Design, Fabrication, and Performance Evaluation of BRRI Compact Rice Mill

Abstract

In the past, smaller rice mills such as the Engelberg huller mill were frequently utilized. But caused by technological developments, larger rice mills with rubber roll huskers have shown promise, however at a high initial cost. The BRRI compact rice mill is designed to improve the rice milling system's efficiency. This single-pass hulling machine processes paddy into polished white rice by sequentially lifting, cleaning, de-husking, polishing, and grading the rice into head and broken categories using rubber rollers, blowers, and a size grader. Additionally, husk and bran are separated during the milling process. The rubber-roller spring system, main body shell, and machine base structure were validated using finite element analysis (FEA). From the simulation study, the machine's maximum displacement experienced 0.13 mm, and its base structure safety factor was 6.56. In addition, the FEA study was carried out to analyze the fatigue life, fatigue damage, safety factor, and fatigue sensitivity for the machine rigidity. The analysis showed a deformation of 2.43 mm and a safety factor of 1.74 for the main body shell, while the spring system demonstrated a safety factor of 2.93. These findings confirm the machine's strength, durability, and safe performance under applied loads. The machine is developed using locally available materials from the Bangladeshi marketplace. Its design is created using computer-aided modeling (3D and 2D) with all necessary technical specifications for future manufacturing. The selected materials ensure optimal performance for the compact rice mill. In power transmission, three B105 belts, each with a pitch length of 2667 mm, were used to transfer mechanical power from the main motor pulley to the polisher pulley; moreover, the adjustable motor base prevented slippage during the operation period. The rice milling machine was working at 0.02 kWh per kg of rice, with an 850 kg hr^-1 capacity for hulling. The milling recovery was only 65%, but husking was better at smaller roller clearances. Thus, in the waters of enhanced milling recovery and lesser power consumption exists the potential for the BRRI compact rice mill to be a substitution for the expensive-type rice mills.