This paper starts by studying the performance of two inte"elated genetic algorithms (GA) for the static Single Machine Scheduling Problem (SMSP

A Tool Flow System, TFS, is an integral part of a wider system within a Flexible Manufilcturing System, FMS: the Material Flow System. This also includes the Work Flow System.Tool Flow Systems deal essentially with the storage, transport and handling of tools which are exchanged at the machine spindles. Work Flow Systems are particularly concerned with the storage, transport and handling of parts and auxiliary handling devices, such as fixtures and pallets.This article focuses attention on the building blocks ofTFS's and presents a classification, discussion of application and advantages of tool flow fundamental structures. It is argued that the configuration of TFS's and the level of tool replication, may greatly influence the performance and fleXIbility of production in FMS's. Keywords Flexible manufBcturing systems, FMS, tool flow systems, multiple stage systems, MS, combined stage systems, CS and single stage systems, SS. L. M. Camarinha-Matos (ed.), Re-engineering for Sustainable Industrial Production

FMS's do not work well if the required amount of tools to carry out processing, during a given manufacturing period, are not available. High operating efficiency can be ensured, once the right number of tools of each type is available, by conveniently solving the problem of assigning tools and parts to machines. This has been identified as the FMS loading problem (Stecke, 1981). Moreover it is essential that good manufacturing control of part processing priority is realised. In this paper an analytical method is presented for initial assessment of the total number of required tools for efficiently running an FMS. The method is based on tool life duration and on a concept referred to as tool cycle time, as well as on the planned manufacturing period. This is usually taken as the time frame for the solution of the FMS loading problem Two fundamental situations are considered, namely that of static tool loading and dynamic tool loading.. Keywords Flexible manufacturing system. static tool loading, dynamic tool loading.

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