Design, Development and Performance Evaluation of a Seed Paddy Cleaning Machine

Rice (Oryza sativa L.) is the staple food crop in Sri Lanka occupying 34% of the total cultivated area. Seed paddy production is one of the major economic activities in the paddy sector, which is fully mechanized only at the large-scale level. Unavailability of an affordable mechanical solution is a big barrier for entering small and medium scale producers in to the seed paddy industry. Therefore, the aim of this study was to introduce an efficient and affordable electrical motor driven small or medium scale paddy cleaning machine for seed paddy production. The main components of the machine are paddy sieving unit, blowing unit and stone separator. According to the variety of paddy, the sieve size of the sieving unit can be changed. The performance of the machine was evaluated using paddy samples with purposely added light and heavy impurities such as straw particles and different sized stones. The suitable speeds for the better operation of sieve, separator and blower were 90, 200 and 960 rpm, respectively. The separation percentages of the large, light, and same size impurities were 96%, 74%, and 86%, respectively. The effective capacity of the machine was 252 kgh-1 with 79% mechanical efficiency. Based on the overall satisfactory performance, the newly built paddy cleaning machine can be recommended to small and medium scale paddy farmers in Sri Lanka. The machine can be further developed with a magnetic separator for removing iron particles.