Abstract:
Cereals, including wheat, barley, oats, rice, maize, sorghum, and millets, are major grain crops
globally. Post-harvest grain loss is a significant issue in developing countries, in Ethiopia. Post harvest grain management practices are crucial for food security. Thus, the threshing of rice by
traditional and poor machine threshing units has its own problems on the quality and loss of the
product. As the result, rice producers (farmers and investors are often unable to obtain competitive
quality products from their farms and supply them to the market.
Threshing operations involve removing husks and straw from grains or seeds, either manually or
with animals or machinery. A study aims to design, analyse, and performance of a spike tooth rice
threshing unit in Ethiopia, focusing on drum speed and feeding rate.
The thesis study successfully designed, performance test, manufactured, and tested a spike-tooth
cylinder for a rice thresher machine, focusing on local materials suitable for low and medium
agricultural farmers. The model was created using SOLIDWORK software and imported to ANSYS
software for structural analysis. The study found that the maximum shear stress (360.87Mpa)
occurred at 1280 rpm of the spike tooth cylinder. The maximum equivalent stress was generated
at disc supports by nine levels of forces, while the torsional moments range from 97.89 to 681
4.741 MPa. Bending stress was highest at the highest speed of the spike tooth cylinder, causing
the threshing machine decreased performance. The study also assessed the performance of the
performance thresher at different drum speeds and feeding rate levels using R-STAT software.
Results showed that the maximum capacity was 458.3 g/min at 1280 rpm, and the maximum
threshing efficiency 98.16% was achieved at 5000 g/min and 7000 g/min. The interaction of drum
speed and feed rate significantly affected threshing efficiency
The interaction of drum speed and feed rate significantly affected threshing efficiency. The
maximum cleaning efficiency was achieved at 900 kg/hr feed rate and 1280 rpm, and the
interaction of drum speed and feed rate significantly affected cleaning efficiency. Higher speeds
resulted in greater grain breakage, while lower speeds had a moderate amount
