Removing light foreign material with aspiration
A vibrating screen separates by size. Leaves, stalks and dust are often the same size as the product, so they are taken out by air instead.
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Two separations in one machine
The product falls onto a perforated deck. Heavy foreign material such as stones and soil is separated here by the screen. Above the deck an aspiration unit draws air across the product stream; light material such as leaves, stalks and dust is carried into the air flow and discharged outside the machine.
Where it is used
This arrangement is used on raisins, dates, beans, chickpeas, sunflower seeds and pumpkin seeds, where the raw material arrives with field debris that the screen alone cannot remove.
Air flow and product
The air speed is set so that it lifts the light material but not the product. The product is spread thinly over the deck by the vibration, which exposes the debris to the air stream. A version with air blown from below the deck moves the debris into the aspiration path faster.
Screen panels and access
The screen panels are stainless steel and quickly removable, so a panel for a different product or opening size can be fitted without tools that need a workshop. Maintenance covers give access to the deck and the air duct for cleaning.
Drive
The deck is driven by two vibration motors; the aspiration fan has its own motor. The two systems are set separately: vibration for conveying and screening, air flow for the light fraction.
Related: vibrating screen, maintenance.