Development, Performance Evaluation and Economic Analysis of a Hand-Operated Maize Sheller

Abstract

Traditional maize shelling is labour-intensive, time-consuming, and often unsuitable for timely post-harvest processing by small and marginal farmers, whereas power-operated shellers may be unaffordable or dependent on unreliable energy supplies. This study developed and evaluated a low-cost, hand-operated tubular maize sheller intended to improve shelling performance while limiting kernel damage. The machine comprised a cylindrical shelling unit, interchangeable dies, a lever arm, a cob constrictor, and a stainless-steel plunger. Performance was assessed using a local maize variety at grain moisture contents of 10, 13, and 16% on a wet basis, with three replications at each level. Machine capacity, unshelled grain, mechanically damaged grain, shelling efficiency, and cleaned outlet grain were measured. The highest machine capacity, 50.00 kg h⁻¹, occurred at 10% moisture content. The most favourable overall performance occurred at 13% moisture content, where the machine achieved a capacity of 48.15 kg h⁻¹, shelling efficiency of 98.76%, cleaned outlet grain of 98.95%, unshelled grain of 3.25%, and mechanically damaged grain of 0.98%. At 16% moisture content, capacity decreased to 43.37 kg h⁻¹, while unshelled grain and mechanical damage increased to 4.29% and 1.97%, respectively. The economic assessment reported a payback period of 0.7 years. These findings indicate that the developed sheller performed most effectively at approximately 13% moisture content and may provide a practical manual shelling option for small-scale maize processing.