Design Modification and Performance Testing of a Bambara Groundnut Sheller

A centrifugal Bambara groundnut pod shelling machine was earlier designed and constructed to crack various sizes and varieties of Bambara groundnut. The sheller was fabricated and designed with locally available materials. The machine consists of three main units, namely the hopper, shelling unit and power transmission unit. The sheller only cracked the nuts with it product being the shell and the kernel combined. The results of the test showed that the cracking efficiency, seed breakings, partially shelled pods, unshelled pods and the machine capacity were 83.2 %, 17.4 %, 7.8 %, 9 % and 75000 seeds/hr respectively. This design was modified to incorporate a separating unit to save timeliness of operation and enhance efficient processing of Bambara groundnut. A bulk quantity of Bambara groundnut pods purchased from a local market. The moisture content of the Bambara groundnut pods was varied at five different levels; 5.2, 8.9, 12.9, 17.2 and 21.4% (d.b). One hundred pods were selected for each pod sample and introduced into the centrifugal cracker. Result showed that 5.2% moisture content gave the best performance of 87.5% shelling efficiency, 2.8% breakage 4.5% unshelled pods, 5.2% partially shelled pods and winnowing efficiency of 86.7%. The blower speed was varied at three different levels (1800, 1450, 1000 rpm) respectively. Results showed that blower speed of 1800rpm gave the best performance of winnowing efficiency of 86.7%.