The anatomy of a commercial oil press machine

A commercial oil press machine is the heart and soul of any oil extraction operation. You may be involved in edible oil extraction from seeds, nuts, fruits, or some other plant-based material. Maybe you extract non-edible oil from plants like jatropha for the oleochemical or biodiesel industries. You could be extracting oils from common oil-bearing materials like sunflower seeds, peanuts, olives, or niger seeds or from rarer sources like grape seeds or Brazil nuts. Almost always, oil press machines will form the foundation of your operations.

What is a press oil machine?

Oil press machines, alternatively called press oil machines, are essential pieces of equipment in the oil processing industry. They use mechanical or hydraulic pressure to separate oilseeds (or nuts or fruit) into oil and meal.

Oil press machines differ in size or capacity. The capacity of a press oil machine is usually expressed in terms of the weight of raw material that it can process per hour. A simple commercial oil press machine may have a capacity of anywhere between 3 kg and 100 kg (6.6 lb to 220 lb) of input material per hour. More complex commercial oil press machines may have much higher per-hour capacities.

The anatomy of a commercial oil press machine

Typically, a screw oil press machine for industrial use will be constructed with the following components: seed hopper, gearbox, expeller screw, barrel, oil canals, slots or screens, press head, and press nozzle.

The seed hopper is usually a metal structure. It directs the raw material, i.e. the oilseeds or nuts, into the press. The gearbox, or the gear reduction unit, is responsible for converting the speed and torque of the motor into appropriate settings for the press oil machine. The expeller screw is where the magic happens - the screw rotates within a cylindrical cage to pressurise the oil-bearing material. The resultant friction may result in temperature increases, which may add to the high-pressure setting, aiding in oil extraction. The screening surface permits the extracted oil to seep through while keeping residual material moving through the machine, from where it is removed as cake or meal. The metal frame connects all these components and provides support for the high pressure and temperature conditions generated in the system.

Types of commercial oil press machines

The system described above is a screw press oil machine. It is the most commonly used commercial oil press machine, but not the only kind. While screw presses and similar cage presses use the principles of mechanical pressure to compress raw materials and extract oil, the other type - hydraulic presses - uses liquid as a medium to pressurise the material and obtain oil.

Hydraulic presses are more advanced, efficient, easy to control, expensive, and give higher output. A liquid, generally oil, is used to transmit force from one point to another. This force generated in a pump is transferred to a piston or other such component to exert force on the raw inputs. The oil extracted using this method is also usually of higher quality as less heat is generated.

Regardless, screw oil press machines are more widely used for plant-based oil extraction. With their simple mechanical design, fairly low maintenance requirements and capacity for continuous operations, this isn't surprising. Screw oil press machines also provide higher oil yield. On the downside, more heat is generated if a commercial oil press machine uses the screw mechanism. However, since most edible oils are heated in the process of cooking, this isn't a problem when producing cooking oils.

How do screw oil press machines work?

In a commercial oil press machine, the raw material - prepared sunflower seeds, groundnuts, shea nuts, palm fruit, palm kernels, or any other appropriately prepared input - is fed into the system through the hopper. A screw press oil machine comprises a high-pressure cylindrical chamber through which the raw material moves. As it moves, friction and heat are generated, adding to the pressure of the chamber to squeeze out the oil. The expelled oil seeps through a slot, screen, or filter while residual fibres and solids move along the system. Under the pressure of the press oil machine, these solids form a hard cake, which is removed from the machine and used to make high-protein animal feed or other useful substances. If the cake still has a high oil content, solvent extraction may be used to extract it. Meanwhile, the clear extracted oil is directed towards an oil refinery, where it may be bleached, deodorised, and/or refined using other relevant techniques.

Factors affecting oil press machine industrial operations

The efficiency of oil press machine industrial operations is affected by more than just the machine itself.

Seed type: The oil yield, or amount of oil that can be extracted from a particular raw material, varies by seed type. For instance, in canola oil extraction, oil equal to about one-third of the seed weight is obtained. Hemp seeds, too, have an oil content of only about 25 to 30%. Meanwhile, groundnuts have a relatively high oil content of 45 to 52%. So, while the size of the commercial oil press machine will determine its capacity in terms of oilseed processing capacity, the oil yield will be determined by the type of oil-bearing input used.

Seed quality: Seeds harvested either too early or too late will result in oil with an unwanted flavour, undesired chemical characteristics, or even toxic qualities. Improper harvest and storage can also result in low-quality seed that has developed mould due to its high moisture content. Low-quality seed can thus hamper oil press machine industrial operations, resulting in poor yield in terms of quality and quantity.

Moisture content: Oil-bearing seeds that are too moist will result in meal that is gummy. They will often not even produce oil as they move through the screw press. On the other hand, if the moisture content is too low, the temperature of the press head can increase significantly and lower the oil yield. For every oilseed, moisture content should be optimal (for example, 6 to 8% for canola) to ensure oil press machine industrial operations proceed as desired.

Pressing temperature: A commercial oil press machine usually has a temperature control setting. This setting can have two functions: one, to heat the system up to the temperature at which a particular oilseed expels oil best and two, to cool the system down if the oil manufacturer wants to produce cold-pressed oil. In either case, the pressing temperature will affect the nature of the machine's operations and the characteristics of the oil produced.

Press settings: Many commercial oil press machines are designed to be versatile - they can be used to expel oil from plant-based materials of different shapes, sizes, and types. However, to get the best out of every kind of oil-bearing material, it is best to adjust certain press settings when you have the option. These settings include the distance between the press head and the screw end, the press speed, the diameter of the hole through which the meal is expelled, and the type of screw. Finding just the right combination of settings may involve some amount of trial and error; contacting your oil expeller manufacturer can help you gain some insight on what will work best.

This introduction to the world of commercial oil press machines offers basic information about the structure and functioning of these integral pieces of equipment. If you are looking to invest in oil press machine industrial operations, you could also gain some insight from these articles about choosing the best press oil machine, navigating the oil expeller market, and paying the right price for your expeller press.

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