Design and performance evaluation of peg-tooth and rasp bar threshing units for Adlai (Coix lacryma-jobi)
DOI:
https://doi.org/10.15282/jmes.20.3.2026.3.0880Keywords:
Adlai Threshing, Post-harvest Technology , Agricultural MachineryAbstract
Adlai (Coix lacryma-jobi) is a nutritionally valuable grain cultivated in parts of Mindanao, Philippines; however, its threshing process remains limited by the lack of crop-specific equipment. Farmers usually depend on paddy threshers that are designed for the physical features of paddy, not Adlai, and this may lead to a drop in threshing efficiency, low output capacity, and poor grain quality. This study aimed to design, fabricate, and evaluate two threshing cylinder configurations for Adlai: peg-tooth and rasp bar. The apparatus was operated in a 2×2×2 factorial experiment with 2 cylinder configurations, 2 feed rates of 30 and 60 kg/h, and 2 cylinder speeds of 750 and 1125 rpm with 6 replicates for each treatment combination. Performance was evaluated based on threshing efficiency, capacity, and grain damage. Results showed that the peg-tooth configuration generally produced higher threshing efficiency and threshing capacity than the rasp bar configuration under the tested conditions. The highest mean threshing capacity was obtained using the peg-tooth cylinder at 1125 rpm and 60 kg/h, with 91.20% threshing efficiency and 43.60 kg/h capacity. The highest average threshing efficiency of 94.26% was obtained using the peg-tooth cylinder at 1125 rpm and 30 kg/h. Generally, mean grain damage levels remained under 5% for all the mixes of treatments. Nevertheless, the performance variations noticed should be considered as the joint impact of cylinder configuration and clearance setting.
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