Design Modification and Fabrication of a Dual-Purpose Rice Processing Machine

Abstract

This study presented the design, fabrication, and performance evaluation of a dual-purpose rice processing machine that integrated threshing and milling operations into a single unit to address the inefficiencies of conventional post-harvest rice processing. The machine was designed using standard mechanical design principles and fabricated with locally available materials to ensure affordability, durability, and ease of maintenance for small- and medium-scale rice processors. A 1.5 hp electric motor served as the prime mover, driving both the threshing drum and milling rollers through a belt and pulley transmission system. Performance evaluation was conducted through a series of preliminary and formal tests using paddy rice samples. Experimental results showed a threshing efficiency of 66%, milling efficiency of 69.69%, and rice husk recovery of 39.6%. When operated as an integrated single-pass system, the machine achieved an overall operational efficiency of 46%, producing 2.3 kg of milled white rice from 5.0 kg of paddy. Although this overall efficiency is moderate and lower than that of many optimized conventional rice processing systems, it remained acceptable for a low-cost prototype and demonstrated the feasibility of integrating threshing and milling in a compact unit. These results highlighted the potential of the machine to reduce processing time, labor, and equipment cost. However, further optimization particularly in grain transfer mechanisms, threshing consistency, and milling clearance adjustment is required to improve performance. It is therefore recommended that future designs should focus on improving component alignment, enhancing separation efficiency, and conducting extended field testing under varying moisture and load conditions to achieve higher overall efficiency and reliability. Overall, the developed machine offered a practical and cost-effective solution for improving local rice processing and enhancing food security in rural communities.