Design and fabrication of a motorized multi-grain winnowing machine.

Abstract

Grain production in Uganda is dominated by small-scale subsistence fanners as 95% of the production is by small-scale subsistence and the rest by commercial fanners respectively (FAD and Agal, 2.Q.0.5),A variety of grains grown in many. Households season after season act as food crop for food security and as cash crop for income generation (FAO and Agal~2005). For grains to be utilized in any' form they need to be winnowed though the Winnowing stage determines the quality, quantity of the cleaned grains.as rudimentary methods of winnowing lead to high loss and low quality of cleaned seeds plus low market value (Greeley, 1:982). The local farmers in Uganda usually winnow their grains by pouring them out of a basket and letting the wind blow off the chaff. However, this sometimes causes recontamination of the grain with the already blown out chaff, its time consuming and can cause some airborne diseases like flu to those involved in the operation. This is as a result of absence ora machine capable of winnowing a variety of large quantities of the wains that are grown in different seasons by farmers and the existing winnowing machines on market do winnow a specific, grain. this demanded an extensive research in' the area of grain Cleaning in Which the researcher came up with the design and construction of a motorized multi- grain winnowing machine that will t:;frectiyelyaddress the above mentioned problems faced by farmers as the main reason for-the research. The main objective of this project is to develop a motorized multi-grain winnower that meets farmers' winnowing. Requirements in achieving the above objective, the researcher has carried out necessary research, assumptions and calculations needed considering the basic engineering. Principles and some physical properties of grains such as, angle of repose, bulk density. And weight of the grains, to design the various components of multi-grain winnower-which has parts such main frame, hopper, wind duct assembly, regulating plate, blower, fan, driver shaft and a 2 horse power electric single phase motor. The researcher fabricated the designed parts from locally sourced materials, assembled them following recommended procedures and methods as discussed in this report. The performance test and evaluation was successfully conducted and output capacities of 0.1.67Kglhr and .3.8:.KgLharnd cleaning. efficiencies of 84.42% and 7437% for beans arid rice respectively as test grains were achieved, The cost of producing a multi-grain winnowing prototype up to the final. Time of its fabrication was 920,700 Ugx excluding the cost of purchasing the electric motor and the power required' for operating the machine was iA9KW. A motorized multi-grain winnowing machine was designed; fabricated and tested. With the test results and the cost-benefit analysis results attained, the prototype will ameliorate the associated problems and difficulties in the traditional methods of winnowing a variety of grains grown by farmers.