The mechanical extraction operation is generally similar to the pretreatment workshop, like pretreatment, many oil presses are fixed in the same building for pressing. In the press plant, the oilseed is subjected to extremely high heat and pressure to mechanically press the oil out of the oleaginous cells. A typical pressing process includes steaming, pressing, cooling and finishing of the cake and filtering of the oil.As with most processes, the operation and layout of nearly every plant is different. The following describes a general pressing operation, and the reader is aware that there are many variations to this system design. In this general operation, the pressed kernels from the flaking machine enter a vertical layer steamer wok with stirring, where they are heated to denature the protein, and the hot kernels after steaming and frying enter a mechanical press, where they are steamed and fried Intensified mechanical pressure removes about 60% of the oil (approximately 90% for full press operations), the cake passes through end baffles where high friction is applied, and the cake is toasted, pressed and often very hard. The squeezed oil flows out through the drain bar of the press. After pressing, the cake is crushed and cooled, and the pre-pressed cake is usually sent to the solvent leaching workshop for final oil removal. If the solvent leaching is not economically acceptable, the press plant has to squeeze out a higher proportion of oil (the so-called full press operation), and the cake is used directly as animal feed. As the material is subjected to high heat during operation, urease inactivation and protein denaturation occur naturally, making the product suitable for feeding purposes. Oil from mechanical pressing operations usually contains a large amount of fines, which enters a screened storage tank and is removed in a leaf or plate and frame filter press. This is done before the crude oil is sent to the refinery. 

The pressing process can be varied in many ways. As mentioned above, the extruder can be used before pressing, but in some cases it can be used after pressing to provide uniform material to the solvent leaching section with agglomerated powder. The material entering the steamer can be green, or the pressed cake can be rolled to obtain rolled oil.