Performance Evaluation of an Acha Cleaning and Destoning Machine

The main objective of the study was to carry out an intensive performance evaluation of an acha cleaning and destoning machine in order to determine the parameters that affect cleaning and destoning of acha grain. The parameters investigated were de-stoning efficiency and cleaning efficiency. The effect of speed variations (350, 425 and 500 rpm) and deck tilt angle variations (4, 8 and 12 degrees) were verified at 5 % level of significance using Analysis of Variance (ANOVA) and means separation using F-LSD.The performance indicators investigated were Throughput capacity (TP), De-stoning Efficiency (DE), Acha Separation Efficiency (ASE), Impurity Level post-Separation (IML), Cleaning efficiency (CE), Chaff Separation Efficiency (CSE) and Tray Losses (TL).The result showed that the means of throughput capacity, de-stoning efficiency, impurity level after separation, acha separation efficiency, cleaning efficiency and tray loss of the machine were in the range of 36.96 to 49.82 kg/hr, 1.91 to 11.06 %, 11.60 to 37.73 %, 84.31 to 25.09 %, 88.40 to 62.27 % and 86.15 to 69.55 % respectively. The best results for de-stoning efficiency, acha separation efficiency and cleaning efficiency were obtained at machine speed of 350 rpm and tilt angle of 4 degrees to be 84.31 %, 88 % and 86.15 % respectively. Minimum impurity level after separation and tray loss of the machine were obtained at machine speed of 350 rpm and tilt angle of 4 degrees to be 1.91 % and 11.60 %. Maximum throughput capacity was obtained at machine speed of 500 rpm and tilt angle of 12 degrees as 49.82 kg/hr.