Expeller pressing (also called Expired oil pressing ) is a mechanical method for extracting oil from raw materials trademarked by Anderson International Corp. Mr. Valerius D. Anderson founded the Anderson VD Company in Cleveland, Ohio in 1888. In 1900, Mr. VD Anderson created the first successful ever-operated Expeller press.  The raw materials are squeezed under high pressure in a single step. When used for the extraction of food oils, nuts , seeds and algae, which are supplied to the press in a continuous feed. As the raw material is pressed, friction causes it to heat up; in the case of harder nuts, which can be found at 120 ° F (49 ° C).
An expeller is a screw-type machine that mainly presses oil seeds through a barrel-like cavity. Other materials used with an expeller press include goal arent limited to meat by-products, synthetic rubberand animal feeds. Raw materials enter one side of the press and waste products exit the other side. The machine uses friction and continuous pressure from the screw drives to the material. The oil seeps through small openings Afterward, the seeds are formed into a hardened cake, which is removed from the machine. 140-210 ° F (60-99 ° C). Some companies claim that they use a cooling apparatus to reduce the temperature of the product. 
Expeller processing can not remove every last trace of liquid (usually oil) from the raw material. A significant amount remains trapped inside the cake left over after pressing. In most small-scale rural situations this is of little importance, as the cake that has left behind the eyes of the family, in the manufacture of secondary products, or for animal feed. Some raw materials, however, do not release oil by simple expelling, the most notable being rice bran . In order to remove oil from expansions, it is necessary to use solvent extraction .
The earliest expeller presses used a continuous screw design. The compression is one of the screws of a screw conveyor -that is, the helicoid flighting started at one end and ended at the other.
Valerius Anderson invented the interrupted screw design and patented it in the year 1900.  Anderson observed that in the continuous flighting arrangement of a compression screw, there are tendencies for slippery materials or to co-rotate with the screw or to pass through minimal dewatering. He wrote that ” brewers ‘ slops, slaughterhouse refuse” and other “soft and mushy” materials dewater poorly in continuous screw presses.
His invention of putting interruptions in the flight of a compression screw. It was much like having a hanger bearing a screw conveyor: there is no flighting on the shaft at that point, so material tends to stop moving and pile up. It is only after having accumulated in the gap that the downstream flighting catches material. When this happens, the material is forced along its way. The result is better dewatering and thus a more consistent press cake.
After the 1900 patent, a major improvement was made with the addition of resistor teeth. Fitted into the gaps where there is no flighting, these teeth increase agitation within the press, further diminishing co-rotation tendencies.
As the years went by, the applications of the cut-off design were expanded beyond slippery and slimy materials. This paper is a work in progress and has a constant working relationship. If the condition is diminished, squeezing would have diminished until it was inadequate for proper moisture removal. At the same time, if the consistency increased, the press could jam. To counteract these tendencies it was necessary to build a very heavy press, frequently with an expensive variable speed drive.
In contrast, it was found that the interruptions in the flight of the Anderson screw would provide cushion within the press. If consistency went down, compression was still effective. A plug of sufficiently solid material had to be built at each interruption before the solids could progress towards the discharge. This self-correcting performance prevents wet material from purging at the cake. It is achieved without varying the speed of the screw.
The economic advantages of these characteristics are not limited to those being used as thinning machines. Examples would be alfalfa , corn husk , and more recently, paper mill fibers.
- Algacea oil extraction
- Dewatering screw press
- Oil mill
- Jump up^ http://www.andersonintl.net/index_files/History.htm
- Jump up^ Spectrum Expeller Pressed vs. Cold Pressed
- Jump up^ Twin screw press with interrupted Flights – US Patent 6550376 Description