| Abstract: |
One of the major challenges for a supervisory controller in a flexiblemanufacturing system is to react quickly to a problem and provide decisions in theshortest possible time using the most accurate and reliable information obtained fromthe shop floor. The response time of the controller depends upon the complexity of thecontrol problem, number of alternative polices considered, and the methodology toarrive at the best decisions, among several others. One of the main key factors that hasnot been extensively considered in the research reported so far is the failure orinterruption of workstations in cellular and functional flexible manufacturing layouts.Workstations breakdowns are an innate feature in any type of shop environment. Thus,it is important to know not only the most preferred repair policy to use whenworkstations fail but also the impact such a policy might have on the performance offunctional and cellular flexible manufacturing layouts. where the crucial affectingparameter on system performance is either the interruption ratio or route index. Thethesis study the problem of machine breakdown in either functional or cellular flexiblelayout together with the different possible dispatching mechanisms. The treatment wasdone taking into consideration two parameters, due date (fixed or variable), andmunber of part types produced (single or multiple), through three models. The firstmodel is a functional layout with fixed due date and single part type, the model havesingle route, double routes, 4 routes, 8 routes, 16 routes, 32 routes, 64 routes, 128routes, and 192 routes. The study of this model investigate the effect of differentinterruption ratios on throughput, makespan, machine utilization, mean tardiness, meanflow time, mean tardiness and mean flow time, and munber of tardy jobs taking intoconsideration the dispatching mechanisms. The results of this model were collectedand analyzed. The second model is functional layout with variable due date and fourpart types, the model have single route, double routes, 4 routes, 8 routes, 16 routes, 32routes, 64 routes, and 96 routes. The study of this model investigate the effect ofdifferent interruption ratios on throughput, makespan, machine utilization, meantardiness, mean flow time, mean tardiness and mean flow time, and number of tardyjobs taking into consideration the dispatching mechanisms. The results of this modelwere collected and analyzed. Two formulae were conducted for that study to correlatethe due date with the interruption ratio and route index. The third model is cellularlayout with variable due date and batch processing, the model have single route,double routes, 4 routes, 8 routes, and 16 routes. The study of this model investigate theeffect of different interruption ratios on throughput, makespan, machine utilization,mean tardiness, mean flow time, mean tardiness and mean flow time, andmanufacturing lead time taking into consideration the dispatching mechanisms. Theresults of this model were collected and analyzed. Several formulae were conducted tocorrelate the due date with the interruption ratio, the route index, manufacturing leadtime and interruption ratio, and manufacturing lead time and rout index. The simulationstudies were done using a ready made software package named by SUv1F ACTOR Y
|
|
|