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

Abstract

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.