Ramez Kian - Nottingham Business School, Nottingham Trent University, Nottingham NG۱ ۴FQ, UK

Purpose: In this paper, an uninterrupted hybrid flow shop scheduling problemis modeled under uncertainty conditions. Due to the uncertainty of processingtime in workshops, which is due to delays in receiving raw materials or machinefailure, fuzzy programming method has been used to control the processingtime parameter. In the proposed model, there are several jobs that must beprocessed by machines in sequence. The main purpose of the proposed modelis to determine the correct sequence of operations and assign operations to eachmachine at each stage, so that the total completion time (Cmax) is minimized.Methodology: In this paper, the fuzzy programming method is used to controlthe uncertain parameter. Also, The GAMS software and CPLEX solver havealso been used to solve the sample problems.Findings: The results of solving the problem in small and medium size showthat with increasing the rate of uncertainty, the amount of processing timeincreases and therefore the completion time of the whole work increases. Onthe other hand, with the increase in the number of machines in each stage dueto the high efficiency of the machines, the completion time of all works hasdecreased.Originality/Value: The most important innovation of this article is the designof uninterrupted hybrid flow shop scheduling with regard to the fuzzyprocessing time.

Hybrid Flow shop Scheduling, Uncertainty, Fuzzy Planning Method