DESIGN AND MANUFACTURE A PROTOTYPE OF YEMENI COFFEE HULLER MACHINE

Abstract

The design, construction and development of a huller is described in this paper. Some engineering properties were studied as important parameters affecting the design of the huller machine, and the results showed that, the highest frequency length, width and thickness of the coffee grains were 1.0, 0.7 and 0.7 cm. The medium size (from 7-10 mm) was denser than both small and large sizes of coffee as the porosity of that size was lower than those of both small and large sizes. The angle of repose increased with the decrease of coffee size. It ranged from 8.75 to 14.30 degrees on the glass surface. The huller consists basically of a drum, hopper, fan, motor, frame, belts and pulleys. It was tested at different speeds and feeding rated. The results indicated that the huller productivity increased with increasing the drum rotation speed and feeding rate. The productivity ranged from 240-360 kg/h. It could be used for hulling the coffee beans at higher rotation speeds with high efficiency.