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The operational parameters of threshing drum play a dominant role in the design and development of the finger millet thresher-cum-pearler. The finger millet threshing drum was developed and effects of operational parameters such as feed rate, drum speed and concave clearance on threshing efficiency, pearling efficiency and grain damage were individually studied using response surface method. A statistical tool of the central composite rotatable design was used for analysis. It was found that the maximum threshing efficiency, maximum pearling efficiency and minimum grain damage were 98%, 85% and 0.086%, respectively at the feed rate 36 kg/h, drum peripheral speed 7.12 m/s and concave clearance 5 mm. The performance evaluation of the drum was validated by setting above condition in the threshing drum. It was found that the maximum threshing efficiency 99% against predicted 98%, maximum pearling efficiency 86% against predicted 85% and 0.1% grain damage was found against predicted 0.086%.

Finger millet pearling process involves so many drudgery prone operations that specify the need for the development of finger millet pearling drum. The performance of pearling drum depends on its operational parameters. Therefore, this study aims to optimize the operational parameters of the pearling drum such as drum speed, concave clearance and pearling sieve size to obtain maximum pearling efficiency and minimum grain damage. The analysis was carried out using Response Surface Method along with the Box-Behnken Design tool. The optimum operational parameters were found as drum speed 7.25 m/s, concave clearance 3 mm and pearling sieve size 2 mm that predicts the maximum pearling efficiency of 98.95% and minimum grain damage of 0.73%. Finally, the performance of the pearling drum was validated setting optimum conditions. It results pearling efficiency of 99% along with 0.5% grain damage. Above results indicates that the validated pearling drum performance was better than predicted.

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