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
