Modeling and analysis of the effect of distances between hammers and sieves on some performance indicators of hammer mill machine

This study was conducted to determine the effects of concave clearance and rotational speed on hammer-mill performance when grinding chickpeas. A response surface methodology (RSM) design approach was used to determine its suitability as a predictive approach for optimize chickpea flour production. The evaluation was performed using two parameters, concave clearance (6 mm, and 9 mm for the manufactured screen) and rotation speeds of (2154 rpm, 4339 rpm) as test factors, while Power Consumption (PC), Productivity (P), Specific Capacity (SC), Specific Energy (SE), Average Granules diameter (AG) and Grinding Fineness (GF) were used as test indicators. A quadratic regression combination test was designed and a mathematical model between the test indicators and the test factors was constructed. All models were statistically significant and were validated with two independent variables. The model R2 for the responses was 0.87, 0.87, 0.71, 0.72, 0.91, and 0.93 for PC, P, SC, SE, AG, and GF, respectively. The results showed that the effect of concave clearance was significant for P, SC, SE, and AG; while PC, and GF were not significant. Furthermore, rotational speeds was significant for all indicators. The 9 mm concave clearance and the rotational speed of 4339 rpm were the most acceptable, so the new 9 mm concave clearance screen has a high productivity of 248.63 kg.h-1 and reasonable power consumption of 1.82 kW, which is aprpperate in feed quality and preservation. After optimization the hammer mill showed the best operating performance meeting the requirements of precision grinding of chickpeas.