Development and performance tests of a sheanut cracker Original Research Article

A sheanut cracker was designed, constructed and tested to evaluate its performance. The cracker, which consists of a hopper fitted with a flow rate control device, a cracking unit, winnowing unit and power system, operates on the principle of impact using centrifugal force from a spinning disc. Results of performance tests showed that moisture content affected the performance indicators (percentage effective cracking, percentage breakage, percentage of partially cracked nuts, percentage of uncracked nuts and winnowing efficiency). Feed rate had a statistically significant effect on other indicators than the percentages of partially cracked and uncracked nuts at 5% level of significance. Disc vane configuration had no significant effect on percentage breakage and percentage of partially cracked nuts at the 5% level, but significantly affected both the percentage effective cracking and percentage of uncracked nuts at the 5% level, and winnowing efficiency at the 1% level of significance. The moisture content and feed rate that gave the highest cracker performance was found to be 22.7% (db) and 11.4 kg/h respectively. At the above conditions, the radial vane configuration, which among the three vanes employed, had maintained the best cracking performance, also gave the highest percentage effective cracking of practically 100% and about 97% winnowing efficiency. No breakage, partially cracked nuts and uncracked nuts were recorded with the radial vane configuration.