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Feasibility study of the materials handling and development of a sustainable conveying system in plastics recycling and manufacture

- Chinguwa, Simon, Nyemba, Wilson R., Boora, Kudzai, Mbohwa, Charles

Production planning and control of a master churn mixer for the manufacture of margarine using fuzzy logic at an oil company in Zimbabwe

- Nyemba, Wilson R., Mushiri, Tawanda, Mugwindiri, Kumbi, Mushonga, Roy, Mbohwa, Charles

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

- Nyemba, Wilson R., Mbohwa, Charles

Nonlinear finite element program for reinforced concrete structural control

- Mushiri, Tawanda, Nyemba, Wilson R., Mbohwa, Charles

Equipment maintenance challenges and solutions for capacity building and sustainability in the training of engineers : the case for the University of Zimbabwe

- Nyemba, Wilson R., Mashamba, Able, Mbohwa, Charles

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

- Nyemba, Wilson R., Mbohwa, Charles

  • Authors: Nyemba, Wilson R. , Mbohwa, Charles
  • Date: 2017
  • Subjects: Inventory control , Manufacturing , Maintenance
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/224997 , uj:22714 , Citation: Nyemba, W.R. & Mbohwa, C. 2017. Design of a 10-digit inventory codification system for a tube and pipe manufacturing company in Zimbabwe. 14th Global Conference on Sustainable Manufacturing, GCSM 3-5 October 2016, Stellenbosch, South Africa. DOI: 10.1016/j.promfg.2017.02.064. , ISSN: 2351-9789
  • Description: 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.
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Conceptualization of a new product development framework for eddy current braking systems for heavy vehicles in Zimbabwe

- Nyemba, Wilson R., Pote, Chris, Chikuku, Tauyanashe, Mbohwa, Charles

A new product development framework for a timber processing company

- Nyemba, Wilson R., Mushiri, Tawanda, Mbohwa, Charles, Shoniwa, Kuda J.

  • Authors: Nyemba, Wilson R. , Mushiri, Tawanda , Mbohwa, Charles , Shoniwa, Kuda J.
  • Date: 2016
  • Subjects: New product development , Quality function deployment , Stage-Gate modelling.
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/91902 , uj:20160 , Citation: Nyemba, W.R. et al. 2016. A new product development framework for a timber processing company.
  • Description: Abstract: Customer perceptions of products continuously change over time. Marketing specialists are generally tasked with the responsibility of rebranding and product changes. However this is normally technology driven, with inputs from engineering designers and manufacturers providing the designs and feasibilities for either modifying existing designs or developing new ones. An opportunity arose at a timber processing company where a variety of products such as domestic and commercial furniture are manufactured. This paper reports on the development of a framework for formulating new products using the wide array of hard and soft wood that the company processes. A work study was conducted, focusing on the company’s production capacity, sales history of their twenty-three products, market trends and interviews with current customers. The research set out to develop innovative and new product platforms (product families) that are unique and represent the company while satisfying customer needs and requirements. A stage-gate model of the New Product Development (NPD) framework was formulated. Coupled with Quality Function Deployment (QFD) and weighted objectives, the use of the stage-gate model was demonstrated in the development of a four wheeler coffee table into a prototype. Implementation of the stage-gate model and further research into the four-wheeler coffee table were recommended as well as other areas related to NPD.
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Unlocking the economic value and potential of design for manufacture and assembly in a developing country for sustainability

- Nyemba, Wilson R., Muzoroza, R. K., Chikuku, T., Mbohwa, Charles

Customization of the CAD software in a typical drawing office for a power and electricity distribution company in Zimbabwe

- Nyemba, Wilson R., Mbohwa, Charles

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

- Nyemba, Wilson R., Mbohwa, Charles

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

- Nyemba, Wilson R., Mbohwa, Charles, Nyemba, L. E. N.

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

- Nyemba, Wilson R., Mbohwa, Charles

Development of an effective self-cleaning system to minimize fouling in heat exchangers

- Nyemba, Wilson R., Chinguwa, Simon, Zimba, Isheanesu, Mbohwa, Charles

  • Authors: Nyemba, Wilson R. , Chinguwa, Simon , Zimba, Isheanesu , Mbohwa, Charles
  • Date: 2018
  • Subjects: Condenser , Fouling , Foulant
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/285603 , uj:30889 , Citation: Nyemba, W.R. et al. 2018. Development of an effective self-cleaning system to minimize fouling in heat exchangers.
  • Description: Abstract: Power plant steam condensers use cooling water for condensation of exhaust steam from turbines. Depending on the concentration of cations in the cooling water, changes in temperature result in the precipitation of insoluble metal salts on the tube walls hence impeding heat transfer, leading to fouling, a threat on the heat transfer efficiency of the condenser. The research was carried out at a power station in Zimbabwe where offline mechanical methods used to clean the tubes were observed to be slow and inefficient, hence increasing downtimes. The use of spherical rubber balls was proposed where they were injected into the cooling water to scrub off dirt on the tube surfaces as well as creating turbulence to prevent the dirt from settling on the tube walls. Ball sizes of diameter less than the tube sizes were preferred in order to cater for possible thermal expansion of the rubber material on exposure to elevated temperatures. A magnetic water treatment unit was added to facilitate the formation of weak precipitates of the metal salts for ease of removal on cleaning. The design and implementation of the research results had the potential of saving the company on downtimes during condenser cleaning.
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Software development of a catalogue of engineering symbols as an add-on facility for use in CAD

- Nyemba, Wilson R., Mbohwa, Charles

Optimization of a plant layout and materials handling system for a furniture manufacturing company

- Nyemba, Wilson R., Mbohwa, Charles, Nyemba, Lloyd E.N.

