Students make lotus seed peeling machine

Product of Duong Chi Bao and Pham Hoai Bao, 4th year students of the Faculty of Engineering Technology and Manufacturing, with the goal of increasing processing productivity and reducing labor compared to the manual method of peeling lotus seeds.

Lotus is grown in many localities across the country such as Dong Thap, Long An, Tien Giang, Hanoi, Hung Yen… However, lotus seeds are currently mainly peeled manually, with low productivity. A worker peels only 7 – 8 kg per day, with a rental cost of about 30,000 – 40,000 VND per kg. The market currently has many imported lotus peeling machines, but the price is high, about 150 million VND each. “With household production scale, high investment costs will be a barrier, making it difficult for people to access,” Chi Bao said. This is also the reason the team researched a lotus seed peeling machine.

Since March, two students came up with the idea of ​​designing a 3D automatic lotus seed peeling machine. After 4 months, the product was completed from the original design. The machine operates based on a manual peeling mechanism, which means using a knife to cut circles on the surface of the grain, then separate the shell. Lotus seeds are positioned in a fixed direction by a conveyor belt fitted with rollers, then fed into the cutting knife system. After cutting, the seeds are transferred to the pressing area, creating a force to separate the shell and seeds. Centrifugal blowers blow just enough air to separate the shell from the seeds. The heavier particles will fall into the collection cavity and into the container.

According to Hoai Bao, previously researched lotus seed separator products mainly used heat belts to bring lotus seeds to the cutting blade. This method has the disadvantage that the lotus seeds cannot be fixed, causing them to be stuck in one position, affecting performance when it comes to cutting.

With the roller conveyor design, lotus seeds are brought evenly to the cutting blade, helping to overcome the above drawback. Bao said that the most difficult process of designing a conveyor belt is making the lotus seeds lie in the right direction. When the user puts lotus seeds into the hopper, the seeds that are not in the right position will be blocked by the roller and pushed back in the opposite direction until they are in the correct direction to pass through the conveyor belt.

In actual testing, the machine achieved a productivity of 24.6 kg per hour, shell cleanliness reached 82% with fresh lotus seeds harvested in less than a day. If fresh lotus is stored at a temperature of 2 – 4 degrees Celsius in the refrigerator for 5 days, the machine will achieve a productivity of 20 kg per hour, and the shell cleanliness will reach 70%. With lotus seeds not stored for 5 days, the machine only achieves a productivity of 9.5 kg per hour, with a shell cleanliness of 40%.

According to the research team, lotus seeds need to be shelled immediately after being harvested, because if left for a few days, the shell will become tough and the shelling efficiency will be significantly reduced. “Farmers often peel the skin right after harvesting. The reason is that separating is easier and ensures lotus seeds retain their freshness during later processing,” Hoai Bao said.

Seeds that cannot be deshelled by the machine are often old, have high hardness, and have uneven grain sizes. Currently, the group’s products have two conveyor belts corresponding to two peeling knives. The machine price is expected to be from 12 – 15 million VND, suitable for the majority of household-scale farmers. The group said that it can be developed into multiple conveyors with larger machine sizes to increase peeling productivity to serve the needs of large-scale manufacturing enterprises.

Engineer Truong Cong Nam, Faculty of Engineering and Technology, Mekong University (Instructor), said that the lotus peeling machine product is a continuation of the lotus peeling machine of previous students. After completing the two machines, the group plans to develop a lotus seed processing line from the stage of separating lotus seeds to seeds, serving automation in agricultural production.

According to engineer Nam, the machine’s limitation is that the grain size is uneven and the peeling ability is not stable. He suggested that the team need to evaluate the sufficient cutting force or use additional glide knives to overcome this problem.

Associate Professor, Dr. Nguyen Ngoc Lam, former Head of the Institute of Electronics – Informatics – Automation Research, Ministry of Industry and Trade, assessed that the group’s products have structures that are not too complicated and are easy to operate, so they can be applied. right. However, Associate Professor Lam commented that the product is currently powered by a motor, using direct electricity, so when the current changes in the conveyor system, the machine’s cutting knives are affected. He suggested that the team could design an inverter to help protect the machine as well as keep the operating mechanisms more stable.