Browsing by Author "Nyanga, Lungile"
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- ItemAnalysis of a time based and corrective maintenance system for a sugar producing company(South African Institute for Industrial Engineering, 2014) Chindondondo, Brian; Nyanga, Lungile; Van der Merwe, Andre Francois; Mupinga, Tapiwa; Mhlanga, SamsonENGLISH ABSTRACT: The Southern Africa sugar producers’ market is under threat from Brazilian sugar, with the latter’s sugar landing in Southern African countries - Zimbabwe in particular – at 75% of the selling price of local producers. This paper outlines an investigation of the current maintenance systems of a Zimbabwean sugar producer and its shortcomings, with a view of optimization. Research has shown that maintenance can contribute between 15 to 75% of production costs, thus playing a critical role in product pricing and consequently competition. Maintenance records and interviews to maintenance personnel from the company were used to extract data relevant to the study. A bottleneck asset in the production line was chosen as a subject to measure the impact of the current maintenance system in cost terms. The study shows that the company is using a hybrid of time based and corrective maintenance. The paper also shows that the current maintenance philosophy resulted in downtime of eighty (80) hours on the subject asset over a four (4) year period, that translated to an equivalent of USD1.9 million in potential revenue lost; which downtime could have been avoided with better maintenance methods. The paper concludes by recommending the introduction of Condition Based Maintenance on the subject asset as an alternative to optimize the maintenance function of the company.
- ItemA decision support system framework for machine selection(South African Institute for Industrial Engineering, 2014) Nyanga, Lungile; Van der Merwe, Andre Francois; Matope, Stephen; Dewa, Mncedisi TrinityENGLISH ABSTRACT: Selecting the right machinery to machine a part is a multi criteria decision making problem which is crucial in production planning. The process becomes more complex and tedious when one has to choose from a variety of machines available in an online registry. This paper investigates this decision making process with the objective to increase machineutilisation for small, medium and micro enterprises. A real time information based decision support system is necessary to assist the decision maker. A decision support system framework for machine selection for a manufacturing agent is proposed based on the Analytical Hierarchy Process (AHP). A human expect uploads parameters for a part that has to be machines. Based on these parameters, suitable machines are sought for from an online machine registry and ranked according to their capability to produce the desired part.
- ItemDesign of cotton ginning dryer control system(South African Institute for Industrial Engineering, 2014) Maradzano, Isabellah; Nyanga, Lungile; Van der Merwe, Andre Francois; Dlodlo, Zwelibanzi B.; Chikowore, Takawira R.; Mhlanga, SamsonENGLISH ABSTRACT: The most important factor in preserving the quality of cotton during ginning is the fibre moisture content. At higher moisture content, cotton fibres are stronger but trash is harder to remove. Selecting ginning moisture content is a compromise between good trash removal and quality preservation. In the paper, inlet and outlet moisture content of cotton being fed into and out of the dryer are monitored at temperatures given in the dryer manual and literature. A mathematical model for drying cotton is then formulated by analysing the experimental results, cotton dryer historical records and dryer manual. The results show that there is a linear relationship between the initial moisture content, final moisture content and drying temperature. A control system integrating a Barionet controller to regulate and supply of heat to the system based on the initial moisture content is then proposed. The objective of the control system is to enable online monitoring of the dryer as well as giving early warning signs when the system is about to get out of control hencesafeguarding from overheating and avoid under-drying of cotton.
