Optimizing operational parameters of finger millet threshing drum using RSM.

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%.