برنامه ریزی تولید تعاونی برای شرکت های کوچک و متوسط

Minimising manufacturing cost and production time parallel to raising the quality and the shipment reliability are important challenges in every production system. In case of distributed production systems the management of the above-mentioned criteria has great significance and needs a complex, co-operative handling of the problems. A new, co-operative manufacturing network model is proposed for co-ordinating the production of Small- and Medium-sized Enterprises (SMEs), based on the holonic paradigm. The paper introduces the main modules of the model succinctly and describes an application under realisation in Hungary, in an agricultural SME network, pointing its economic benefits as well.

On the present level of market competition, enterprises have to organise themselves into effective production system architectures in order to be able to fulfil the market demands. These system architectures can be realised only by using computer networks for production management in order to co-ordinate the production of the distributed manufacturing units. There are different approaches, different names (agile, biological, fractal [1], holonic, etc.) for production-, or manufacturing systems that basically cover the same idea: a flexible network of co-operating autonomous manufacturing units. The holonic manufacturing system is an approach for a theoretical framework for autonomous and decentralised manufacturing organisations based on the classical holonic theory introduced by Koestler [2]. The holonic production system is a system of co-operating holons that are organised to achieve a production goal. This system integrates the whole range of activities from booking the orders through design, production and marketing to form an autonomous and decentralised production organisation. According to the holonic organisation paradigm the manufacturing environment is going to transform itself into a holonic system as openness, flexibility and similarity in building blocks are vital advantages. The virtual enterprise is a practical instantiation of the holonic paradigm in the form of a multilayer, open, flexible (through continuous, dynamic re-configuration) network. The structure of a virtual enterprise can be seen as a holarchy, i.e. it is a temporary, goal-oriented aggregation of several individual enterprises. Each virtual enterprise is created to pursue a specific business objective, and remains in life as long as this objective can be pursued. After that, the individual nodes resume their independence from each other. The resource of a node that was previously allocated to the expired business is re-directed toward the node's individual goals, or toward other virtual enterprises. The original virtual enterprise (VE) model has been developed for decomposing large companies that have enough financial, human and organisational resources. The decomposition is based on functions that can result in replications across the network. In the Planning Small–Medium Enterprise Networks (PLENT) project (ESPRIT Project No. 20723) a more practical, more appropriate approach of the virtual enterprise has to be realised for Small- and Medium-sized Enterprises (SMEs). For the customers the network reflects the framework of a big company, a big economical organisation which can provide complex products associated with bigger capital and professional knowledge, while the basic functions of the SME that are important for their independence remain intact. In such a distributed manufacturing environment the production planning has a key role. The co-ordination of the orders, the optimal assignment of the different resources in a co-operative production of several SMEs is a very difficult task. The SME network development work is done in the framework of the PLENT project with the participation of firms from Italy, Greece, Hungary and Spain. The main goal of the project is to support organisations that manufacture mechanical parts and products in SME-like production environments. The paper introduces this management philosophy and the network model briefly then describes a special application of the manufacturing network model for agriculture production (oil and seed production).

In the PLENT approach, which is a practical modification of the original holonic paradigm for SMEs, the network is conceived as a set of operational nodes (SMEs) with equal rights, co-ordinated by a central unit that interacts with customers, distributes tasks to nodes on the basis of prefixed criteria and up-to-date information on node state and reliability. This central unit informs each node on its position in the network with respect to the manufacturing process and also tries to solve possible network perturbations. The nodes are responsible for executing the assigned tasks within given time intervals and, to this purpose, they maintain direct relations with the respective suppliers and clients. This new approach for SME network co-ordination is very promising, because it offers the advantages of the holonic manufacturing paradigm giving the possibility, in parallel, of keeping the traditional individualism of SMEs. The realisation of the method is progressing in four countries involving SMEs from three different fields of production (in machine- and textile industry and in agriculture). The experiences of the pilot realisations show that significant financial benefits can be gained as well. The results achieved prove that it is possible to develop a network-based co-ordination software for SMEs that is general enough to be applied in fully different production fields even in the very unpredictable field of agriculture.