  • Authors: Nyemba, Wilson R. , Mbohwa, Charles , Nyemba, Lloyd E.N.
  • Date: 2016
  • Subjects: Materials handling , Plant layout , Process mapping
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/92044 , uj:20179 , Citation: Nyemba, W.R. Mbohwa, C. & Nyemba, L.E.N. 2016. Optimization of a plant layout and materials handling system for a furniture manufacturing company
  • Description: Abstract: The proper layout and efficient utilization of resources; human, machinery and space can have a positive bearing on the productivity of manufacturing companies. A case study was carried out at a furniture manufacturing plant in Harare, Zimbabwe and this paper presents the findings and proposals for an optimized plant layout and materials handling system. Inherent problems within the manufacturing setup were identified through the use of questionnaires and the company’s available documentation. These ranged from crisscrossing process flows, undocumented production plans and inadequately planned materials processing and handling. Following a detailed work study, production planning and control techniques for materials handling, processing and assembly were introduced to improve production throughput times. Three alternative models were conceptualized and the best model was selected using the payback period method while optimization of the plant was achieved through a novel approach of process mapping of the layout, available space and materials handling machinery. Results obtained from the assessment of the selected model revealed that transportation distances can be reduced significantly while production throughput time decreases.
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Waste heat and energy recovery system from smelter off-gas for a platinum processing plant

- Nyemba, Wilson R., Mushanguri, Innocent, Chinguwa, Simon, Mbohwa, Charles

A systems thinking approach to collaborations for capacity building and sustainability in engineering education

- Nyemba, Wilson R., Carter, Keith F., Mbohwa, Charles, Chinguwa, Simon

Data collection and statistical data analysis in preparation for simulation of a furniture manufacturing company

- Nyemba, Wilson R., Mbohwa, Charles

  • Authors: Nyemba, Wilson R. , Mbohwa, Charles
  • Date: 2016
  • Subjects: Data collection , Manufacturing , Statistical analysis
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/91956 , uj:20166 , Citation: Nyemba, W.R. & Mbohwa, C. 2016. Data collection and statistical data analysis in preparation for simulation of a furniture manufacturing company
  • Description: Abstract: Systems that are simulated are generally made up of one or more elements that have some uncertainty associated with them. These systems may eventually evolve in a manner that is not completely predictable and thus become stochastic in nature. Simulation of stochastic systems requires that the variability of the elements in the system be characterized by probability distributions or concepts. An 'As- Is-Analysis' of the plant layout and product process flows was carried out at a furniture manufacturing company. Process data for four of their main products namely, pallets, baby tenders bunk beds and standard coffins was collected using a specially designed data sheet. An analysis of the product flow times was carried out by grouping the data into four time variables namely, material movement, processing and waiting (idle) times before and after processing at the active workstation. The distributions of these variables were obtained using graphical methods in which smooth distribution curves were generated. The gamma distribution with shape parameters of α= 3 and α=2 characterized the baby tenders while the product flow times for pallets were characterized by both the gamma distribution, α=3 and the exponential distribution with the mean varying between 14.95 and 271.78 seconds. All the data and analysis carried out produced useful information for input to the design of experiments for simulation.
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Challenges and opportunities in adopting and implementing sustainability plans in engineering, mining and processing companies in Zimbabwe

- Nyemba, Wilson R., Mbohwa, Charles

  • Authors: Nyemba, Wilson R. , Mbohwa, Charles
  • Date: 2018
  • Subjects: Capacity utilization , Decision making , Sustainability planning
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/260422 , uj:27421 , Citation: Nyemba, W.R. & Mbohwa, C. 2018. Challenges and opportunities in adopting and implementing sustainability plans in engineering, mining and processing companies in Zimbabwe.
  • Description: Abstract: Zimbabwe is endowed with a plethora of natural resources sufficient to provide raw materials and inputs to its engineering, mining and processing companies. Despite having inherited functional industries at independence, over the last 15 -20 years, the country has been grappling with recession, low capacity utilization, liquidation of companies and failure to export, let alone meeting local requirements. Although political instability has been largely attributed to this failure, ongoing research through surveys, interviews and direct observations at five companies involved in different business portfolios namely, furniture manufacturing, general engineering and foundry, assembly and manufacture of bus and truck bodies, backup and service of heavy vehicles as well as mineral processing, similarly revealed not only the lack of sustainability plans but also lack of involvement of all stakeholders in decision making in a systems thinking approach to ensure business continuity in different situations. The research also revealed that the failure to meet current needs without compromising the needs of the future could have contributed a great deal to low capacity utilization and eventual liquidations. Recommendations made to the companies were welcomed as clear opportunities to learn from the past and these are helping the companies to gradually recover and regain economic value in spite of the difficult operating environment.
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