An air-screen cleaner separates impurities by physical properties: an air stream lifts out light material (dust, chaff, leaf fragments), while one or more screens grade by size, scalping off large trash such as stems and clods and sifting out fines and broken or undersized seeds. It is the workhorse of any seed cleaning machine line and handles the bulk volume of raw-material contamination.
A magnetic separator targets one specific hazard: ferrous metal. Nails, wire, bolt fragments and machine debris routinely arrive mixed into bagged or bulk seed. These pieces are often similar in size and weight to the seed itself, so airflow and screens cannot reliably reject them — only a magnetic field can.
Each device is blind to what the other removes. An air-screen cleaner will pass a steel nut that happens to match the seed's screen fraction; a magnet will ignore stones, glass, dust and stems entirely. Running them in series — typically a magnet at intake, then air-screen cleaning, often with a second magnet just before dehulling or pressing — gives full coverage.
Metal removal is also equipment insurance. A single bolt entering a seed dehulling machine or screw press can chip rollers, score the pressing chamber and force unplanned downtime. Stones and tramp metal are likewise a fire and spark risk ahead of any seed roasting machine.
A typical sequence in seed preparation is: intake magnet → air-screen cleaner (aspiration plus scalping and grading screens) → destoner if needed → vibrating screen for final size grading → secondary magnet before the dehuller or press. The exact layout depends on seed type and how dirty the incoming material is; heavily contaminated smallholder-sourced seed in Africa or South Asia usually justifies the second magnet.
Plate magnets and drum magnets are common formats. Plate magnets mount in chutes with minimal flow restriction; drum magnets self-clean continuously, which suits higher throughputs where manual magnet cleaning would be missed during busy shifts.
When sizing a cleaning section, match the air-screen cleaner's capacity to your press line's hourly intake, specify screen decks for your main seed (peanut, sunflower, sesame, soybean), and place magnets where flow is thin and steady so metal actually contacts the magnetic face. SinoOil Machinery has supplied complete seed preparation equipment lines — cleaners, magnets, dehullers and roasters — to oil mills in 80+ countries since 2009, with ISO9001, CE and SGS certification. Contact our engineers for a cleaning-line layout matched to your seed and capacity.
Ideally both. A magnet at intake protects the cleaner itself from large tramp metal, and a second magnet just before the dehuller or screw press catches fine ferrous fragments that entered downstream. If you can only install one, place it immediately before the press, where metal does the most damage.
Partially. A vibrating screen handles size separation well but has no aspiration, so light impurities like dust and chaff pass through. Many lines pair a vibrating screen with an air aspirator, which together perform the same function as an integrated air-screen cleaner. See our seed preparation equipment range for both options.
A screw press squeezes seed against a hardened cage at high pressure. Even a small steel fragment can score the worm shaft and pressing bars, reducing oil yield and forcing costly part replacement. Combined with shells — which are abrasive and absorb oil — uncleaned seed shortens press life significantly.
SinoOil engineers size the right pretreatment equipment for your capacity — free plant design included.
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