Performance Evaluation of a Variable Pitch Potato Grader

Abstract

Manual grading of potatoes in Kenya has resulted in inconsistencies, quality variations and financial losses to small-scale farmers due to low market prices for poorly classified produce. To mitigate these challenges, this study aimed at developing and evaluating the performance of a potato grading machine to enhance uniformity and overall quality of potato tubers. The research involved determining the engineering properties of Shangi potato variety and developing potato grader machine. The designed grader consisted of a feeding hopper, conveyor belt, grading unit, and collection trays. Grading capacity, grading efficiency, and mechanical damage index were assessed by varying grading unit speeds, angles of inclination and feed rates. The results showed that the grading capacity increased with higher grading unit speeds, inclination angles, and feed rates. The optimal operating conditions were observed at a grading unit speed of 4 rpm, an inclination angle of 0 degrees and a feed rate of 3400 kg/hr. The prototype potato grader achieved a grading capacity of 3968 kg/hr, with an efficiency of 89.34% and a mechanical damage index of 2.94%. The results demonstrate that the potato grading machine effectively enhances grading efficiency while minimizing mechanical damage. This grading machine offers a practical and sustainable solution for small-scale farmers to produce high-quality graded potatoes in line with market demands. It is recommended that future research may include further optimization by exploring various grading unit speeds, feed rates, and inclination angles. Implementing padding on the collection trays could further reduce mechanical damage to the graded tubers. Furthermore, investigating alternative power sources may enhance the grader's versatility and extending testing to fruits and other tubers would broaden its applicability in the agricultural industry.