Industrial and Manufacturing Engineering Publications

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Performance analysis of immigration operation by discrete event modelling and simulation
(2009) Gandure, J.; Mhlanga, S.
Discrete event modelling and simulation were used to analyse the performance of immigration operation in Botswana. The relationships between length of queues of immigrants, queuing time, service time and engagement of duty officer were investigated. Data collected by direct observation and clock-timing of processing immigrant request at an inland office on a normal working day was used to determine whether to increase or reduce the number of serving officers to balance the operations. The findings indicated that the system of operation was balanced or fairly matched by 75 % utilization of the officer, average immigrant queuing time of 4.2 min, and required no changes. The pilot study could be replicated at other boarder posts and airports prior to the expected influx of tourists during the 2010 World Cup Football Competition in South Africa.
Air pollution control techniques for the cement manufacturing industry: A case study for Zimbabbwe
(2012) Zimwara, D.; Mugwagwa, L.; Chikowore, T.R.
Technological advancement has resulted in cement making companies being able to produce higher volumes compared to the past. However the higher production levels have also been largely labelled as the leading cause of pollution. The main sources of air pollution in the industry include excavation activities, dumps, tips, conveyer belts, crushing mills and kiln emissions. Harnessing appropriate technology for use in the cement industry could go a long way towards minimising on-site wastes and pollution. This review examines various options in practice for reducing pollution at cement manufacturing companies, which help ensure legislative compliance. By adoption of appropriate technology and computer modelling, industry will not only reduce production waste but also comply with legislation to do with environmental protection. The paper examines certain methods of pollution control used for air and looks at how computer modelling can be adopted for the classification, quantification and control of particulate matter; and how efficient energy use can contribute to better air quality. An analysis of gas stack emissions was done for a cement manufacturing company in Zimbabwe where compliance was investigated. Emissions samples were randomly selected at various points within the company and concentration of various emission constituents were analysed.
Cost of Quality as a Driver for Continuous Improvement - Case Study – Company X
(2013) Zimwara, D.; Mugwagwa, L.; Maringa, D.; Mnkandla, A.; Mugwagwa, L.; Ngwarati, T.T.
In the manufacturing, metal casting industry is one of the oldest basic principal and most important industries. The casting process is hindered by the occurrence of various defects. High casting reject levels and customer returns have a considerable adverse effect on productivity, delivery performance, customer satisfaction and employee morale. In addition excessive rejection reduces yield, wastes valuable raw materials and involves management time in problem solving. All foundry processes generate a certain level of rejection that is closely related to the type of casting, the processes used and the equipment available. This paper seeks to establish the extent to which cost of quality can impact on continuous improvement of the products and the relationship with the customers of the organization. To determine the cost of quality (COQ) at casting company X, the researchers used existing company records, publications and historical evidence of the company. The researchers utilized techniques such as, bar charts and tables in presenting and interpreting data. The above techniques have the ability to provide methods for collecting, presenting, and analysis and meaningfully interpret data. The research findings estimated the COQ to be 6.6% of sales revenue.
Soft Computing Methods for Predicting Environmental Quality: A Case Study of the Zimbabwe Sugar Processing Industry
(2013) Zimwara, D.; Mugwagwa, L.; Nherera, K.
Sugarcane growing and processing is associated with environmental degradation and pollution. The impact that sugar processing industries have on the environment affects the ecosystem. Methods of soft computing that is fuzzy logic, neural networks, and genetic algorithms can be adopted for environmental protection, particularly in the developing countries. Soft computing techniques, particularly neural networks and fuzzy logic, have been used to predict and sometimes control air quality. This paper looks at how fuzzy logic can be adopted for predicting air quality. The common environmental impacts associated with sugarcane production are water and air pollution. This paper focuses on air pollution. The major waste streams are identified and the extent of air pollution is predicted by classifying the air quality as poor, ordinary, very good, and excellent. This paper presents a fuzzy rule base that can be used to classify the pollutants and predict the air quality based on the amount of the specific pollutant in the air. The Mamdani fuzzy inference system is used to build the rule base, with the membership functions being non-intersecting and triangular. The adoption of fuzzy logic techniques will help sugar processing industries to be aware of the impact their operations have on the environment.
Academic staff development strategies in engineering fields of study: case study of Zimbabwe
(2013-06) Mhlanga, Samson; Matope, Stephen; Mugwagwa, Lameck; Phuthi, Nduduzo; Moyo, Vincent S.
Higher education is the basic instrument of economic growth and technological advancement in any society. The economic meltdown in Zimbabwe which climaxed 2008 with an inflation level of 231million % exacerbated the brain drain. After the economic meltdown, Zimbabwe is in the process of rebuilding the quality of staff and the staffing levels in its higher education institutions. The challenge has been the decision on the mode of study: whether to go via taught masters or masters by research; where to allow the faculty members to study: in the region, or beyond; on a fulltime or on a part-time basis or on a split-site basis. These challenges have been due to the need to have a quick but quality programme of staff development, while maximising on the resources available for staff development. A survey was undertaken of the engineering related departments in Zimbabwe universities focusing on the existing staffing levels, their qualifications, current numbers undergoing study and their levels. The challenges faced by each institution from the administrative side and from the staff side are summarised. Recommendations on staff development strategies are given in conclusion.
INVESTIGATION OF THE EFFECTS OF LUBRICANT FAT CONTENT ON DRAWN COPPER WIRES
(2013-07) Chiduwa,A.C.; Nyanga, L.; Mhlanga, S.; van der Merwe, A.F.; Kanyemba, G.
The Lean Manufacturing goal of reducing waste and increasing productivity has made it a necessity to produce good quality products in manufacturing industries at a low cost. In the cable manufacturing companies this can be achieved by optimising the wire drawing process. One way to meet the desired quality of the drawn wires is to improve lubricant efficiency through installation of an automatic, continuous lubricant fat content control system on the drawing machine. The paper shows a method of finding the optimum lubricant concentration for producing good quality copper wires using Taguchi experiments. Taguchi experiments are employed to analyse the effects of different lubricant fat content levels on the tensile strength and lubricant temperature. The results from the experiments indicated that the tensile strength of the wire is affected by low lubricant fat content. The lower the lubricant fat content: the lower the tensile strength drawing lubricant resulting in numerous wire breakages that affect the quality of the final product, namely the cable
Development of a condition based maintenance system for a sugar producing company
(2014-07-14) Chindondondo, B.; Nyanga, L.; Merwe, A. V.; Mupinga, T.; Mhlanga, S.
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. The paper then recommends and proposes a CBM system replete with its three main elements of data acquisition, data processing and maintenance decision making to reduce breakdowns on the subject equipment by at most 76%.

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