https://hdl.handle.net/10646/151 Tue, 21 Apr 2026 01:47:52 GMT 2026-04-21T01:47:52Z https://hdl.handle.net/10646/3850 Design of an electrically powered bending machine: case of Zimbabwe Mushiri, Tawanda; Shumba, Definite; mbohwa, Charles This paper seeks to carry out design of a small scale electrically powered bending machine for a developing nation, case for Zimbabwe. The bending of metal is of great importance in the manufacture of products such as nut shelling machines and maize shelling machines. Currently being used at Company X engineering is a manual bending machine with a single operation hence this design will help to increase the number of metals being bent, an increase in the efficiency and production. The paper deals with manufacturing or bending of sheet metal by using power operated sheet bending machine. Especially discussion made the productivity analysis of manually or power operated sheet bending machine. Considering manual operation is replaced by power operated devices. It also gives information about limitation of manually operated sheet bending machine and power operated sheet bending machine. The existing machines are limited to a single operation. The aim of the research is to increase the number of bent parts and to place an adjustable table to suit the height of the user thereby reducing back pain internal injuries in the long run. The researchers visited the Company X to gather information concerning the problems faced by the employees. Material tests which are of great value were carried out and the use of software. A Plate Rolling Machine is a machine that will roll different kinds of metal sheet into a round or conical shape and a rod bending machine will roll or bend different kinds of metal sheet into right angles or circular shapes. The research aims at making it possible to do the operations on a single machine. We recommend the machine to be automated and the use of a servo motor to reduce human injuries at the workshop. Use of oils and maintenance is of great value to increase the life span of the machine Tue, 11 Apr 2017 00:00:00 GMT https://hdl.handle.net/10646/3850 2017-04-11T00:00:00Z https://hdl.handle.net/10646/3567 Sizing and economic analysis of a solar photovoltaic micro power system for Arundel Boarding house with or without net metering. Mukucha, Kundayi, V.; Hove, Tawanda; Mushiri, Tawanda In this research, a hybrid solar photovoltaic micro power system that would improve the power supply reliability to desirable levels at the least possible cost was designed for Arundel Boarding House in Mount Pleasant experiencing drastic load shedding and yet accommodating University of Zimbabwe students. A solar powering system required to improve electricity supply reliability, was sized using a Microsoft Excel simulation model for a hybrid solar power system, designed using solar geometry and radiation relationships and also using dimensionless parameters. All the size variables where expressed as dimensionless parameters in order to generalize the system such that it would be useful to other places with the same economic conditions, solar radiation and load pattern. The program takes into account solar climatological data like solar radiation, ambient temperature and variability of the electrical load and then computes the energy, supply, reliability, LCOE as output. The reliability level was set and the combination that got the least LCOE was noted using the graphing method. Cost advantages of net metering (a billing mechanism that credits individuals who generate off-grid electricity for the electricity they add to the grid) were compared. The Excel model revealed that 5 of A/A0 (dimensionless parameter for array area) required supplying power of 15.46kW, 15.46kW inverter power and 76.81kWh of battery capacity for a daily demand load of 74.212kWh. In the project it was shown that with net metering the least LCOE resulted in 24.0c/kwh whereas without resulted in 29.1c/kWh and showed that the use of net metering can reduce significantly the cost of the power system. The Grid-tied photovoltaic powering system was found to be more cost efficient when utilizing the net metering strategy LCOE as 24c/kWh at a reliability of 99%. Hence the government should implement/legislate the net metering strategy to improve the reliability of supply of grid electricity. Conference paper Sun, 01 Jan 2017 00:00:00 GMT https://hdl.handle.net/10646/3567 2017-01-01T00:00:00Z https://hdl.handle.net/10646/3495 Design of a sawdust pelleting machine Mushiri, Tawanda; Mugodo, Peterson; Mbohwa, Charles This paper seeks to carry out the design of a pelleting machine with a capacity of 900kg per hour for the Company X. Apparently the boilers at the plant are using wood chips, a by-product from the milling operations as their source of fuel but off late the plant has been experiencing a serious fuel shortage. The fuel crisis emanated from low plant availability caused by old and dilapidated machinery. Major breakdowns that brings the plant to a halt for long hours are abrupt and rampant and during that time no wood chips are produced resulting in a fuel shortage. Following this fuel shortage the boiler operators have resorted to rationing the fuel input into the boiler as it has to run continuously regardless of whether the plant is moving or not. This rationing has resulted in poor boiler performance and low efficiency which has in turn affected the timber drying kilns. The boilers are producing poor quality steam which has had the effect of doubling the timber drying cycles. As a result of doubled timber drying cycles half of the timber produced is sold as wet off sawn at a relatively low price which is a loss to the company. The management and the engineering team in a bid to do away with this problem proposed the use of sawdust as additional boiler fuel. After a consideration of the type of boiler fire grates at the plant it was found that raw sawdust cannot be used as it has a tendency of choking the grates blowing out combustion so it has to be pelletized. With this problem at hand this project zeroed in at the design and development of a pelleting machine that will specifically meet the pellets need at the wattle company. Literature review was done on several types of pelleting machines’ operating mechanisms and from this literature three possible concepts were generated. These concepts were evaluated and the best was chosen and developed into a finished design ready for fabrication with all working drawings available for each component. The machine was designed with a constraint budget of USD $10 000 and it will provide a backup and additional boiler fuel to the already being used wood chips. Conference paper Tue, 11 Apr 2017 00:00:00 GMT https://hdl.handle.net/10646/3495 2017-04-11T00:00:00Z https://hdl.handle.net/10646/3469 Design of a rice transplanter for Zimbabwean farmers Mushiri, Tawanda; Gutsa, Brighton; Mbohwa, Charles Rice is a crop of growing importance in Zimbabwe but with a production of only 700 metric tonnes. This is because in wetlands it is largely grown by broadcasting of seeds and seedlings; and manual transplanting of seedlings. In practicing the said method however, farmers are exposed to musculosketal disorders as well as back problems due to the repetitive bending as well as the awkward posture needed in performing the task. Though manual transplanting gives uniform crop stand it is quite expensive and requires lot of labour besides involving lot of drudgery. Singh et al., 1985 reported that transplanting takes about 250-300 man hours/ha which is roughly 25 per cent of the total labour requirement of the crop. The rice production in Zimbabwe has also been very low because the common rice types were affected by the local climatic conditions however in 2014 businessman and farmer struck a deal with renowned Chinese agricultural scientist for National Hybrid Rice Research and Development Centre in Changsha in Hunan Province to start a pilot hybrid rice production exercise that could easily transform Zimbabwe into a major rice growing hub in the SADC region using varieties suitable to local conditions. This paper aims to design an ergonomic rice transplanter suited for the Zimbabwean climate and terrain. The mechanical transplanting of rice has been considered the most promising option, as it saves labour, ensures timely transplanting and attains optimum plant density that contributes to high productivity. Mechanization of rice sector will lead to higher productivity with releasing of work force to other sectors. Thu, 11 Apr 2013 00:00:00 GMT https://hdl.handle.net/10646/3469 2013-04-11T00:00:00Z