DEVELOPMENT OF AN IMPROVED SHEA NUT MACHINE

Abstract

One major problem affecting the shea butter industry is the shelling of the shea nuts. The existing machines used in place of the tedious manual method of shelling the nuts could not still solve the problems of kernel breakage resulting from impact of the hammering by the beaters’ in the machines. There is also the case of low feeds as it takes the machines long time to shell the nuts. Thus there is a need to develop an improved shea nut shelling machine to address these challenges. The improved machine with a horizontal impact rotating part was designed and fabricated based on the physical, frictional and mechanical properties of shea nuts which had been determined. The materials selected for the machine components were done based on these properties. The evaluation of the machine was carried out using feeds, speeds and moisture contents of the nuts and these were used to determine the shelling efficiency, cleaning efficiency, percentage breakages of the machine. Analysis of variance (ANOVA) was carried out on the results to verify the effects of these parameters on the shelling efficiency. The results showed that physical properties of mass, volume, and true density are 6.56±1.28 g, 11.02±1.78 ml, and .55±13 kml respectively. The frictional properties are the repose angle with 40.0o±1.36, and. friction coefficient, 32±.024 while the mechanical properties have the maximum cracking force of 207 N at 21.6 % moisture content on dry basis (d . b) in the lateral loading orientation. The maximum shell efficiency was 98 % at 152 kg/h feed rate, 10.7 % (d b) moisture content and at 1500 rev/min. The cleaning efficiency is 71 % at 10.7% (d b) moisture content at the same feed rate and speed. The recovery efficiency of 100 % was recorded at the moisture content of 21.37 % (d. .b) with the feed rate and speed remaining constant. It is therefore concluded that the machine is efficient in shelling the shea nuts.