Design for manufacture and assembly of a mini combine wheat harvester: Case of a developing nation - Zimbabwe

The Zimbabwean Fast Track Land Reform Programme (FTLRP) (2000) resulted in the creation of smaller land pieces which, although beneficiary in that land was indigenised, were however not suitable for farming most cereal crops, particularly wheat. This is because the available machines used for the harvesting processes are mostly designed and economical for large pieces of land. In order to serve those small scale A2 wheat farmers who have resorted to time consuming and laborious manual harvesting methods, and to encourage those who have abandoned wheat farming completely, this paper was done to design a mini combine harvester machine that is both affordable and economical for these farmers. Design specifications and drawings were developed for the machine. Information for the manufacture and assembly of the mini combine harvester was also provided, and material selection was done focusing on the locally available and affordable materials in the country. Manufacture of this mini combine harvester will result in profitable wheat farming by small scale farmers and will also boost the gradually declining wheat grain production. For most practical industrial applications, a transmission shaft with span length L (distance between two adjacent bearings), the maximum deflection δ lies in the range of 0.001L < δ < 0.003L. In the design process, reaping and threshing systems were designed through the use of the crop requirements. These include the mechanical and physical properties of the wheat kernel and straw properties. The mechanical and physical properties used have been obtained from various studies carried out on determining them, focusing mainly on the varieties being grown in Zimbabwe. Theresearchers scaled down other systems, that is reduce them in size to cater for the mini combine harvester. The von Mises stresses were done using SolidWorks and they were in range and the weakest point was determined.