0000000000388006
AUTHOR
S. Noto La Diega
A Simultaneous Approach for IMS Design: a Possibility Based Approach
IMS investments are characterised by high fixed costs and long life cycles. On the other hand, their redditivity and risk coverage depend on their manufacturing efficiency that is mainly defined during the design phase by fixing the system configuration. Due to the flexibility required to IMS, system configuration depends not only from technological information, such as product routing table and service times, but also from marketing data such as the typology of products to be manufacture and their production volumes. Moreover, the evaluation of the redditivity and the risk of the investment depends on market information such as product prices as well. Such interdependencies make the invest…
Interdependence Between Tool Fracture and Wear
Wear and fracture are the main causes of tool scrapping. However fracture plays a major role for increasing values of the hardness and brittleness of tool materials or when low-cobalt tungsten carbides are used or in interrupted cutting conditions where it is the most relevant factor for tool scrapping. In order to obtain the optimal values of the cutting speed both these factors should be considered. The hypothesis of stochastic independence among them simplifies the mathematical formulation of the optimization problem; but experimental investigations do not agree with this assumption and, as a matter of fact, the probability density function of tool fracture results to be dependent on the…
Multiobjectives Approach for Process Plan Selection in IMS Environment
Abstract In Integrated Manufacturing Systems (IMS) evaluating the most suitable process plan is a very complex task. Technology, quality, production and market requirements are objectives to be pursued in the selection process, subject to the constraints due to the several part types simultaneously manufactured. The paper proposes a new approach to the process planning selection, based on a possibilistic fuzzy programming model in order to face the vagueness coming from the formalization of the objectives and constraints in the selection problem.
Production planning in reconfigurable enterprises and reconfigurable production systems
Reconfigurable enterprises and reconfigurable production systems represent nowadays one of the key responses towards the organisational and manufacturing needs arising in the new era known as mass customization. The paper proposes an Agent Based approach for the production planning activities in reconfigurable enterprises, characterized by complex, articulated and geographically distributed production capacities contended by many product families and composed by reconfigurable production systems that allow quick adjustment of production capacity and functionality consenting to manufacture different products of the same part family.
High Level Planning of Reconfigurable Enterprises: a Game Theoretic Approach
Reconfigurable Enterprises (REs) represent production networks made of different and geographically dispersed plants that, in case of unpredictable market changes, can be reconfigured in order to gather a specific production objective. However, REs effectiveness and efficiency depend on the extent to which global performance is obtained. Basically two approaches are available to reach coordination: centralised or decentralised planning tools. In this paper, the authors propose a novel cooperative game theoretical approach for distributed production planning at high level of a RE; the proposed approach has been benchmarked in front of both a distributed one, based on negotiation, and a centr…
On Line Tool Life Prediction for Tool Replacement Strategy in FMS Workstation
In FMS environment a large variety of tools are shared resources being employed to process different part type varying the cutting parameters during their useful life. The paper suggests a new methodology to predict the tool life on line using the information deriving from the control station of the production system to gain information about the tool wear.
A RELIABILITY MODEL FOR OPTIMAL ALLOCATION OF SPARE TOOLS IN FMS
ABSTRACT A model for the dynamic management of the tool set of an FMS workstation is developed. The proposed approach processing the on-line recorded tool failure data updates the estimate of the parameters of the probability density functions of tool life and selects, at the occurence of each failure, the code of the tool to be allocated in the workstation storage devices in order to maximize its reliability over a planned horizon.
Negotiation mechanisms for capacity allocation in distributed enterprises
Abstract The paper proposes an agent based approach for the capacity allocation in distributed enterprises, characterized by complex and articulated organizations and by geographically distributed production capacities contended by many product families. In such a scenario the process of allocating the production capacity to the single customer order is one the major bottlenecks of the production planning activity as far as many organizational decisional levels are involved and market turbulence implies a continuous retuning of the capacity allocation plan. A high grade of reactiveness is needed. Agent based approaches and negotiation models, by decentralizing the decisional control and sim…
Lower and Upper Bounds of Manufacturing Cost in FMS
Abstract The use of traditional techniques of product costing, cost control and performance evaluation in advanced manufacturing environment supplies poor results to operations management. In this paper, after a brief review of the major drawbacks of traditional machining economics, a new framework for product costing will be presented. The basis of the proposed approach lies on an analysis of the production process aimed at single out proper cost drivers for the use of the various employed manufacturing resources. As a consequence, the quota of the manufacturing cost of uncertain allocation is drastically reduced. A lower and an upper bound value of the unit production cost are also define…
Cost Analysis of FMS Throughput
Abstract The need for an effective cost planning and control system is stressed in today highly competitive manufacturing environment. The conventional approaches of machining economics to cost analysis are no more able to cope with the new structure of the production costs in the highly automated - highly integrated manufacturing systems. Suitable cost analysis procedures should provide a strong integration between process planning data and overall system performances. The here proposed procedure for the estimate of the unit manufacturing cost in FMSs achieves this integration by using performance evaluation techniques like discrete event simulation or queueing network models.
