Design and fabrication of a motorized rice hulling machine

Rice is one of the most important cereal crop in the world. This paper present the design and performance evaluation of a rice hulling machine fabricated for removing chaffs from paddy rice as the consumer’s demand for rice requires the most hygienic, easy and less time consuming process. The design was segmented into the hopper and housing (processing) unit, the frame support and the power transmission unit. The housing unit consists of the upper and lower body where the sieve, hulling blade and cylinder is enclosed. The machine is powered by a 3.0 H.P. 950 rpm electric motor via a V-belt mechanism which deliverers the power requirement to the shaft on which the hulling cylinder is mounted. The hulling cylinder presses the paddy rice against the hulling blade to remove the chaff. The paddy rice is fed into the housing unit for processing through the machine hopper. The probability failure of the machine during loading has been minimized by proper material selection and using a factor of safety of 4 in the design process. The machine was designed to process about 8 kg of rice for small scale production. Performance evaluation of the machine shows that its efficiency is within the range of 83 to 88%, the hulling capacity is within the range of 22 to 25 kg/h and the maximum efficiency is at 5 kg paddy rice hopper loading which is about 60% of the hoppers’ volume. Key words: Rice, hulling, dehusking machine, paddy, fabrication.