DESIGN, CONSTRUCTION AND PERFORMANCE EVALUATION OF ENGINE OPERATED MANGO (Mangifera Indica L.) FRUITS SIZE GRADING MACHINE

Abstract

Mango is a tropical fruit of highly seasonal, the most popular fruits and graded manual in Ethiopia. Hence, manual grading is time consuming, requires more labor and low output. So, this study was under taken with aims of design, construct and evaluate engine operated mango fruits size grading machine. The physical and frictional properties of local variety mango fruits were determined. The grader consists of mainframe, feeding table, grading unit, grading unit cover, outlets, collection boxes, engine sit, and wheel, handle and power transmission system. The experimental design used was factorial in a completely randomized design with two factors (three levels of speeds and feed rate with three replications). From the study, the mean fruits length, width, and thickness were 92.84, 71.74, 62.13 and 80.25, 58.56, 53.13 mm, for local and Alphonso variety respectively. The mean angle of repose was 39.72°for local and 33.71 for Alphonso and the coefficient of static friction on sheet metal 0.46, respectively. The main and interaction effects of machine evaluation on grading capacity, grading efficiency, fruits damages, fuel, and energy consumption were done. The maximum grading capacity of 1690.10 kg/h, grading efficiency of 90.66%, fruit damage of 1.94%, and fuel and energy consumption of 2.19 (mL/kg) and 2.34 w.hr./kg, respectively were obtained. Statistically, the main and interaction of speed and feed rate had a significant effect on grading capacity, grading system efficiency, percent of fruit damage, fuel and energy consumption of mango fruits size grading machine at (p < 0.05). The total cost of mango fruits size grading machine was estimated to be 29447.26 ETB with a cost benefit ratio of 1:6.25. Generally, it can be concluded that mango fruits size grading machine was simple in design, evaluation, easy in operation, and found to be suitable for medium-scale farmers, retailers and whole sellers