GMD - German National Research Center for Information Technology, Artificial Intelligence Research Division, Schloss Birlinghoven, 53757 Sankt Augustin, Germany
Costas P. Pappis
Dept. of Industrial Management, University of Piraeus, 185 34 Piraeus, Greece
This paper presents an interactive model based system for the management of production in textile production systems focusing on the Master Production Scheduling problem. Because of the special characteristics of the industry, that is mainly the multi-phase process with multiple units per phase, different planning horizons and different production requirements for each phase, the scheduling of these systems becomes quite complex. Apart from a comprehensive presentation of the set of the modules the system is composed of, together with their interrelationships, the above characteristics are analyzed, and their impact on the production control system is explained. The system is also related to two well-known production control systems, namely MRP-II and Optimised Production Technology. The system’s attributes are presented with the aid of data structure diagrams, while the complete algorithm concerning the Master Production Scheduling module, in a pseudo-code form, and the corresponding part of the database are illustrated in the Appendix.
Keywords: Master Production Scheduling, Decision Support Systems, Production Planning, MRP-II, Textile Industry.
Textile production systems form an interesting area for the study of scheduling problems. The industry has been developed following both vertical integration, particularly among spinning and weaving firms, and horizontal integration, promoted by the idea that a full line of textile products is necessary for effective marketing . Such production systems comprise various
production phases which are illustrated in Figure 1 together with the type of their output. Weaving consists of crossing a yarn, called the weft yarn, with several thousands of yarns composing the warp. Starching is a procedure that comprises synthesis and special treatment of some warps. Warp making is the arrangement of the warp yarns in parallel on a roll. Each yarn is taken from a bobbin which is put on a bobbin stand. This paper describes YFADI, an interactive Decision Support System (DSS) for the management of production in textile production systems. Focusing on a comprehensive description of the Master Production Scheduling (MPS) problem, all related production control processes are presented. The system differs from generic Production Management DSSs, in that it takes into account the special characteristics of the textile industry. These characteristics are discussed below: The textile industry imposes a variety of constraints concerning the integration of an overall scheduling procedure. Typically, a textile production unit is characterized by a multi-phase manufacturing process with multiple production units per phase (i.e., parallel machines). The mixed character of a textile production system, which lies between job-shop and flow-shop, makes production management quite complex. In addition, there are sequence dependent operations, and different planning horizons and production characteristics for each phase. Consequently, different production planning algorithms for each phase are required. For example, the weaving process is characterized by long planning horizons and relatively slow speed of machines, very long setup times, very large production batches, and mixed order and stock-based production. On the contrary, the warp making process is characterized by short planning horizons and high speed of machines, short setup times, small production batches and only orders-based production. The above phases pose the most complex production scheduling problems. Additional special characteristics of the textile industry, that have...