Mostafa H. Ammar, Stanley B. Gershwin. / "August 1980." Caption title. / Bibliography: leaf 6. / National Science Foundation Grant DAR 78-17826

Lisa Anne Washington, Alexander H. Levis. / "August 1985." / Bibliography: leaf 30.

While some reports on successes of advanced manufacturing technologies (AMT) have been glowing, many companies have tossed millions of dollars worth of fancy equipment into their factories and wound up with little to show for it. It is becoming clear that many of the AMT failures today can be attributed to an inadequate planning process. Proposes a four-stage research framework that addresses issues in: planning the manufacturing system; planning for an appropriate infrastructure; planning for new relationships with the external environment; and justifying investment in AMT. Assesses the strengths and weaknesses of selected contributions in each stage, and identifies gaps in knowledge where research is needed. The framework devised should help tomorrow's research build on the past and increase the research's acceptance by industry, since it draws on both research- and practitioner-based literature along with findings of the field study.

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The purpose of this study was to examine and compare the flexibilities of three apparel production systems to variations in products manufactured on them. The production system used by a company was determined based on five system attributes (i.e., type of workflow, level of WIP inventory, number of tasks, mode of transportation between workstations, and level of interaction between operators). The product line of the company (i.e., staple, semi-staple, fashion, and high-fashion) was determined based on the number and type of collar designs manufactured by the company. Flexibility of a system was determined by the range of collar designs manufactured by the system. A stratified proportionate random sample of manufacturers producing men's and women's shirts and blouses was selected for the survey. The questionnaire was pilot tested for content validity and reliability. The adjusted response rate was 39% (n = 52). Non-parametric tests were performed to test the statistical significance of the hypothesized relationships. Three production systems (i.e., bundle system, progressive bundle system [PBS], and modular system) were compared for their volume of production. The size of the company (i.e., number of employees and the total volume of production) was compared between the three production systems. The five system attributes were found to be significantly related to the system used. The procedure adopted for determining the product line of the company was also found to be significant. The relationship between production systems and product lines was significant in some of the cases and not significant in others. PBS was found to be most flexible due to its ability to accommodate a greater style variation followed by bundle system and modular system. The relationship between production systems and the volume of production and also between the system and the size of the company were not significant. / Master of Science

Thesis (MEng)-- Stellenbosch University, 2014. / ENGLISH ABSTRACT: The South African industry has an increasing need for manufacturing automation. However, the classical form of automation is not cost effective for the low volumes and high variance of products that are produced there. The industry may use the reconfigurable manufacturing system (RMS) concept to improve production of its products. However, industry has been unwilling to adopt the reconfigurable manufacturing systems developed in recent research projects. Due to industry’s hesitance to adopt the control platforms on which reconfigurable manufacturing systems are currently based, the focus of the thesis is on creating a reconfigurable control system using industry accepted technologies. This research focused on evaluating a Beckhoff embedded PC’s suitability as a station controller that controls a reconfigurable subsystem in an RMS. The control system for the station controller was developed using only the IEC 61131-3 programming languages and the Beckhoff programming software. This control system was evaluated by using it to control a station that is responsible for testing a circuit breaker’s tripping current and time. The developed control system was based on the ADACOR architecture because of its optimisation capabilities that were necessary to keep the cycle time of the station as low as possible. The design and implementation of the physical configuration and control system of the station is described in this thesis. The station was designed to meet the requirements of both an RMS and the case study. Because of the limitations of the IEC 61131-3 programming languages, dynamic instantiation of holons is not possible and a method was developed to simulate dynamic task holons. By making use of the embedded PC’s ability to run multiple PLCs at the same time, each type of holon was run in its own PLC thread. The developed control system and station was evaluated by conducting experiments using a laboratory test setup. The evaluation of the developed control system in this thesis proved that an RMS can be created, in the context of station control, using IEC 61131-3 and industry accepted technologies, if a hardware platform is used that allows multiple PLCs to be run in individual threads. The control approach that was created in this thesis can be used to create station control systems that offers optimised cycle times, the benefits of an RMS and the benefits of industry accepted technology. / AFRIKAANSE OPSOMMING: Die Suid-Afrikaanse bedryf het 'n toenemende behoefte aan geoutomatiseerde vervaardiging. Die klassieke vorm van outomatisasie is egter nie koste effektief vir die lae volumes en hoë variansie van produkte wat in Suid Afrika geproduseer word nie. Die bedryf kan moontlik die konsep van 'n herkonfigureerbare vervaardigingstelsel (HVS) gebruik om vervaardiging te outomatiseer. Die bedryf is egter nie bereid om die herkonfigureerbare vervaardigingstelsels wat in onlangse navorsingsprojekte ontwikkel is, te aanvaar nie. As gevolg van die bedryf se huiwering om die beheerplatforms waarop herkonfigureerbare vervaardigingstelsels tans gebaseer word, te aanvaar, is die fokus van die tesis om industrie-aanvaarde tegnologie te gebruik om ‘n herkonfigureerbare beheerstelsel te skep. Hierdie navorsing fokus op die evaluering van 'n “Beckhoff embedded PC” se geskiktheid as 'n stasiebeheerder van 'n herkonfigureerbare substelsel in 'n HVS. Die beheerstelsel vir die stasie beheerder is ontwikkel deur slegs van die IEC 61131-3 programmeringstale en die Beckhoff programmering-sagteware gebruik te maak. Hierdie beheerstelsel is geëvalueer deur dit op die beheer van 'n stasie wat verantwoordelik is vir die toets stroombrekers, toe te pas. Die beheerstelsel was gebaseer op die ADACOR argitektuur as gevolg van die optimeringsvermoëns wat noodsaaklik was om die siklustyd van die stasie so laag as moontlik te hou. Die ontwerp en implementering van die fisiese konfigurasie en beheerstelsel van die stasie word in hierdie tesis beskryf. Die stasie was ontwerp om aan die vereistes van beide 'n HVS en die gevallestudie te voldoen. As gevolg van die beperkings van die IEC 61131-3 programmeringstale, is dinamiese instansiëring van holons nie moontlik nie, en 'n metode is ontwikkelom dinamiese taakholons na te boots. Deur gebruik te maak van die "embedded PC" se vermoë om meervoudige PLCs terselfdetyd te hanteer, kan elke holon tipe in sy eie "thread" loop. Die ontwikkelde stelsel en die stasie is geëvalueer in 'n laboratorium deur middel van eksperimente. Die evaluering van die beheerstelsel in hierdie tesis bewys dat 'n HVS geskep kan word, in die konteks van ‘n stasiebeheerder, deur IEC 61131-3 en tegnologie wat wyd in die industrie aanvaar word, te gebruik mits die hardeware-platform wat gebruik word toelaat dat verskeie PLCs terselfde tyd op een beheerder kan loop. Die beheerbenadering wat geskep is in hierdie tesis kan gebruik word om stasie- beheerstelsels te skep wat optimale siklus tye, die voordele van 'n HVS en die voordele van industrie-aanvaarde tegnologie bied.

published_or_final_version / Industrial and Manufacturing Systems Engineering / Doctoral / Doctor of Philosophy