An expeller press is a mechanical device used to extract oil from seeds and nuts. It works by applying high pressure to the raw materials, which forces the oil out while leaving behind the solid residue, known as the oil cake. This method is commonly used for extracting oils from sources like sunflower seeds, soybeans, and canola. The expeller press operates without the use of chemicals, making it a popular choice for producing natural and organic oils. The process retains more nutrients compared to other extraction methods, such as solvent extraction, which uses chemicals to separate oil from the raw materials.