Design, development, and evaluation of a motorized rice grader

The design and construction of a motorized rice grader were undertaken to classify rice grains into the head rice and broken rice. Three (3) screens of decreasing diameters were used inclined at angles ranging from 6, 8, and 160 and driven by a 5 hp motor to cause agitation and a pneumatic mechanism for blowing light chaff material. The performance efficiency of the developed machine was evaluated with milled rice at 15% moisture content (wet basis) at different feed gate levels (FGL) (5 to 20 mm). The result indicated decreased grading efficiency (GE) and product purity (PP) with increased FGL, increased throughput capacity (TPC) and tray loss (TL) with increased FGL. The highest GE and PP were 91.67 and 90.97% at 5 mm FGO, while the highest TPC and TL were achieved at 20 mm FGL as 0.08 kg/s and 1.06%, respectively. The feed gate levels (5 to 20 mm) had a significant effect on the performance efficiencies investigated.