| Problem | Causes |
|---|---|
| Heavy oil flow along the cage center and discharge end, instead of feed section. | Expeller is not getting sufficient feed. |
| Cake contains more oil contents. | 1. Expeller is not getting sufficient feed. 2. Improper Cooking. 3. Increased inter spaces between the bars. 4. Insufficient fibrous matter or binder in the meal. 5. Very dry seed. 6. Excess moisture in the seed. 7. Discharge of heavy foots. 8. Design of the expeller. 9. Wrong setting of worms. 10. Immature seed. 11. Worms are worn out. |
| Heavy wear and tear of the worms, knife bar and machine. | 1. Presence of sand, mud, stones in the feed material. 2. Presence of iron or metallic pieces. 3. Too dry seed is fed. 4. Running the machine in choked condition. |
| Low yield of oil. | 1. Present of impurities in the feed material. 2. Improper cooking. 3. Excess of moisture in the seed. 4. Heavy discharge of foots through cage. 5. Presence of damaged seed in the feed material. 6. Design of the expeller. 7. Wrong setting of worms. 8. Immature seed. 9. Worms are worn out. |
| Heavy Discharge of foots. | 1. Excess moisture in the cooked meal. 2. More inter spaces in cage bars. 3. Breakage of cage bars. 4. Low fibrous material. |
| Improper Cake. | 1. Improper cooking. 2. Cooked material contains excess moisture. 3. Blockage of inter spaces in cage bars. 4. Too dry feed material. |
| Material refuses to slide. | 1. Cooked material is too dry. 2. Choking of cage. 3. Improper spaces used in the cage. |
| Oil is not clear. | 1. Improper cooking. 2. Excess moisture in cooked meal. 3. Low cooking temperature. 4. Immature seed. |
| No oil coming out of the expeller. | 1. Feed material is very soft and smooth. 2. Feed material is deficient in fibrous material. 3. Material is over cooked. |
| 1. Expeller giving groaning sound. 2. Violent vibrations in the machines. 3. Machines throwing the belts off. 4. Blowing the fuses of driving motor. |
1. Feed material is too dry. 2. Presences of metallic pieces in the cage. 3. Choking of cage and pressing worms. |
| Oil drips from discharge end. | 1. Improper fitting of worms and collars. |
Position of oil flow :
The heaviest flow of oil from the cage is normally at the feed section. If this does not happens and the oil flows from further along the cage at the center or discharge end, it is an indication that the expeller is not getting sufficient feed. In an expeller, the pressure is generated according to the volume of material fed to it. When the cage is not running full of meal, much pressure is lost, and the pressure is lost, good extraction will not take place and cake will contain more percentage of oil. The feed from the cooker should be regulated, so that the feed hopper is always full.
When the expeller is properly working, good amount of oil also flows through the intermediate chamber, but very little oil trickles out from the last chamber.
Abnormal discharge of Foots :
In expeller when properly prepared and cooked meal is pressed a small percentage of oily meal known as ‘foots’ is discharged along the cage. These foots are normally mixed with the meal in the kettle and thus disposed off in the process. If it is allowed to accumulate, they result in the development of acidity.
Sometimes there is an abnormal discharge of foots from the cage. It means that the pressure on the meal is being lost and the discharged cake will be containing more oil content. This may be due to improper cooking of the meal, or increased increased interspaces between the cage bars. Low fibrous material in the meal is also a frequent cause of an abnormal discharge of foots.
The cause of such abnormal discharge of foots, should be immediately removed, otherwise it will give heavy losses to the efficient working of the mill.
Expeller Refuses to Feed :
Position No. 1
If after running the expeller for sometimes in good order, and a good cake has been made, the expeller then refuses to take suffi-cient feed to give desire pressure and a good tough cake, the indications is that the oil is collecting in the press cage instead of quickly flowing out through the bars.
This generally occurs with more oily seeds and ir-regular feeding, when sudden rush of oil content cannot escape quickly. This oil mixes with the incoming meal, forms a spongy mass, which the worms cannot grip and is, therefore allowed to churn in the cage as an oily paste. If this happens the door of the feed chamber should be opened and oily mass is allowed to run out. The feed should be stopped and a few pieces of dry broken cake should be run, which will clear the whole cage. The feed from the cooker should then be opened and working resumed. If this defect becomes persistent, the chamber should be opened and the spaces between the cage bars of the feed section should be slightly enlarged by inserting suitable spacers between them.
Position No. 2 :
The expeller refuses to take meal, after it has been stopped for sometimes. This indicates that a block of hard-ened meal has been formed and is adhering to the worms and the cage lining. The generally happens when the meal is left in the cage before closing, which bakes hard in the heat of the press cage. When such an obstruction occurs, it is advisable not to attempt to force the meal, as it may result in damages. In such case, the chamber should be opened and the hard meal removed Such position should be avoided as far as possible by stopping the machines in a proper way as described in chapter-IV
Material Entering Pressure Cone :
Sometimes oil creeps in between the cone bore and the sleeves and retards the ready movement of the cone in or out. This oil becomes hard in between the cone and sleeves, due to presence of uncoagulated albuminoids in the oil which is released by improperly cooked meal. This happens because the cone remains hot due to friction and the albumen gets baked into an extremely hard thin cake, resembling a thin strip of ‘Bakelite’. It is this deposit which retards the free movements of the cone in or out.
To avoid such problems, the meal is properly cooked so that all albuminoids are coagulated and left in the cake. The cone should also be taken out at least once in 24 hours. When this is done, the sleeve on which it slides should be thickly greased, which will prevent albumen penetration too far.
Effect on Worms :
The pressing worms of an expeller usually get the heaviest wear & tear, which generally starts from the last worms i.e. worm which is nearer to the cone. If this worm is changed from time to time, the wear and tear on other worms is generally minimized. If worn out worms are allowed to continue, they create space between the bars and top rim of the worm, this prevents the material being forced forward and therefore keep churning in the feed section. This results low capacity and yield of the machine.
Sometimes oil drips continuously from the discharge end along the cake. This indicates that worms and collars are not properly fitted in the shaft and oil finds passage in between them and flows to the entire length of the shaft. This difficulty can be removed by putting thick brown paper rings in between the worms and collars etc.
