The oil press refers to a kind of device that can, by means of external mechanical force, squeezes grease from oil through raising the temperature and activating oil molecules.
Classification
Oil presses can fall into household oil press, hydraulic oil press, screw oil press, new hydraulic oil press, high efficiency fine oil filter press and automatic oil press.
What we introduced now is screw oil press. Compared to other types of oil presses, a screw oil press has a high oil capacity, good cost performance and simple operation although the oil quality is not as good as that of other oil presses. (A hydraulic oil press only need a small driving force, which can be drove by both three-phase and household electricity. The oil is clear but the output is low. So a hydraulic oil press is more suitable for expressing high-end oil such as sesame oil and walnut oil.)
Expression Method
There are two methods for extracting edible oil from plants, which are chemical extraction and physical extraction. Normally they are also known as lixiviation method (chemical) and expressing method (physical).
With a long history, the expression method has a relatively simple process. After steaming and frying raw material, it can express oil from the material by means of mechanical method. The traditional expression method requires strenuous manual labour and the content of residual oil is quite high, wasting extremely valuable raw material. The modern expression method can complete industrial automatic operation, but it neither solve the problem that the content of residual oil is high.
There is cold press and hot press in terms of the pre-treatment of raw material. The cold press refers to the process where raw material, without drying, frying and steaming, is directly put into the oil press for extracting oil. The oil produced by cold press is more bright with a relatively light color, but it has a low oil yield and no rich, nice and mellow flavor. The hot press refers to the process where raw material is dried before expression to lower moisture in the material and enhance the activity and mobility of oil molecules so that it can improve the oil yield and ensure the rich flavor of oil. But the oil has a darker and blacker color due to its chemical compositions are destroyed.
Press Technology
1. Conventional production process: raw material --- steam and fry --- press --- crude oil pressed by machine
2. Special oil production process: oil seeds --- fry oil seeds --- press --- filter --- perfumed oils and fats
3. Special oil material production process: oil seeds --- cold press for whole oil seeds --- filter --- oils and fats produced by cold press
The process that expresses oil from raw material
When the raw material comes into the oil press, it will rotate along with the barrel and pressure will increase. With the extrusion of oils and fats, the seeds are constantly squeezed, and the pressure generated by material particles that are in direct contact with each other can cause the deformation of seeds and particularly the adhesion at the broken place of oil film. Hence, the material is not loose anymore but can be shaped after being squeezed out of the barrel, known as oil cake. Under the dual action of temperature and pressure, the protein continuous to be spoiled, influencing the plasticity of the material. In conclusion, only the proper denaturation of protein can ensure the best extraction effect.
Advantages
No chemical additive is added in the production process by adopting this device.
1. Simple and convenient operation;
2. High oil yield and low pressing cost;
3. High quality oil with rich nutrition;
4. Optimized raw material is safe and reliable.
Parameters
| Model | Pressing Level | Power | Oil Filtering Method | Length of Bar Cage | Processing Capacity | Package Size | Weight |
| GY-301 | Five | 7.5KW | Centrifugal Type | 766mm | 3 tons/day | 2290x750x1850 | 0.5 Ton |
| GY-302 | Five | 7.5KW | Positive Pressure Type | 766mm | 3 tons/day | 2290x750x1850 | 0.5 Ton |
| GY-401 | Five | 7.5KW | Centrifugal Type | 766mm | 4 tons/day | 2290x750x1850 | 0.5 Ton |
| GY-402 | Five | 7.5KW | Positive Pressure Type | 766mm | 4 tons/day | 2290x750x1850 | 0.5 Ton |
| GY-501 | Six | 15KW | Centrifugal Type | 976mm | 5 tons/day | 2550x820x1900 | 0.6 Ton |
| GY-502 | Six | 15KW | Positive Pressure Type | 976mm | 5 tons/day | 2550x820x1900 | 0.6 Ton |
| GY-503 | Six | 15KW | Vane Type | 976mm | 5 tons/day | 2550x820x1900 | 0.6 Ton |
Note: The above parameters belong to oil presses, excluding filtration
Precautions
1. Check the lubricating condition after every 50 hours of work. The oil cup on the reduction gearbox shouldn’t lack of oil. The dry grinding is strictly prohibited.
2. Prevent dusts and other impurities from coming into each lubricating part. Check the quality of the engine oil in the reduction gearbox annually, and replace all engine oil
if it is spoiled.
3. When the yield reduces and the production of oil cake and oil is abnormal, take out the screw shaft to check the wear of the screw, cage bar, oil cake outlet head and oil cake outlet. The wear parts should be replaced in time.
4. Clean the residual oil cake inside the machine after every work. Wipe dusts and oil dirties off the machine surface.
5. When it need be kept for a long time after production season, perform a maintenance for it. Disassemble the screw, cage bar, oil cake outlet head for cleaning and smearing oil, and then re-assemble the machine. Place it in a dry place.
6. After each press, the screw shaft should be removed for cleaning residue, and the rotating mouth should be swabbed with a dry cloth and cotton swab stick to prevent blockage.
Common Failures
I. The moisture in the raw material is too low.
1. There is abnormal sound in the barrel of the oil press making the whole oil press vibrate.
2. Oil cakes can’t come into firm solids, which is dark brown with focal spot.
3. The current loaded by the driving motor is higher than 30 amp.
4. The position of the oil outlet moves to the direction of the cake outlet. The smoke rises from the cake outlet, the production of oil reduces and oil color becomes dark brown.
5. If the above phenomenon lasts too long, it will cause tremendous mechanical damage accidents. At this time, it’s necessary to immediately reduce the steam pressure, increase the direct steam injection amount in the upper steam cylinder, close the feeding door, reduce the feeding to the barrel, increase the thickness of the cake. When the load of the oil press gradually decline, adjust it to resume the normal working condition.
II. The moisture in the raw material is too high.
The higher content of moisture in the raw material can generate the following phenomena:
1. There is less feeding and even no feeding, or the material rotates along with the shaft.
2. Oil cakes are soft and loose containing too much moisture. Cakes come out with oil. Or cakes rotate along with the shaft.
3. The motor load reduces and the working current is lower than 20 amp.
4. The oil yield reduces. The oil white and foamy. The position of the oil outlet moves to the direction of feeding. When the above conditions happen, instantly improve the indirect steam pressure, reduce the injection amount of the direct steam, and add some residual cake into the feeding port until the oil press resumes the normal working condition.
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