- ItemDevelopment of a condition based maintenance system for a sugar producing company(South African Institute for Industrial Engineering, 2014-07) Chindondondo, Brian; Nyanga, Lungile; Van der Merwe, Andre Francois; Mupinga, TapiwaENGLISH ABSTRACT: With globalisation taking centre stage in almost every market; traditionally monopolistic manufacturing companies in Zimbabwe are struggling to compete with international companies whose operations are optimised. This paper focuses on maintenance practises of a Zimbabwean sugar manufacturer with an aim to improve the company’s asset care plans. The company’s current maintenance philosophy and its shortcomings on certain equipment in the plant were identified together with the associated annual maintenance costs. A pareto analysis on the equipment’s breakdown history was used to determine the conditions that can be monitored using Condition Based Maintenance (CBM) and experiments to establish the feasibility of monitoring these conditions were done. A cost benefit analysis of the company’s customary time based and corrective maintenance to a proposed CBM system on the subject equipment was used to show a probable significant reduction in annual maintenance costs should the CBM be implemented. The paper concludes by recommending an implementation matrix for the proposed CBM system with its three main elements of data acquisition, data processing and maintenance decision to introduce an optimised maintenance system that will reduce overall production cost thus bringing an opportunity to compete globally for the local sugar manufacturer.
- ItemEffect of mould temperature on the filling behavior of molten resin in plastic injection moulding of high density polyethylene (HDPE)(South African Institute for Industrial Engineering, 2014) Gwebu, Andile M.; Nyanga, Lungile; Van der Merwe, Andre Francois; Nyadongo, Sipiwe T.; Mhlanga, SamsonENGLISH ABSTRACT: The growth of injection moulding as a manufacturing process has led to the development of more products resulting in an increase in the focus on product quality, as manufacturers try to lower production costs, reduce product weight and eliminate defects. Of particular concern is the flow behavior of molten resin in the mould cavities during the production process. Inconsistencies in the flow of the melt tend to result in uneven or incomplete filling of the mould, resulting in production of defects (short shots). In the paper the Taguchi method is used to determine the optimum values of the injection moulding process parameters for High Density Polyethylene (HDPE.) plastic parts. A moulding processing window in which the process will achieve maximum quality, with major focus being on mould filling is developed.
- ItemRFID Based Automatic Tollgate System (RATS)(South African Institute for Industrial Engineering, 2012) Gunda, Lovemore; Masuka, Lee; Gonye, Reginald; Mhlanga, Samson; Nyanga, LungileRadio Frequency Identification (RFID) is an auto identification technology which uses Radio Frequencies (between 30 kHz and 2.5GHz) to identify objects remotely. The paper describes a system which does the job of detecting, billing and accounting for vehicles as they pass through a tollgate using RFID as the identification technology. In the design, a frequency of 928MHz is used as it is in the Industrial Scientific and Medical (ISM) band. The system is a great investment in the transport industry. It reduces the common hustles in accounting for the movement of goods from point to point. The design can be further developed to aid the satellite surveillance systems once all toll gates are networked. An RFID tag is programmed with information in the form of an Electronic Product Code (EPC), which can be read over a considerable distance so that its contents identify the vehicle and enhance a transaction to be undertaken with respect to the specific tag identity taking advantage of radio frequencies’ ability to travel longer ranges with better data capacities and high speed attained with maximum accuracy. The design has been implemented as a miniaturized prototype.
- ItemTowards the implementation of e-manufacturing : design of an automatic tea drying control system(Southern African Institute for Industrial Engineering, 2014-11) Mabvuu, Never; Nyanga, Lungile; Van der Merwe, Andre F.; Matope, Stephen; Mhlanga, SamsonMany of the production costs for producing tea are attributable to the process of drying the tea. E-manufacturing can assist companies to reduce these production costs by making crucial information available to decision-makers so that they can make informed decisions. This paper presents an application of e-manufacturing to the design of an automatic tea drying control system. This control system will ensure that the multiple drying parameters such as temperature, dryer-exit tea moisture content, and fuel consumption are maintained at optimal states during the course of the drying of tea. The additional aim of this system is to balance the cost of production and the quality of the final product. Using the Guggenheim-Anderson-De Boer (GAB) model, the optimum drying temperature was found to be 100-110°C, while maintaining a dryer-exit tea moisture content of 3 to 3.12 per cent, at a drying rate of 3 per cent per minute. A Barix control application to control the system’s activities, using the web user interface (WUI), was also developed.