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 0−40mm, 40−60mm and ≥60mm. 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 (F1) and full (F2)] 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.

Keywords

• Manual operation
• Grading machine
• Onions
• Feed gate opening
• Crank revolution
• Cushioned