Design and Assessment of a Small-Scale Machine for Cleaning Wheat Grains

A small-scale wheat cleaning machine was designed to winnow and separate grains from materials-other-than-grains (MOG), such as premature grains and chaff, in order to enhance the quality of grains. It was evaluated technically with respect to assessment criteria: cleanliness, grain loss, chaff rejection, and cleaning efficiency. Experiments were carried out at three levels of sieve slopes (5, 10, and 15°), two sieve reciprocating speeds (0.48 and 0.95 m·s⁻¹), two levels of feed rates (1 and 1.5 kg·min⁻¹), and three air velocities (5, 6 and 7 m·s⁻¹). The results showed that, at sieve reciprocating speed of 0.95 m·s⁻¹, the maximum cleanliness value was – 96.25% – observed at 1.5 kg·min⁻¹ feed rate, 5 m·s⁻¹ air velocity and 5° sieve slope. The minimum cleanliness value – 76.82% – was observed at a feed rate of 1 kg·min⁻¹, 15° sieve slope, 7 m·s⁻¹ air velocity, and 0.48 m·s⁻¹ sieve reciprocating speed. The results showed that the use of either a very low, or a very high sieve slope angle and sieve reciprocating speed while using different air velocities and feed rates is not recommended.