Machining Economics in FMS by a Fuzzy Approach
Abstract In a conventional manufacturing system, cutting parameters have to be fixed in order to pursue the economical and productive target related to each cutting operation. In a Flexible Manufacturing System (FMS), as a consequence of the unbalanced workload due to the mutual interaction among the shared resources, the optimization of each operation does not allow the optimum of the global production system to be reached. A fuzzy programming model is developed in this paper in order to select cutting speeds of the operations in the production plan as a satisfying compromise solution between single operation and the integrated system targets.
A Fuzzy Discrete Event Simulator for Fuzzy Production Environment Analysis
Abstract Discrete Event Simulation is a powerful tool to help production managers in planning manufacturing systems. The necessity to rapid react to market conditions is pushing production planners to process requirements and information affected by vagueness. Vagueness is related with event definition, therefore it is not manageable through statistical tools, but more properly by using fuzzy mathematics. Production situations where uncertainty takes body in term of vagueness are referred as Fuzzy Production Environments. Classical Discrete Event simulators are not suitable to deal with fuzzy variables, therefore they cannot be used to model Fuzzy Production Environments. This paper aims to…
Coordination policies to support decision making in distributed production planning
Abstract Distributed production networks are considered organizational structures able to match agility and efficiency necessary to compete in the global market. Performances of such organization structures heavily depend on the ability of the network actors of coordinating their activities. The research proposes to model and design coordination problems within production network by using the Multiple Agent Technology. In particular, the paper proposes new strategies for coordinating production-planning activities within production networks. Such models have been developed and tested by using a proper simulation environment developed by using open source code and architecture. The results o…
A Reference Scenario for IMS Strategic Design
Today is fully acknowledged that manufacturing is a formidable competitive weapon. The strength of such a weapon is essentially defined during the first step of the design phase called strategic design. During this phase, in fact, the principal characteristics of the manufacturing systems are to be defined taking into account the competitive environment and the competition strategy. Classical analytical models for IMS design often neglect this aspect and, perhaps, this is one of the causes of IMS failure. The paper proposes a set of analytical models for strategic IMS design; they have been classified into four classes, each one pursuing a determined set of objectives, providing, in this wa…
Fuzzy methods for analysing fuzzy production environment
Abstract Very recently, in production management research literature, the necessity to extend production systems analysis techniques, such as queue theory, Mean Value Analysis (MVA) and discrete simulation, to Fuzzy Production Environments, i.e. to those production situations in which data are vague, has emerged. Fuzzy set theory is a powerful tool to model vagueness and, therefore, fuzzy mathematics can be used to extend classical production system analysis techniques. This paper proposes a methodology based on fuzzy relation algebra to extend classical MVA and discrete event simulation.
A Decision Making Tool in FMS Design
In FMS design one of the initial fundamental decision concerns the flexibility level of the workstations to be implemented. New machining centers offer the possibility to carry out several operations on the workpieces to be processed, thus reducing the workload both of the material handling system and of the resources used to control the part flow in the FMS. In spite of advantages related to the use of the machining centers with high flexibility, the better typology of each workstation must be evaluated taking into account its influence on the tools fleet and on the workload of the handling and tool room subsystems.
Business Process-oriented design of Enterprise Resource Planning (ERP) systems for small and medium enterprises
In the last few years, many organizations have used business process modelling as an effective tool for managing organizational changes. However, process modelling has rarely been exploited for supporting the entire business process management life cycle. This includes the design of business processes as well as their implementation and control. The adoption and implementation of Enterprise Resource Planning (ERP) systems is a crucial issue if referred to small and medium-sized enterprises. The main problem is that the cost of implementation of ERP, intended as the process of customization of the ERP system towards the actual enterprise business processes, overtakes the cost of ERP acquisit…
Fuzzy Discrete Event Simulation for Fuzzy Production Systems Analysis
Abstract Fuzzy production systems are characterised by vagueness in data and requirements that very often cannot be reduced to stochastic models. Therefore, such production systems cannot be analysed by using classical techniques such as Queue Theory or Discrete Simulation Analysis. On the other hand the great diffusion of Fuzzy Production environments in small and medium enterprises claims for the development of new analysis tools. This paper proposes a new approach to Discrete Event Simulation able to treat with fuzzy variables. A new methodology has been proposed to process fuzzy information within discrete event simulation and a prototype of a Fuzzy Discrete Event Simulator has been dev…