SCANNING SPEED INFLUENCE ON THE PHYSICAL PROPERTIES OF LASER METAL DEPOSITION TITANIUM ALLOY

The most commonly used aerospace titanium alloy, Ti6Al4V, was deposited on Ti6Al4V plate of dimension 72 x 72 x5mm. The laser power of 3 kW, powder flow rate of 1.44 g/min and gas flow rate of 4 l/min were used throughout the deposition process. The transverse/ scanning speed was varied between 0.005 to 0.095 m/sec according to established result of the preliminary study that produces full dense and pore free deposits. The mass of the deposited powder was obtained by weighing the substrate before the deposition and reweighing after the deposition. The substrate and the deposits were thoroughly cleaned using wire brush and acetone to remove unmelted powder particles from the surface of the substrate and the deposit. The height and width of the deposits were measured with Venier Caliper and the material efficiencies were determined using developed equations. The objective of this research is to determine the influence of the scanning speed on the material efficiency and deposit height in laser metal deposition of titanium alloy- Ti6Al4V. The results of this study showed that, for the set of processing parameter used in this study, the optimum scanning speed was at 0.015 m/sec with the optimum material utilization efficiency of 83.33% and the deposition height of 1.09 mm.  http://dx.doi.org/10.4314/njt.v36i1.1

Development of a mathematical model for managing magnitude and risk factors of injuries

A mathematical model was developed for managing m~gnitude and risk · factors of injuries in a manufacturing industry employing System Dynamics (SD) approach. Data were collected using an injury and illness investigation register. These were used to estimate and validate the parameters of the model. The principle of SD was employed to identify. the relevant risk management safety;_related components and their interrelationships. Results obtained from the experimenlal data depict a random periodic upwards and downwards trend in the magnitude of injuries; whereas the· predicted injuries yielded an exponential decay in the number of injuries occurrence. The means and standard deviations of the observed and predicted injuries were 27 and 9.08; and 26 and 6.61 respectively. The corresponding values for observed and predicted preventions were 18 and 9.08; and 19 and 8.48 respectively. A comparison of pr~dicted and observed injuries depict that the model _is useful for providing a decision support and predicting the main variables required for managing magnitude and risk factors of injuries in a bottling plant.Keywords: System dynamics, modeling, injury investigation, simulation, safety ma.nagemen

Development and preliminary testing of a parabolic trough solar water heater

Solar energy is. a high-temperature, high-energy radiant energy source, with tremendous advantages over other alternative energy sources. It is a reliable, robust renewable resource which is largely undeveloped. The design and fabrication of parabolic trough solar water heater for water heating was executed. The procedure employed includes the design, construction and testing stages. The equipment which is made up of the reflector surface (curved mirror), reflector support, absorber pipe and a stand was fabricated using locally sourced materials. The results obtained.compared favourably with other research works in the literature. It depicts that employing a suitable design, selection of time of heating and proper focusing of the reflected rays to the focal spot region, solar radiation can efficiently be utilized for  water heating in a tropical environment. This work presents a parabolic trough solar water heater as a suitable renewable energy technology for reducing water-heating costs. Keywords: Solar radiation, parabolic trough, water heater, focal spot, thermal efficienc