Design and construction of a manually operated coffee grading machine.

Abstract

Uganda's economy is largely agro-based and in an attempt to improve the income base, the. developing technology has to meet the needs of the farmers. Coffee is by far one of the most important export crops accounting for 20-30 % of the country's foreign exchange earnings. It has provided employment opportunities to several people through coffee related. activities. In Uganda, the production level was 4 million 60 kg bags in 1999. The small scale. farmers are capable of growing 0.5 to 2.5 acres, under natural Ugandan climatic conditions, and yields between 6- 10 bags per- acre of Robusta coffee and 8-13 bags per acre of Arabica coffee. One of the major challenges in coffee production at smallholder level in Uganda is the lack of appropriate machinery to grade coffee beans by size which saves time, and reduces drudgery during grading. The current traditional method. for grading (hand picking) is labour intensive and time consuming. In a bid to improving quality of the beans, small scale farmers have massively responded to grading coffee beans by hand. The main objective of this project was to design, construct, and test the capacity and efficiency of the proto-type. In achieving the above objective, the researcher has carried out necessary calculations needed in the design, construction and testing the capacity and efficiency of the proto-type. The machine is limited to grade. Robusta coffee beans by size. Therefore, the project covered the design, construction and testing. Using basic engineering principles and some physical properties of coffee beans such as, size, density and weight, the various components of coffee grader were designed, and fabricated i.e. The hopper, Main frame, Grading chambers (Trays), Power mechanism. The sieves perforations were obtained to be 6.5mm and 5.5mm diameter for first and second sieves respectively; A Shaft having diameter of 14mm connects the cam to tray l. The drive was got by hand cranking to shake the grading chambers.