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

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

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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Challenges and opportunities in implementing engineering systems thinking in design, manufacturing and process industries in Zimbabwe

- Nyemba, Wilson R., Mbohwa, Charles

  • Authors: Nyemba, Wilson R. , Mbohwa, Charles
  • Date: 2017
  • Subjects: Engineering , Manufacturing , Systems thinking
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/258916 , uj:27231 , Citation: Nyemba, W.R. & Mbohwa, C. 2017. Challenges and opportunities in implementing engineering systems thinking in design, manufacturing and process industries in Zimbabwe.
  • Description: Abstract: Engineering and manufacturing companies in industrializing countries such as Zimbabwe, largely employ traditional methods as well as conventional machine tools. Research carried out at five companies in Zimbabwe specializing in different business operations, similarly revealed that although such methods and tools are still applicable and productive, the processes are time consuming and the conventional machines often break down thereby delaying production. However, the research, which was conducted through interviews, direct observations as well as surveys, also revealed disconnections in 3 aspects of company policies, techniques employed and continuous professional development training. The research focused on establishing the challenges faced by the companies in implementing holistic approaches encompassing and integrating these 3 aspects. Recommendations were made for turning the various challenges into opportunities through adopting engineering systems thinking for integrating these aspects in order to improve capacity utilization, productivity and efficiency in the various companies.
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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

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

- Nyemba, Wilson R., Mbohwa, Charles

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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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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Development and fabrication of a wood gasifier to power an internal combustion engine

- Chinguwa, Simon, Nyemba, Wilson R., Jen, Tien-Chien, Boora, Kudzai

  • Authors: Chinguwa, Simon , Nyemba, Wilson R. , Jen, Tien-Chien , Boora, Kudzai
  • Date: 2018
  • Subjects: Carbon , Combustion , Fossil Fuels
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/285610 , uj:30890 , Citation: Chinguwa, S. et al. 2018. Development and fabrication of a wood gasifier to power an internal combustion engine.
  • Description: Abstract: Fossil fuels have been the main source of energy for many years hence the depletion of resource. There is therefore a need for alternative cleaner energy sources of fuel to be explored. The use of these conventional fuels led to land degradation global warming and air pollution. A wood gasifier machine which produces combustible gas from solid fuels like charcoal, wood and agriculture residue was designed. The combustible gas can be used for heating purposes or to produce mechanical or electrical energy. There was a great literature search for the technology currently being used for gasification processes which led to the design and manufacture of the gasifier prototype which was tested and came out successfully. An internal combustion engine was run on the combustible gas. Gasification bi-products that came out were tar and ash which could be used for water proofing and fertilizer respectively. Biofuels are renewable energy sources and are carbon neutral as they do not increase the total amount carbon dioxide in the atmosphere. The test also revealed some shortcomings in the design. The air which was used to allow for combustion to take place was inadequate, hence there is a need for further research.
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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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Development of an electric drive train for cycles as a sustainable means of transportation for a green environment

- Chinguwa, Simon, Nyemba, Wilson R., Ngondo, Emmanuel, 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

Evaluation and feasibility assessment of the sustainability of refrigeration systems devoid of harmful refrigerants for storage of vaccines

- Nyemba, Wilson R., Chinguwa, Simon, Marango, Batsirayi L., Mbohwa, Charles

Feasibility study and development of a sustainable solar thermal power plant through utilization of mine wastelands

- Nyemba, Wilson R., Munanga, Prominent, Mbohwa, Charles, Chinguwa, Simon

  • Authors: Nyemba, Wilson R. , Munanga, Prominent , Mbohwa, Charles , Chinguwa, Simon
  • Date: 2018
  • Subjects: System advisor model , Simulation , Solar thermal
  • Language: English
  • Type: Conference proceedings
  • Identifier: http://hdl.handle.net/10210/260423 , uj:27422 , Citation: Nyemba, W.R. et al. 2018. Feasibility study and development of a sustainable solar thermal power plant through utilization of mine wastelands.
  • Description: Abstract: Southern Africa has been grappling with power shortages over the last decade due to reduced generating capacities from the region’s few hydroelectric power plants and depleted coal reserves for thermal power generation. This forced many companies to operate below capacity, although potential and resources abound. Research was carried out at one of Zimbabwe’s platinum mining and mineral processing companies to utilize the vast surrounding wastelands with abundant exposure to sunshine throughout the year to augment supplies from the national grid. A spreadsheet model was developed to derive various parameters such as beam radiation, thermal to electric plant efficiency and optimum temperature to determine the heat output incident on collectors. The System Advisor Model (SAM) was then used to simulate the values to determine the arrangement of collectors on the proposed solar thermal tower power plant as well as cost the project. Simulation of the model showed that the designed solar thermal plant can generate 30 MW, a sustainable and feasible output to supplement supplies from the national grid.
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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

Modelling the integration of engineering design and manufacture for capacity building and sustainability

- Nyemba, Wilson R.

  • Authors: Nyemba, Wilson R.
  • Date: 2018
  • Subjects: Engineering design , Engineering - Study and teaching (Higher)
  • Language: English
  • Type: Doctoral (Thesis)
  • Identifier: http://hdl.handle.net/10210/293682 , uj:31939
  • Description: D.Ing. (Mechanical Engineering) , Abstract: Rapid changes in technology and industrialisation have enhanced the design and manufacture of products owing to improved links between product development and manufacture. However, resulting complexities due to interconnections and interdependences required appropriate skills and equipment, a rare commodity in industrialising countries due to technology and training insufficiencies. Studies carried out in Southern Africa revealed mismatches of skills produced by Higher Education Institutions (HEIs) and those required by industry, apart from the use of conventional equipment and technology which resulted in low productivity and declines in capacity utilisation. While taking cognisance of these challenges, the research aimed at developing alternative strategies using available equipment and expertise to boost productivity and capacity utilisation at selected case study companies and HEIs in Zimbabwe. This was motivated by lack of continuity and sustainability in initiatives that were supported by foreign aid agencies. The research was accomplished through a systems thinking integration of available technologies, skills and policies to cope with the rapid changes while enhancing capacity building and sustainability in engineering design and manufacture. Using a systemic philosophy and systems thinking methodology, this research utilised different approaches from work studies, industrial secondments and attachments by focussing on technologies, training and policies, factored from the highlighted challenges. Data was collected during secondments at selected companies and used for modelling, simulation and optimisation of the companies’ product design and production systems using Arena simulation software and Limn Flowsheet Processor. The optimisation results, coupled with collaborations between industry and HEIs were used as the foundation for the systems thinking sub-models that were eventually integrated into the Technology, Training and Policies (TTP) model which was validated and verified through a looping feedback, control and adjustment of system elements and tested through the University of Zimbabwe (UZ) groundwater enterprise model...
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Modelling, simulation and optimization of the comminution and flotation circuits of platinum for sustainable mineral processing

- Nyemba, Wilson R., Kapumha, Zvikomborero B., Mushiri, Tawanda, 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

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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