A pre-cleaner cum grader is an essential processing machine used in agriculture to remove impurities and classify seeds, grains, or spices based on size, weight, and physical properties. The process begins as raw material enters the machine through a feed hopper, where an initial air-aspiration system blows away lighter debris such as dust, chaff, and husks. The remaining material then passes over a series of multi layered, oscillating or vibrating screens (sieves) with varied perforations: oversized waste (large stones, sticks, or straw) is scalped off by the top screen, while smaller impurities like sand or weed seeds drop through the bottom screen. Finally, the clean, uniform grains are separated and graded into different size fractions through specialized outlet spouts, often receiving a secondary air wash to ensure high-purity, standardized output ready for further processing or packaging.