What are the principles of air separation and screening in a cleaning machine?

The air-screen cleaner is a high-efficiency cleaning device that integrates air separation and screening functions. Its core purpose is to remove light impurities, heavy impurities, and classify materials, and it is suitable for the impurity removal needs of most granular materials.

The core principle of air separation is to utilize the difference in density (or aerodynamic properties) between materials and impurities, while the core principle of screening is to utilize the difference in particle size (particle diameter, shape) between materials and impurities.

I. Principle of Air Separation
Air separation is based on “aerodynamic separation,” relying on the difference in the forces exerted by airflow on different materials to achieve separation.

A fan generates a directional airflow. The buoyancy (or air resistance) of the airflow on lighter objects accounts for a higher proportion, while the force exerted on heavier objects accounts for a lower proportion.

When a mixture of materials (such as rapeseed and straw fragments) passes through the airflow zone, lighter impurities (straw, shriveled grains, dust) are carried away by the airflow, while heavier materials (plump grains) maintain their original trajectory because gravity is greater than the force of the airflow, thus achieving separation.

The separation effect can be ensured by adjusting the airflow speed to accommodate the density differences of different materials.

II. Principle of Screening
Screening is based on “particle size classification,” relying on the size of the sieve aperture to separate materials from impurities.

The sieve has a fixed aperture, allowing only particles smaller than the aperture to pass through, while particles larger than the aperture are blocked.

When materials move (vibrate or tumble) on the screen surface, materials that meet the particle size requirements (such as qualified rapeseed) pass through the screen holes and become the undersize; impurities larger than the aperture (stones, large clods of soil) remain on the screen surface and are discharged from the impurity discharge port.

Multi-layer screens can achieve multi-stage grading. The screens with different apertures decrease in size from top to bottom, separating large impurities, qualified materials, and small impurities respectively.