Process mapping, modelling and optimization of plant layouts and materials handling in manufacturing

Abstract: Documenting process flows in a manufacturing environment provides a guide to understanding how processes are interconnected and how materials are handled, thus forming the basis for modelling and optimization in order to simplify the otherwise complex systems particularly in multi-product manufacturing. Research was carried out at a furniture manufacturing company specializing in the production of a wide range of furniture from hardwood. Owing to the multiplicity of processes and the movement of materials in manufacturing environments, the factors affecting such setups increasingly become complex, equally requiring complex techniques to analyze and optimize them. A work study carried out at the company established inherent problems that affected production and were used as the basis for modelling and optimizing the processes, focusing on grouping of workstations depending on functions, predicting performance using simulation and machine distance matrices for a reorganized plant layout. Results obtained after modelling and optimizing the plant layout were useful for production planning and control as well as enhancing the company’s productivity and efficiency

Reinforcement of synthetic rubber with carbon nanoballs to produce nanocomposite ion exchange membrane

The improvement of the mechanical properties of emulsified styrene butadiene rubber ion exchange membrane through blending with 60nm carbon nanoballs is reported in this work. Homogeneous blending was achieved using a 200W Probe Ultrasonicator at 60% amplitude to produce a 160μm thick nanocomposite ion exchange membrane. Weight concentrations varying from 0.25 to 4wt%CNB were added to the sulphonated styrene butadiene rubber in solution and cast by the evaporative technique. Mechanical testing was done using Hysitron Nanotensile5000 Tester to evaluate the effects of blending. Tensile strength, σs, increased linearly (2 - 3.88MPa) with carbon nanoball volume fraction (Vf), achieving a maximum improvement of 94% at 14.2% Vf. The Young’s modulus, E increased as a power function of Vf, reaching a maximum of 79% (1agglomeration. The fracture toughness, Uf.t increased as a power function of Vf up to a maximum improvement of 215% (0.84 – 2.65MPa) at 14.2% Vf. Strain, e increased by a maximum of 63% (0.68 – 1.11) at 14.2% Vf. Higher ultrasonication amplitudes achieved superior dispersion effectiveness as compared to lower amplitudes. The nanofiller addition also significantly reduced degradation of mechanical properties with time. Below a critical nanofiller volume fraction, Vc, related to the fractional free volume of the polymer matrix, the E profile was consistent with existing models by Guth and Thomas. However, the coefficients of Vf, were significantly higher, which was attributed to the higher mechanical properties of carbon nanoballs as compared to the fillers assumed. Beyond Vc, agglomeration distorted the profile. The tensile strength profile for the well dispersed carbon nanoballs was different from the existing models by Nicolais and Narkis and Nielsen. It was concluded that the addition of [1-14vol% (1-4wt%)] carbon nanoballs improved the mechanical properties by a margin between 79% and 369%. With good dispersion, it can also be shown that prediction of mechanical properties for a given Vf was possible. Further work on dispersion improvement was shown to have the potential to increase the mechanical properties by up to 700%

An analysis of the spatial and temporal changes in the Riparian zone of the Berg River in the vicinity of Hermon: implications for governance

Riparian zones broadly refer to the interface between terrestrial and aquatic systems. It is widely acknowledged that riparian zones provide a number of services including that of an ecological corridor for migration of animal species; a habitat; food for aquatic macro invertebrates in the form of organic matter; stabilising river banks; filtering nutrients and sediments from water that discharges off surface slopes and land; and protecting and improving water quality of river systems. This study examines how the Berg River riparian zone has changed over the past few decades and then considers the implications for governance of these zones in South Africa. The study identifies changes in vegetation composition and spatial extent of the riparian zone. The study site is a stretch of the Berg River in the Hermon area. Changes in vegetation and the spatial extent of the riparian zone over time were identified and mapped using aerial photographs of the study area spanning a period from 1955 to 2012. The results of the study showed that the spatial extent of the riparian zone decreased by 29.3% from 55 ha in 1955 to 39 ha in 2012. At the same time the area covered by trees (Eucalyptus globules) increased from 3.84 ha in 1955 to 35.94 ha while the area covered by shrubs that could be detected from the sources, decreased from 46.10 ha in 1955 to close to zero in 2012. The results of this study reveal a lack of governance in the river system. The lack of governance is attributed to the fact that the Berg River Catchment Management Agency is not operational. In South Africa weak governance in the management and responsible care in safeguarding riparian zones has compromised water quality, ecological integrity and habitat of the river system

Determinants of voluntary or coerced sexual debut among Black African female adolescents in Soweto, South Africa: Findings from The Birth to Twenty Plus cohort study

