Onion size grading machines are specialized equipment used in agriculture to classify onions according to their size. They significantly improve the commercial value and processing efficiency of onions. Common types include roller type, bar type, and weight-based grading type, and they are widely used in large farms, vegetable processing plants, and food distribution centers. The following is a detailed introduction:

Roller-type grading machine: This is the most widely used type. The grading bed consists of multiple rollers, all driven forward in parallel by rolling bearings, with the center distance between the rollers gradually increasing. As the onions move forward with the rollers, onions matching the gap size fall sequentially onto the corresponding conveyor belt below, achieving continuous grading from small to large. The graded onions can then be directly connected to the bagging and sealing device for subsequent processing.

Drum-type grading machine: Onions are fed into a drum with grading apertures via an elevator. As the drum rotates, the onions slowly roll along the inclined drum wall. The apertures on the drum are designed in ascending order, and onions of the appropriate size fall sequentially into the corresponding receiving troughs, finally exiting from the discharge port. This type is particularly suitable for round and oval onions, and can also be customized to meet different size requirements.

Weight-based grading machine: This type of equipment focuses on the relationship between weight and size, equipped with a high-sensitivity dynamic weighing sensor. As the onions move on the conveyor belt, the equipment can complete weight recognition within 0.5 seconds and then grade them according to a preset weight range. It has high weighing accuracy, with an error that can be stabilized within ±1g, and can automatically remove deformed fruits, effectively avoiding the error problems of manual sorting.

Precise grading with low loss: The rollers and drums are typically polished, and some machines use food-grade wear-resistant soft rubber conveyor belts, reducing bumps and knocks during the grading process and lowering the loss rate to below 2%. The grading aperture or weight range can be precisely set; some models can divide the onions into 5 grades, and some even support 4-12 custom grading grades, ensuring uniform size of onions within the same grade.

High adaptability and customizability: In addition to onions, most models can also be used for grading root vegetables such as potatoes, garlic, and sweet potatoes. Structurally, they can be designed horizontally or inclined to suit different workshop spaces, and the grading range can be adjusted as needed, for example, to accommodate small onions (30-50mm) and large onions (80-110mm). The machine body is mostly made of 304 food-grade stainless steel and has IP65 waterproof performance, making it suitable for muddy field environments and processing plant washing scenarios.

Highly efficient, convenient, and easy to maintain: Different models have significantly different processing capacities. Smaller machines can process 2-10 tons of onions per hour, while larger machines can process 15-30 tons, far exceeding the efficiency of manual sorting. Operation is facilitated by a simple control system or touchscreen, allowing for real-time parameter setting and production data viewing. Key components feature a modular design, with conveyor belts and hoppers that can be quickly disassembled for easy cleaning and maintenance.