Development and Performance Evaluation of a Hand Operated Maize Sheller

Abstract

Maize is a popular food crop of the world. After harvest, maize is shelled traditionally by small holders of farms. This method has not proved to be effective due to drudgery attached, kernel breakage and poor shelling capacity. Over time, motorized shellers have been introduced to address the challenges faced by processors; they have not gained widely adoption due to unaffordable cost of owning one. There is the need to design a cost effective and eco-friendly solution that will suit the need of subsistence farmers in the industry. This work focuses on development of a hand-operated maize sheller. A major component is the lever arm fitted to a ball bearing to transfer rotational motion to stripping chute. The machine uses the principle of abrasion to shell maize. Model (Y=54.92+ 0.248 X1-2.68 X2 ± 1.187) obtained from evaluation reveals that shelling capacity is a function of two predictors, speed (X1) and moisture content (X2). For every unit increase in cranking speed at a particular moisture content (23.2%, 18.5% or 14%) shelling capacity increases considerably. When the experiment is run at much lower moisture content (18.5%) shelling capacity increases significantly. The machine reached highest shelling capacity (60 kg h-1.) at lowest moisture content (14%) and highest speed (120 rpm). The machine was developed at affordable cost of $61. Shelling efficiency is also a function of speed and moisture content at which it is processed. For this condition, maximum shelling efficiency is achieved at lowest moisture content possible (14%) and terminal speed of 80 rpm. Mechanical damage resulted when the speed and moisture content are inconsiderably high. The machine is suitable for use by small and medium scale processors; it can efficiently replace the manual shelling methods as it is affordable, less stressful and easy to maintain.