Early sexual debut whether voluntary or coerced increases exposure to high risk sex which leads to unplanned pregnancy, sexually transmitted infections including HIV and reproductive heal th problems during adolescence. This study aim s to examine the risk factors for age of sexual debut, either voluntary or coerced among Black African female adolescents from the Birth to Twenty cohort study in Soweto, South Africa . Part A is the study protocol which outlines the rationale for conducting this study , study aim, research methodology, analysis plan and ethical considerations. Part B forms the literature review which gives a summary of the existing literature and provides context for the dissertation. The objectives of the literature review were to identify published literature on determinants of either voluntary or coerced sexual debut in adolescents and identify gaps for further research. Part C is the manuscript presenting the results and discussion on the implications of key findings. The results showed that there are many Black African female adolescents who are engaging in early sexual debut and there is prevalenc e of coerced sexual debut among adolescents of similar age. Socio-economic status and maternal education were found to be significantly associated with coerced sexual debut. There is a need for interventions to delay sexual debut among young female adolescents from low socio-economic backgrounds and lower maternal education

Research Notes : Notes on soybean nodulation with the indigenous Rhizobium in Zambian soils

Introduction : The work reported here was carried out under the auspi-ces of National Oilseeds Development Programme supported by the Research Branch, Department of Agriculture, Ministry of Agriculture and Water Development, Government of the Republic of Zambia, and the Food and Agriculture Organization of the United Nations. In the 1977-78 season, the couunercially grown soybean variety \u27Hernon 147\u27 was noticed to have nodulated profusely in a virgin land, without artificial seed inoculation. This was in the Mkushi area where soybean production then had just begun to expand

Smart and strategic procurement, use and maintenance partnerships in engineering equipment for sustainable development and training in Sub-Saharan Africa using a systems thinking approach

Abstract: Most engineering institutions in Sub-Saharan Africa generally suffer from the persistent shortage and lack of accessibility to modern engineering equipment for the training of engineers. The old and obsolete equipment available, invariably pose challenges on the caliber of engineers being churned out to run industries in these developing countries. Based on research carried out at four engineering institutions in Sub-Saharan Africa through data collection and analysis, a smart procurement, use and maintenance strategy in the form of strategic partnerships with industry was formulated using a systems thinking approach. This paper looks at the development of this strategy and how the proposed partnerships can help in sustainable development, capacity building and ultimately bridging the gap between industry and academia. The implementation of this novel approach at the University of Zimbabwe has brought immense benefits such as students and staff access to modern equipment and technology

Design of a 10-digit inventory codification system for a tube and pipe manufacturing company in Zimbabwe

Abstract: Lack of proper inventory control usually leads to high stock-outs resulting in ‘firefighting’. This paper looks at the engineering and technical services required to maintain smooth production with the aim of developing an inventory control system for the efficient utilization of resources. A work study was carried out at a tube and pipe manufacturing company in Zimbabwe followed by an analysis outlining the operations, limitations and process flows. An inventory audit provided some insights on the company’s inventory control status. A 10-digit inventory codification system was designed based on 7 rules for generic application and capability for ‘make or buy’ decisions on spare parts. A cost benefit analysis revealed that although the project would initially be costly, a reduction in inventory can be realized through removal of slow moving and obsolete stock, realizing some annual savings in the long run, coupled with an improvement in record keeping and accountability.Lack of proper inventory control usually leads to high stock-outs resulting in ‘firefighting’. This paper looks at the engineering and technical services required to maintain smooth production with the aim of developing an inventory control system for the efficient utilization of resources. A work study was carried out at a tube and pipe manufacturing company in Zimbabwe followed by an analysis outlining the operations, limitations and process flows. An inventory audit provided some insights on the company’s inventory control status. A 10-digit inventory codification system was designed based on 7 rules for generic application and capability for ‘make or buy’ decisions on spare parts. A cost benefit analysis revealed that although the project would initially be costly, a reduction in inventory can be realized through removal of slow moving and obsolete stock, realizing some annual savings in the long run, coupled with an improvement in record keeping and accountability

Process mapping and optimization of the process flows of a furniture manufacturing company in Zimbabwe using machine distance matrices

Abstract: Appropriate arrangement of machinery in a manufacturing environment can have a positive impact on the productivity of a company. A detailed work study carried out at a furniture manufacturing company revealed that parts travelled long distances before the final product is produced owing to the positions of machinery and crisscrossing process flows. This paper looks at how the plant layout was re-organized by mapping process flows and regrouping of the machinery according to their functions and products using machine distance matrices. Challenges relating to the plant layout, process flows, materials handling and transportation as well as assembly procedures were established, coupled with grouping machines according to functions and the least distance between interacting workstations. Using the machine distance matrices, processes were mapped and equipment reorganized to allow for continuous flow of production, resulting in significant reductions in transportation distances among interacting workstations and elimination of crisscrossing process paths

Modelling, simulation and optimization of the materials flow of a multi-product assembling plant

Abstract: Various dynamic factors impact the movement of materials within a manufacturing environment, increasingly becoming complex for multi-product assembling plants owing to the multiplicity and interconnectedness of these factors. Analyzing these factors can be equally complex, requiring modelling and simulation tools. This paper looks at the modelling and simulation of the materials flow of a multi-product furniture assembling plant to develop an efficient system that accomplishes timely product deliveries at minimal cost. Generic simulation models based on 2 products were developed and constructed using Arena® Simulation Software. Following the simulation experiments and implementation of the results, the average hourly throughput was significantly increased and additional space to store materials prior to processing at workstations was created. The generic models were compatible with the company's other products and hence useful for the company’s production planning and scheduling