A screen separates material by size difference, so the right mesh is always defined by your seed versus your impurities — never by the seed name alone. A deck sized for peanuts in shell would let sesame pour straight through with the trash, and even within one crop, kernel size shifts by variety, growing region and season. The impurity profile matters just as much: stems, pod fragments and stones run larger than most oilseeds, while sand, dust and broken kernels run smaller.
That is why reputable suppliers quote a selection logic rather than one fixed mesh number. The practical question is: what is the largest size your good seed reaches, and what is the smallest? Those two boundaries define both decks of a vibrating screen.
Most oilseed cleaning screens use two decks working in opposite directions. The top deck (scalping deck) has openings slightly larger than your largest good seed: kernels fall through, while stalks, pods, leaves, string and oversized stones travel across the deck and discharge over the end. The bottom deck (sand deck) has openings slightly smaller than your smallest good seed: clean kernels ride over it to the outlet, while sand, soil, dust and small broken pieces drop through into a fines collection point.
Good seed therefore exits as the middle fraction — too small for the top deck, too big for the bottom one. If you see whole kernels in the fines or trash streams, the openings are wrong for that lot, not the machine.
The reliable method is to test a sample of your actual seed lot with hand sieves: choose a top-deck opening that passes essentially all sound kernels, and a bottom-deck opening that retains essentially all of them. Because lots vary between harvests and origins, screens with interchangeable deck frames are typically worth the small extra cost — a mill handling peanut, sesame and sunflower in rotation simply swaps decks rather than buying three machines.
Screening alone cannot remove light impurities that happen to match the seed's size, such as empty hulls and chaff — those separate by density, not size. That is why a complete seed cleaning machine pairs the screen decks with air aspiration, and many lines add magnetic or destoning stages for metal and heavy grit.
Sand and stone left in the seed act as an abrasive inside every downstream machine — dulling sheller blades, scoring roaster drums and accelerating wear on screw press components. Cleaning is therefore the first stage of any properly designed seed preparation line, ahead of dehulling and roasting, and it directly affects oil quality: dusty feed darkens crude oil and increases filtration load.
SinoOil Machinery has supplied factory-direct cleaning, shelling and roasting equipment to oil mills in 80+ countries since 2009, with ISO9001, CE and SGS certification. If you can share your seed type and a description of your typical impurities, our engineers will recommend deck openings and a matching vibrating screen configuration — contact us here.
Only partially. One deck can remove either oversize trash or undersize fines, but not both in one pass. A two-deck vibrating screen — scalping deck on top, sand deck below — removes both fractions simultaneously, which is why it is the standard configuration for oil mill cleaning sections.
Yes. These seeds differ greatly in size, so each needs its own pair of deck openings. Mills that process multiple crops typically order a screen with interchangeable deck frames and verify openings against a hand-sieved sample of each new lot.
Light impurities that match the seed's size cannot be separated by mesh openings — they differ in density, not size. Adding air aspiration to the cleaning machine removes chaff, empty hulls and dust that pass over the decks with the good seed.
Indirectly but significantly. Removing stones and sand protects the screw press from abrasive wear, and thorough cleaning prepares seed for dehulling — and because shells absorb oil during pressing, removing them raises extractable yield and improves crude oil quality.
SinoOil engineers size the right pretreatment equipment for your capacity — free plant design included.
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