Thesis (MScEng)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Reconfigurable Manufacturing Systems (RMSs) have the ability to
reconfigure hardware and control resources at all of the functional and
organizational levels. This allows for quick adjustment of production
capacity and functionality in response to sudden changes in market
or in regulatory requirements.
This study evaluates the characteristics and operation of automated
reconfigurable assembly lines using discrete event simulation. The assembly
line uses a conveyor system which transports pallets to various
machines to perform the assembly process. Different conveyor configurations
are developed for the same assembly process using Simio
simulation software. A part family consisting of five variants are
assembled on the same assembly line with a large variation in the
production quantities for each product. This requires the assembly
system to be able to quickly adjust its functionality and capacity.
Multi-objective optimization is performed on the models through the
use of a Pareto exhaustive search experiment. The two contradicting
objectives used are the throughput rate of the system and the average
work in progress, with the aim of maximizing the former and minimizing
the latter. From the Pareto exhaustive search experiment, a
Pareto front is constructed showing which configuration is preferred
under certain operation conditions. However it is concluded that the
Pareto front can be tailored to fit the specific needs of the decision
maker, depending on what the decision maker is willing to pay.
An experiment that evaluates the effect of changing the conveyor
speed is performed. It is established that under certain operating
conditions, increasing the conveyor speed higher than the ceiling value
will not improve the performance of the system. A production scenario was also developed which include different order
sizes for each of the five parts of the part family. The configurations
have to alter their capacities based on the order sizes to test which
system performs the best under these operating conditions. For this
experiment, the ramp-up time was of interest but the best system was
chosen based on the combination of throughput rate and the average
work in progress.
From the results of the different experiments, it is recommended to
first determine the maximum capacity and the operating logic before
choosing one of the configurations. Once this is decided, the
information gathered from the experiments can then be tailored for
the decision maker to establish the best operating conditions for the
chosen con guration. The developed simulation models are used as a
Decision Support System for future research on the topic. It is recommended
for future research to focus on using Automated Guided Vehicles
(AGVs) instead of a conveyor system as transportation method. / AFRIKAANSE OPSOMMING: Herkonfigureerbare Vervaardigingstelsels (HVSs) het die vermoee om
alle hardeware en beheer hulpbronne, op alle funksionele en organisatoriese
vlakke te herkonfigureer. Dit maak dit moontlik vir vinnige
verstellings aan produksie kapasiteit en funksionaliteit, indien daar 'n
skielike verandering in die mark of wetgewing is.
Hierdie studie evalueer die karakteristieke en werking van outomatiese
herkon gureerbare monteerlyne met behulp van diskrete gebeurtenis
simulasie. Die monteerlyne gebruik vervoerbande om pallette na
verskeie masjiene te vervoer, sodat die parte aanmekaar gesit kan
word. Simio simulasie sagteware is gebruik om verskillende vervoerband
kon gurasies vir dieselfde monteringsproses te ontwikkel. 'n Part
familie van vyf variante word op dieselfde monteerlyn aanmekaargesit.
Daar is 'n groot variasie in die produksie hoeveelhede van elk van
die vyf variante, dus moet die monteerlyne vinnig die kapasiteit en
funksionaliteit kan aanpas.
Multi-doelwitoptimering is toegepas op die modelle deur 'n Pareto
alomvattende soek eksperiment uit te voer. Die twee teenstrydige
doelwitte wat gebruik is, is die deurset tempo van die stelsel asook
die gemiddelde werk-in-proses. Die doel is om die deurset tempo te
maksimeer en terselfde tyd die gemiddelde werk-in-proses te minimeer.
Die Pareto alomvattende soek eksperiment word verder gebruik om
'n Pareto front te skep wat uitwys watter vervoerband kon gurasies
verkies word onder sekere bedryfstoestande. Die Pareto front kan
egter aangepas word om die spesi eke behoeftes van die besluitnemer
te pas.
'n Eksperiment is uitgevoer om die uitwerking van die vervoerbandspoed
op die stelsel te toets. Resultate het getoon dat onder sekere bedryfstoestande die werkverrigting van die stelsel nie verbeter indien
die spoed 'n maksimum grenswaarde oorskry nie.
'n Eksperiment wat 'n produksie scenario voorstel is ontwikkel waarin
die vraag na die vyf part variante gevarieer word. Die vervoerband
konfigurasies moet dan die kapasiteit aanpas gebaseer op die vraag
na die parte. Die doel van die eksperiment is om te toets watter
kon gurasie die beste vaar onder hierdie bedryfstoestande. Die tyd
wat dit neem vir die stelsel om weer op dreef te kom na 'n verandering
in kapasiteit is ondersoek in hierdie eksperiment, maar die beste stelsel
is nog steeds gekies gebaseer op die kombinasie van deurset tempo en
die gemiddelde werk-in-proses.
Gegewe die resultate van die verskillende eksperimente, word dit voorgestel
dat die besluitnemer eers die maksimum kapasiteit en die bedryfstoestande
vasstel, voordat 'n vervoerband kon gurasie gekies word.
Sodra dit besluit is, kan die inligting wat tydens die eksperimente ingesamel
is, aangepas word om die beste bedryfstoestande vir die kon gurasie
wat gekies is, vas te stel. Die simulasie modelle wat ontwikkel is
word gebruik as 'n besluitnemingsondersteuningstelsel vir toekomstige
navorsing oor die onderwerp. Dit word voorgestel dat toekomstige
navorsing die moontlikheid van geoutomatiseerde begeleide voertuie
(GBV), in plaas van vervoerbande as vervoermiddel, ondersoek.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/17906 |
| Date | 12 1900 |
| Creators | Du Preez, Jacques |
| Contributors | Bekker, J., Stellenboch University. Faculty of Engineering. Dept. of Industrial Engineering. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 123 p. : ill. |
| Rights | Stellenbosch University |
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