Development and performance evaluation of a manually operated onions grading machine

Abstract

Grading of onion bulbs carried out on the basis of size and shape is important for marketing uniform high quality produce for a better economic gain. A manually operated size grading machine for onion bulbs was developed aiming to achieve negligible mechanical impact on the onion in order to maintain its quality by using thin-layer foam of 5 mm as the cushioning material. The machine was designed to grade onions into three distinct size ranges of 0 − 40 m m , 40 − 60 m m and ≥ 60 m m . The grading performance of the machine was based on grading efficiency and grading capacity at non-cushioned and cushioned conditions for different treatment combination of the machine parameters (feed gate opening and crank revolution). The effects of feed gate opening [half ( F 1 ) and full ( F 2 )] and crank revolution [20(R1), 40(R2), 60(R3), 80(R4) and 100(R5) rpm) on grading efficiency and grading capacity of the developed grader were studied at α = 0.05 . The overall grading efficiency and grading capacity for the non-cushioned condition was 80% at F1R3 and F1R4; and 76.17 g/s at F1R3, respectively, while the overall grading efficiency and grading capacity for the cushioned condition was 77% at F1R3 and 82.75 g/s at F1R2, respectively. Statistical analysis of the data showed that feed gate opening and crank revolution at various levels combinations have significant effect on the grading performance at non-cushioned and cushioned conditions. • Development of a manually operated onion bulbs grading machine. • Evaluation of the performance of the developed machine based on grading efficiency and capacity. • Investigate the effects of feed gate opening and crank revolution on the machine performance.