Thesis (MBA)--Stellenbosch University, 2001. / Some digitised pages may appear illegible due to the condition of the original hard copy / ENGLISH ABSTRACT: The decision to make equipment replacements has a major influence on the competitiveness of any business. A company like Iscor recently spent approximately one billion Rand to modernise its fleet of equipment at various centres. This report presents a holistic approach to the issue of equipment replacement decision-making. It contends that equipment replacement decisions are not isolated incidents that occur by chance. In fact, the whole process is an integral part of the various processes in the business. This ranges from the influence on the strategy, through to issues such as production planning, maintenance, staffing, financial planning and so on. The role of the replacement decision in each of these elements are discussed and elaborated on. The report goes on to review the various models available in the industry and discusses their advantages and disadvantages. Thus ensuring a clear understanding of the differences in the approaches. The report attempted to propose a method that is relatively straight forward and in terms of application lends itself to the practical mining man. The proposed models are then used to complete a relatively simple example. The example was primarily aimed at showing the elements of the application and certainly not the full extent of the model. / AFRIKAANSE OPSOMMING: Die uitvoer van toerusting vervanging_sbesluite kan 'n dramatiese invloed op die mededingendheid van enige besigheid hê. 'n Maatskappy soos Iscor het onlangs 'n bedrag van ongeveer een biljoen Rand gespandeer om hul vloot van toerusting op verskeie sentrums te vervang. Die verslag stel 'n alles omvattende benadering tot die kwessie van toerusting vervangingsbesluitneming voor. Die verslag gaan voort om voor te stel dat die vervangingsbesluit nie iets is wat toevallig geneem moet word nie. Inteendeel dit is 'n integrale deel van al die verskeidenheid besigheidsprosesse. Die verslag bespreek die verskeidenheid modelle beskikbaar en brei uit oor die voor - en- nadele van elk. Die bespreking verseker dat die leser 'n duidelike beeld kry oor die toepaslikheid van die verskeie modelle. Dit gaan voort om 'n praktiese model voor te stel wat redelik maklik is om aan te wend. Die model word dan toegepas op 'n eenvoudige voorbeeld.

published_or_final_version / Industrial Engineering / Master / Master of Philosophy

No description available.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 86-91). Also available on the Internet.

Mémoire (M.E.S.R)-- Université du Québec à Chicoutimi, 1992. / Résumé disponible sur Internet. CaQCU Document électronique également accessible en format PDF. CaQCU

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references (leaves 86-91). Also available on the Internet.

M.Phil. / In an ever - increasing competitive business world it is essential to optimise the replacement of expensive mining equipment. The decisions regarding the replacement of assets used in a coal mine are usually based on life cycle costing models. Financial methods such as Net Present Value, Internal Rate of Return or Payback are applied to determine the feasibility of replacement of the asset. Whereas these methods and other models such as life cycle costing, challenger / defender and the Non-Homogeneous Poisson Process models can be applied in most cases, it is deemed to be insufficient as the sole decision making tool for the replacement of mining equipment. The development of another tool to assist in the decision making process is required for specific use by the engineer to be used in conjunction with the traditional financial models. Key performance indicators are used extensively in the mining industry to manage the performance of equipment and are deemed to be essential components in achieving the organisation's objectives. There are certain limitations when using only the traditional financial life cycle costing methods when viewed from the engineer's perspective, since they do not directly incorporate the level of the maintenance function and the performance effectiveness of the asset. The engineer usually requires more insight into the performance of the asset to assess the feasibility of replacement, hence the need for an additional tool that incorporates these key performance indicators. In most cases there are relationships between the various key performance indicators themselves as well as between them and the operating and maintenance cost of the asset. The key performance indicators used are availability, reliability (mean time to failure), maintainability (mean time to repair) and the operability (tons per direct operating hour). There are certain factors that may lead to the excessive operating and maintenance cost of an asset, especially if there is no investigation into the reasons for the excessive cost. Examples are sub-standard maintenance practices and an insufficient level of service from suppliers. Both are issues that can be resolved with a consequent decrease in the cost of ownership of the asset. Cost as the only indicator of the feasibility of replacement may therefore not be a true reflection of the real status of the performance of the asset. Weighting factors are used to allocate values to the key performance indicators in terms of their contribution towards achieving the organisational objectives. The equipment effectiveness is derived from these values to give an indication of how well the equipment is performing against predetermined benchmarks. This dissertation attempts tb find a solution to the problem through the use of the key performance indicators in addition to the existing models that focus on the financial aspect in order to provide a more accurate assessment of the replacement requirement of an asset in an opencast coal mine.

Often, in both the military and industrial sectors, the unavailability of essential components renders a complex system inoperable. Therefore, the primary objective of this research is to develop a methodology for determination of feasible strategies for the repair/replace decision. In the general equipment replacement problem, a finite planning horizon may be partitioned into stages such that an end item deteriorates toward a final stage where it is no longer economically or operationally feasible to continue to repair the item, or the item experiences fatal failure. This multi-stage deterioration process is very amenable to a dynamic programming solution methodology where the output from one stage becomes the input to the next stage. In the multi-stream replacement problem, the population of end items is grouped into streams depending upon such parameters as item age, the number of operational hours, or the environment in which the item operates. The reliability function is used to describe the survivor probability in this population model. A dynamic repair/replace program is formulated where the state functions are characterized by two parameters - item age and current operational condition. A computerized model is then developed that facilitates evaluation of repair/replacement strategies with respect to total life cycle costs of a logistics system. The solution methodology accommodates both stochastic and/or deterministic demand; different hazard models; a budget constraint; repair capacity constraint; various levels of repair; technological improvement; and organizational implementation issues. The operations impact of a generalized methodology for supporting the repair/replace decision and mode of repair is to provide opportunities for a more efficient use of organizational resources such as capital and repair facilities. / Ph. D. / incomplete_metadata

This study can be classified under the subject of equipment item replacement analysis. Simultaneous failure, SF, of the components of an equipment item, EI, is the topic of this thesis. Examination of the possibility of designing components of an EI for SF is one objective of the study. The motive for this objective is the belief that SF designs of EI minimize the total cost of acquiring and operating the EI. Examination of the strength of materials reveals that design life of components is not sufficiently flexible to realize SF, and design requirements can predetermine design life. This is true for mechanical components such as links, gears, and bearings. Hence it was concluded that SF of the mechanical components of an EI, cannot be easily achieved. The second objective of the study was to formulate a model for optimizing the design of the components of an EI with life considerations. A mechanical reliability model was first modified by the inclusion of fatigue stress-strength relationships, and the theory of Cumulative Damage. By mathematical manipulation to suit the principles of Lagrange's Method of Undetermined Multipliers, an optimization model has been developed. This model enables system and component design constraints and requirements to be included in the optimization process. / Master of Science