Abstract:
Maize (Zeamays) is the third most important cereal. grain worldwide after wheat and rice. The importance of maize is centered on the large quantity of Carbohydrates and significant quantities of proteins, vitamins and fats, contained in the kernels, making it compare favourably as an energy source with root and tuber crops. Winnowing and Cleaning of grain is usually done prior to storage or marketing if the grain is to be sold directly. For the majority of smallholder grain processors, this process is undertaken. manually, it is relatively ineffective from a commercial- perspectives since grain purchased from smallholders frequently requires screening to remove stones sand, and extraneous organic matter. -There is little incentive for to provide well-cleaned grain for marketing, as there is usually no premium for quality; rather, there. is every incentive to leave foreign matter in the grain, especially at the bottom of sacks, so that profits from sales can be maximized. Therefore, the objective of the study was to design, construct, test and carry out economic evaluation of a maize grain cleaner for- small and medium scale agro- processing units. This would therefore, result in reduced- bulk of the material by reducing the level of physical contaminants, thus reducing transport -costs and optimizing storage space, safe and longer storage more out-turn of better quality milled products.
The •design of the various machine parts •was by analysing forces acting on them. Force analysis led to selection of proper materials to withstand the forces to avoid failure. Stainless steels of various grades were -the main materials recommended 10 be used because they are food grade, strong and durable. Engineering drawings of the various components were drawn before the various components were constructed and then machine parts fabricated. A fully functional. prototype resulted after all the above operations. Testing of the prototype was carried out and the figures revealed that the machine was 75.5% efficient The maize grain cleaner has a total cost of 975, 675 UGX which includes all the taxes, cost of material, machinery and hired labor to construct the machine plus overhead costs. The cost evaluation analysis of the project was based on the payback period the project was evaluated-to breakeven in 3 months.
