D. Tech. Mechanical Engineering. / Describes reconfigurable manufacturing (RM) is a paradigm that promises to meet the turbulent demands in current global manufacturing. The major findings of this thesis are as follows; 1. The functional description of the machine tool provides a handy mechanism of aiding COTS machine builders come up with vary configurations of machine tools and their classification from a predefined set of COTS modules. 2. The process of linking the respective part demands to the relevant COTS RMT is a rigorous and tiresome process that demands computational power provided for by the KBS. 3. The subjective linguistic manner of linking the parts and the machine configuration can be managed by including an objective constraint for the fuzzy model. 4. Coupling the decision making using a mathematical model with the use of a KBS brings about the optimum route to arriving to the desired configuration.

British manufacturing Abstraot Companies have been slower to automate their facilities, and computerise their information systems, than many of their overseas competitors in Europe, North America and Japan. Initially, this research studied advanced manufacturing technology, (AMT), systems theory, the UK economy and investigated the underlying reasons for and against company' s decisions to automate. Automating procedures were studied for a sample of 20 Engineering companies with particular attention paid to their; systemic approach to implementing AMT, inter-business activity communications, individual company strategies, operational tactics, and implications from previous installations. This information was supported by questionnaires targeted at UK design engineers' and equipment suppliers. Interviews with Trade Unions, financial institutions, professional institutions and Government, were also arranged. The research found that correctly implemented AMT, with the optimum balance of flexibility and complexity, improved businesses' competitiveness, although many operational efficiencies could be attained merely by rationalising existing systems. When a company implements AMT it is critical that they synchronise the equipment with additional complementary systems and manufacturing resources. However, every company has their own unique solutions due to the historical evolution of factory facilities, product ranges and employee skills. The restrictive practices adopted the financial accountants and many of the Trade Union were found to restrain the rate of implementation for AMT and the move towards total integrated businesses. The research analysis yielded a ten point model for the strategic and tactical management of advanced manufacturing systems. Finally, the work concludes by identifying "accounting systems", and procedures for "designing for manufacture", as areas which deserve further investigation.

The goal of the study presented in this thesis was the improvement of estimation and monitoring procedures for condition monitoring of belt tension and misalignment in belt-driven automated material handling systems widely used in modern semiconductor manufacturing systems. In pursuit of this goal, two 3-factor, 3-level experiments were designed to study how belt vibration characteristics depend on changes in belt length, belt tension, belt misalignment, and initial location of the excitation of belt vibration. Dependent variables in each of the experiments were drawn from a denoised frequency spectrum calculated from an Autoregressive model of the belt vibration time-series. A feature vector was developed from the Autoregressive features via variance based sensitivity analysis. Results showed that belt vibration characteristics were sensitive to changes in all of the independent variables examined. These results motivated the design of a device to improve the standardized technique widely used to monitor belt tension in belt-driven material handling systems. Reducing variance in the belt length and the location of the initial excitation of belt vibration yielded a reduction of tension estimate standard deviation an order of magnitude, as compared to a human performing the standardized technique. Thus, the use of this device provided higher belt tension estimate resolution. Future work that could lead to a less intrusive technique is presented. / text

published_or_final_version / abstract / toc / Industrial and Manufacturing Systems Engineering / Master / Master of Philosophy

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

published_or_final_version / Industrial and Manufacturing Systems Engineering / Master / Master of Philosophy

