbers based on graded mean representation. The canonical representation of multiplication operations on triangular fuzzy numbers is used to obtain the “positive ideal solution” and the “negative ideal solution”. The closeness efficient is defined to determine the ranking order of all alternatives by calculating the distance to both the “positive-ideal solution” and the “negative-ideal solution” simultaneously. Compared with existing fuzzy TOPSIS methods, the proposed method can deal with group decision-making problems in a more efficient manner. A numerical example of plant location selection is used to illustrate the efficiency of the proposed method.     

Implementation of a “backwards planning” technique in the automation of process planning

It is essential to automate the process-planning function to achieve true integration of CAD and NC machining for computer-integrated manufacturing. Several planning techniques have been used for this purpose and the popular method called the “bottom-up” approach or “backwards planning” has been successfully used in developing an expert process-planning system called EXCAP. This paper describes the implementation of this approach, providing details and examples of the model-updating module which enables the planning to be executed automatically for turned components.     

Research on Microelectromagnetic Relays

A new microelectromagnetic relay is presented and fabricated based on micromachining technology, aiming at the miniaturization and high manufacturing efficiency of electromagnetic relays. This microrelay is composed of a lower magnetic circuit, a planar exciting coil, and an upper magnetic armature. A complete magnetic circuit is composed, and the “ON” and “OFF” states are controlled by the current of the exciting coil. The dimension of this microrelay is 5 mm × 5 mm × 0.4–mm. The fabrication process mainly includes lithography, sputtering, electroplating, etching, sacrifice-layer technology, etc. Electromagnetic force is calculated theoretically. The calculation results are used for the optimization design of the armature and the number of turns of the exciting coil. A microelectromagnetic relay is fabricated and the initial test results are given. The resistance of the exciting coil is about 300 Ω. The switch-on state resistance is about 1.7 Ω at an exciting current of about 50–mA. Translated from Journal of Beijing University of Technology, 2004, 30(2) (in Chinese)     

Research on application of the Internet of things technology in financial leasing of intelligent manufacturing enterprises

In 2015, the State Council issued “Made in China 2025,” stating that the deep integration of information technology and manufacturing should be     

Experimental research on thermal comfort in the university classroom of regular semesters in Korea

This research has investigated physical variables affecting indoor thermal comfort and subjective responses of thermal comfort of students in a university in Korea in which the weather is oceanic temperate climate, and has been performed to contribute to the research fields of Sustainable Thermal Standard and Adaptive Thermal Comfort (ATC). This research is based on the ISO 7730-2005 standard and the ATC theories and 4 main variables of PMV such as dry bulb temperature (Ta), relative humidity (RH), black bulb temperature (Tg), and air velocity (Va) are measured once a week during two regular semesters. A clothing insulation, a thermal sensation vote (TSV), an acceptability of thermal environment, and a preference for cooling and heating are investigated at the same time using a questionnaire. This study was carried out for 26 weeks during the spring season, from March to June 2009, and the autumn season, from September to December 2009. The main achievements of this study are as follows. Monthly Mean Outdoor Temperature (MMOT) and Operative Temperature (OT) in the classroom during research periods are 7.4∼23.3°C and 17.5∼29.0°C, respectively. The acceptability ratio of thermal environment shows over 80% when the range of OT in the classroom is 17∼25°C, and the range can be applicable to operative index of heating and cooling of classroom. The mean TSV of respondents is almost “neutral (0)” when the PMV in the classroom moves to “neutral (0)” and “slightly cool (−1)”, and the TSV is almost “+1.5” when the PMV moves to “slightly warm (+1)”. The acceptability ratio of thermal environment is slightly different from ASHRAE Standard 55-2004. So it is necessary to more investigate standard range of acceptability of thermal environment in oceanic temperate climate region using much more databases.     

Measurement and Characterization of “Resonance Friction” at High Sliding Speeds in a Model Automotive Wet Clutch

The friction forces between various lubricated “friction materials” and sapphire disks were measured using a new “high-speed” rotating disk attachment to the surface forces apparatus (SFA). Two different clutch lubricants and two different friction materials were tested at sliding speeds and normal loads from 5 to 25 m/s, and 0.2 to 1 N (nominal pressures ~1 MPa), respectively. The results show that “resonance friction”—characterized by large amplitude oscillatory (i.e., sinusoidal) vibrations, also known as shudder or chatter—dominates dynamical considerations at high sliding speed, replacing the smooth sliding or low-amplitude stick–slip that is characteristic of low speed/low load sliding. The characteristic (rotational) speeds or frequencies at which resonance friction occurs depend only on the coupled/uncoupled mechanical resonance frequencies of the loading and friction-sensing mechanisms. In contrast, the intensity of and time to enter/exit shudder depends strongly on the lubricating oil and, to a lesser extent, on the friction material. Physical–chemical analyses of the friction materials before and after testing showed that the samples undergo primarily structural rather than chemical changes. Our results provide new fundamental insights into the resonance friction phenomenon and suggest means for its control.