Oil seeds need to be cleaned to remove plant stems, mud and sand, stones and metals, leaves and foreign material before being extracted. Oil seeds without careful selecting will speed up the wearings of the accessories, and can even lead to damage of the machine. Foreign materials are typically separated out by a vibrating sieve, however, some oilseeds such as peanuts may contain stones which are similar in size to the seeds. Hence, they cannot be separated by screening. Seeds need to be separated from stones by destoner. Magnetic devices remove metal contaminants from oilseeds, and hullers are used to de-hull of oilseed shells like cottonseed and peanuts, but also in crushing oilseeds such as soybeans.