Τα σύγχρονα συστήματα παραγωγής πρέπει να λειτουργούν αποδοτικά σε ένα δυναμικά μεταβαλλόμενο περιβάλλον. Ένα βασικό χαρακτηριστικό που πρέπει να λάβουν υπόψη τους οι μηχανικοί στη βιομηχανία είναι η ευελιξία των συστημάτων παραγωγής. Η ευελιξία αναφέρεται στην ικανότητα ενός συστήματος παραγωγής να ανταποκρίνεται και να προσαρμόζεται στις αλλαγές του περιβάλλοντος στο οποίο λειτουργεί. Αλλά η ευελιξία είναι δύσκολο να συμπεριληφθεί στη διαδικασία λήψης αποφάσεων κατά τον σχεδιασμό ή τη λειτουργία ενός συστήματος, αν δεν έχει περιγραφεί ποσοτικά. Ο σκοπός αυτής της διατριβής είναι να αναπτύξει και να επιδείξει μια μέθοδο για την εκτίμηση και ποσοτικοποίηση της ευελιξίας. Η μέθοδος μπορεί να χρησιμοποιηθεί σε πραγματικά προβλήματα στη βιομηχανία και να βοηθήση στη λήψη αποφάσεων σχετικά με τον απαραίτητο βαθμό της ευελιξίας που πρέπει να έχει ένα σύστημα παραγωγής ειδικά στην περίπτωση που υπάρχει αβεβαιότητα και είναι δύσκολο να γίνουν αξιόπιστες προβλέψεις σχετικά με τις απαιτήσεις της αγοράς. Στην διεθνή επιστημονική βιβλιογραφία έχουν καταγραφεί αρκετές εργασίες που προσεγγίζουν το πρόβλημα της εκτίμησης της ευελιξίας ενός συστήματος παραγωγής. Οι περισσότερες όμως από τις εργασίες αντιμετωπίζουν μεμονωμένα προβλήματα, κάτω από ειδικές συνθήκες, που τις περισσότερες φορές αναφέρονται και σε συγκεκριμένους τύπους συστημάτων παραγωγής. Η προτεινόμενη μέθοδος στηρίζεται στη θεώρηση ότι η ευελιξία ενός συστήματος παραγωγής καθορίζεται από την ευαισθησία του στις αλλαγές. Όσο λιγότερο ευαίσθητο ένα σύστημα είναι στις αλλαγές του περιβάλλοντος στο οποίο λειτουργεί τόσο περισσότερο ευέλικτο είναι. Η βασική αυτή θεώρηση εφαρμόζεται μέσω της μέτρησης του εύρους των διαφόρων τιμών του συνολικού κόστους ενός συστήματος παραγωγής. Οι τιμές του συνολικού κόστους υπολογίζεται για καθένα σενάριο από ένα μεγάλο αριθμό πιθανών σεναρίων αγοράς. Στη συνέχεια με στατιστική ανάλυση στις τιμές του συνολικού κόστους οδηγούμαστε σε συμπεράσματα για την ευαισθησία ενός συστήματος παραγωγής σε ένα αβέβαιο περιβάλλον λειτουργίας. Ο υπολογισμός του συνολικού κόστους λαμβάνει υπόψη του διάφορες φάσεις του συστήματος παραγωγής στον κύκλο ζωής του όπως την αρχική επένδυση και το κόστος των αλλαγών. Επιπλέον, για να μπορούν οι διαφορετικές τιμές του κόστους να είναι συγκρίσιμες θα πρέπει να υπολογιστούν με βάση κάποιον κανόνα. Η εργασία αυτή προτείνει έναν τρόπο για την εύρεση του ελάχιστου κόστους στον κύκλο ζωής ενός συστήματος παραγωγής. Η προτεινόμενη μέθοδος εφαρμόζεται σε μια περίπτωση μελέτης στην αυτοκινητοβιομηχανία και τέλος περιγράφεται ένα λογισμικό που υλοποιεί την προτεινόμενη μέθοδο καθώς και η UML (Unified Modelling Language) περιγραφή των βασικών οντοτήτων. / Modern manufacturing firms must learn to operate effectively in very dynamic environments. One key aspect that firms must consider is manufacturing flexibility. Manufacturing flexibility refers to the ability of a manufacturing system to accommodate uncertainty in the production environment. But flexibility cannot be considered in the decision making process if it is not assessed in quantifiable terms. The goal of this dissertation is to develop and demonstrate a practical method to assist manufacturers in managing environmental uncertainty and in determining the appropriate level of flexibility in their production systems. A number of research efforts have been published in the litterature that deal with the scientific issue of flexibility assessment. However, most of the published research work deals with case specific engineering problems, under certain circumstances, and in most of the cases they are applicable to specific types of production system. The approach suggested by the this dissertation considers that manufacturing flexibility is determined by its sensitivity to changes. The less flexible a manufacturing system is the more flexible it should be considered. We consider flexibility during the lifecycle of a system, from initial investment to major reconfiguration. A large number of market scenarios are being considered and the lifecycle cost of the system for all scenarios is calculated. Following, statistical analysis on the lifecycle cost results provides results on the sensitivity of the system to the uncertainty of the market environment. Furthermore, in order to make the lifecycle cost values comparable amongst the different production systems, their minimum value is calculated at a minimum level with the help of a specially developed optimization algorithm. The proposed method is applied in a case study in the automotive industry. Finally, a web-based software package that implements the proposed method along with the UML (Unified Modelling Language) description of the main entities is also being described.

A flexible workcell controller has been developed using a three level control hierarchy (workcell, workstation, equipment). The cell controller is automatically generated from a model input by the user. The model consists of three sets of graphs. One set of graphs describes the process plans of the parts produced by the manufacturing system, one set describes movements into, out of and within workstations, and the third set describes movements of parts/transporters between workstations. The controller uses an event driven Petri net to maintain state information and to communicate with lower level controllers. The control logic is contained in an artificial neural network. The Petri net state information is used as the input to the neural net and messages that are Petri net events are output from the neural net. A genetic algorithm was used to search over alternative operation choices to find a "good" solution. The system was fully implemented and several test cases are described.

No description available.

People are unique and display a variety of preferences with regard to the products that are / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, 2007.