Pacifico Marcello Pelagagge, Gino Cardarelli and Alberto Santalucia
Reports on a comparison by computer simulation between conventional periodic loading (PL) and job‐group loading (JGL). When conventional PL is used, the search of the best part…
Abstract
Reports on a comparison by computer simulation between conventional periodic loading (PL) and job‐group loading (JGL). When conventional PL is used, the search of the best part input sequence must be performed in order to optimize performance of a flexible manufacturing system (FMS). JGL works, instead, as a dynamic rule for real time scheduling of FMS, defining a part releasing policy able to guarantee the reaching of a periodic steady state without non‐productive times on the bottleneck workstation. However, JGL does not assure, in some cases, the same performance arising from the optimal part input sequence of conventional PL, in terms of non‐productive times in FMS filling and emptying phases, work in progress and throughput time. The paper demonstrates that using any JGL rule or the best PL part input sequence gives rise to negligible differences in FMS performance. Furthermore, the dynamic capabilities of the JGL also allow for spontaneously restoring the FMS periodic steady state without non‐productive times after any transient, for instance when production mix changes occur.
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Gino Cardarelli, Pacifico Marcello Pelagagge and Agostino Granito
The principal results of a study concerning the industrial transfer in MOS memory wafer fabrication, of an intrabay material handling system based on a track‐robot are presented…
Abstract
The principal results of a study concerning the industrial transfer in MOS memory wafer fabrication, of an intrabay material handling system based on a track‐robot are presented. A prototype system, installed in L'Aquila University Operations Laboratory, was used in order to verify the congruence of the track‐robot performance within the productive tasks to be carried out. Particular attention was given to the safety systems and the vibrational behaviour of the track‐robot, that strictly influence the aspects that can create risks for a person's safety or the wafer's integrity.
Gino Cardarelli, Mario Palumbo and Pacifico Marcello Pelagagge
Looks at studies into the definition of design and management criteriafor assembly cells with co‐operating robots. Examines task typologiesinto which the assembly process can be…
Abstract
Looks at studies into the definition of design and management criteria for assembly cells with co‐operating robots. Examines task typologies into which the assembly process can be divided and discusses co‐ordination levels and control‐communication architectures. Also looks at the various phases of application development and how it covers many of the same areas of the manual assembly process. Concludes with a consideration of the three main classes of constraints between the actions which different robots have to carry out and states the co‐ordination level that robots have to maintain during constraint‐affected operations depends on these classes.
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Pacifico Marcello Pelagagge and Gino Cardarelli
FMS real time scheduling requires the concurrent solution of both loading and despatching problems. The loading strategy is the most critical and important scheduling decision in…
Abstract
FMS real time scheduling requires the concurrent solution of both loading and despatching problems. The loading strategy is the most critical and important scheduling decision in an FMS. Presents an effective loading rule (job‐group loading rule), based on experimental observations: a group of jobs, reflecting the ratios of the production mix, is loaded on the input warehouse every time that it is completely empty; all the jobs loaded on the input warehouse have to be accessible for the material handling system. Demonstrates how this job‐group loading works as a dynamic rule for real time scheduling of manufacturing systems, defining a part releasing policy able to guarantee reaching a periodic, steady state production. The capability of the job‐group loading rule has been verified when the FMS characteristics are closest to a real situation. Analyses the effects of the interferences on transport operations, the variability of machining times, the finite capacity of interoperational storage and the stops for preventive maintenance or breakdown. Research results show the capability in FMS management of real time scheduling based on the job‐group loading rule.