Design, Fabrication and Performance Evaluation of Teff Cleaning Machine

Abstract

In this study, the teff (Eragrostis tef) cleaning machine was designed, constructed, and tested. The cleaner works by the principle of air-screen cleaning, which uses a fan system to remove lightweight materials and a mechanical system to remove materials with larger sizes. The machine consists of a feeding, separating and cleaning units, and power transmission components such as shafts, belts, pulleys, and bearings. The materials used for fabrication were based on the physical and mechanical properties of teff seed, design considerations like cost and availability of materials, and design analysis of machine components. The preliminary test of the machine with three feed rate and three sieve inclinations showed that the cleaning efficiency decreased from 88.72% to 69.35% for 0-degree sieve inclination, 97.85% to 73.67% for 5-degree sieve inclination, and 83.15% to 52.02% for 10-degree sieve inclination when feed rate increased from 5 kg/min to 15 kg/min respectively and the cleaning loss increased from 5.23% to 10.05% for 0-degree sieve inclination, 0.87%  to 4.37% for 5-degree sieve inclination and 10.17% to 25.70% for 10-degree sieve inclination when feed rate increased from 5 kg/min to 15 kg/min respectively. The result showed that for increased feed rate, the cleaning efficiency decreased and cleaning loss increased in general.