“The occurrence of a breakdown in a feed plant may cause the production to stop for an unpredictable period of time. In order to avoid such a situation, mechanical maintenance of the machinery in the plant must be carried out at certain intervals.”
Mechanical Engineer-Technical Department Assistant Director
Yemmak Makina Sanayi ve Ticaret A.Ş.
Periodical inspection and mechanical maintenance of machines and equipment used in feed production processes are crucial for preventing possible breakdowns. A non-foreseeable failure may stop the production for an unpredictable period of time. From raw material intake to packaging, all machines have parts and units that need to be replaced due to abrasion and fatigue. The maintenance of all machinery and their parts directly affects the capacity and the feed quality of the facility. The main machinery of feed facilities and their parts that need to be taken care of are:
Pellet mill is one of the most important machine of a plant that produces pellet feed. In the pellet mill, which directly affects the feed production capacity and quality, the maintenances to be done in particular are given below.
Die and rollers: Die and rollers are the parts that pelletize the mash feed. During feed production, these parts wear out over time. The abrasion of inlet tapers in the die, and abrasion of the channels and counterbores on the roller reduces the capacity of the pellet mill. These parts which have to be checked regularly and grinding applied if necessary, and new channels and counterbores have to be reopened. If the wear is beyond a level that allows a reopening of the die and rollers must be replaced with new ones.
Bearings: The main bearings must be lubricated every 100-200 hours. The lubrication operation of the roller bearings should be between 10-220 grams per hour depending on the size of the pellet mill. The roller bearings of the most commonly used ø660 and ø900 pellet mills are lubricated as 100 gr / h and 220 gr / h.
The transmission in the drive system has to be checked periodically. The performance of belts in a belt-pulley driven pellet mill directly affects the performance therefore, the tension of the belts should be kept under control. The cracks on the belts should be checked consistently and the belts should be replaced if necessary.
A hammer mill is a machine that can break down grains and other grained raw materials to desired sizes.
Hammers: Hammers are one of the most important parts that wear out and affect the performance of the machine. In order to prevent this abrasion, the hammer mill is run in the clockwise direction one day and in the counter-clockwise direction the following day. By this mode of operation, two corners are equally eroded. In the same manner, the hammers are taken out and reversed in following days. As a result of this reversal, every four corner of each hammer are used equally.
Screen sheets: After a certain working time, the holes on the screen sheet will widen and exceed the desired magnitude. And this affects the milling performance negatively and reduces the quality of the feed. Therefore, the screens should be replaced after a certain operating time.
Bearings: Bearings must be lubricated once for every 1300 hours operation period. Besides, their temperature should be checked regularly. The temperatures above 50-60 ° C are a precursor for the lubrication time or the time for replacement of bearings.
Coupling: The barrel-shaped rubbers of the couplings with a pin must be checked for a deformation and replaced if necessary.
A paddle mixer is a machine that is used for mixing mineral and premix products with dosed and crushed grains homogeneously.
Bearings: The bearings of the paddle mixer must be lubricated once in 500 hours periods.
Drive unit: The oil of the gear box must be checked regularly and changed if necessary. In the same way, the situation of the belts in the unit must be checked and replaced in case of a deformation.
The leak-tightness of the mixer’s bottom lid is a very important subject. The seals around the doors must be checked and if they are worn out they must be replaced with new ones.
The molasses is one of the essentials in cattle feed production. The mixture getting out from the paddle mixer is coated with molasses at the entrance of the molasses mixer. Then, molasses is homogeneously mixed with the mash mixture thanks to the pallets on the molasses mixer rotor.
Cleaning: Molasses is sticky and hardens when gets dry. For this reason, the inner surface of the molasses mixer should be cleaned at least once a day. Otherwise, the pallets will be worn out in a short time.
Bearings: Bearings of the molasses mixer must be lubricated once in 1000 hours.
Pallets: Pallets wear out due to operating conditions. For this reason, the distance between the pallets and the body should be checked and in case they are eroded they have to be replaced with new ones.
Drive unit: The tension of the belts must be checked. The cracks on the belts should be checked and the belts should be replaced if necessary.
The control and mechanical maintenance of the bucket elevators which are used for vertically lifting of the product are carried out with the help of following parts.
Bearing Units: Bearings must be lubricated once in 6000-7000 hours periods.
Gear Box: The gear box must be checked for oil and changed regularly.
Coupling: The coupling rubbers have to be checked and replaced in case of abrasion.
Bucket and Belt: Buckets and belts of the elevator wear out as they operate. Depending on the abrasiveness of the conveyed product, the buckets, bucket bolts and belt should be replaced at the end of a certain period of time.
In the chain conveyors, which are used for conveying the product horizontally, check and mechanical maintenance are carried out in the following parts.
Roller Bearings: Roller bearings must be lubricated once in 10000-12000 hours periods.
Gear Box: The gear box must be checked for oil and changed regularly.
Coupling: The coupling rubbers must be checked and replaced if necessary.
Pallet and Chain: Commonly used plastic based pallets must be changed at the end of a certain working hour depending on the abrasiveness of the product being conveyed.
A sewing machine is a machine used to sew the mouth of the bag. The cleanliness and oil status directly affect the operation of the machine. Cleaning should be done at the end of each shift. The gear oil must be checked and replaced when decreases.
A steam boiler is used to condition mash feed during feed production and to get rid of harmful bacteria. Periodic examinations of steam boilers should be carried out by accredited organizations. In these examinations, vital controls such as pressure relief valves, low-water level alarms and leaks have to be performed. Periodically, boiler water should be analyzed and, if necessary, some chemicals should be added to prevent possible damages to the boiler. These chemicals serve to reduce the hardness of water and reduce the oxidation.
Maximum values desired for the boiler feed water has to be as follows:
Total Hardness: less than 1-2 FSB
Oil Content: less than 2 mg / lt
Oxygen: less than 0.005 mg / lt
Total Iron: less than 0.005 mg / lt
Total Carbon Dioxide: less than 20 mg / lt
Silicate (SiO2): as low as possible
Plt Value: between 7 and 9.5
Mechanical maintenance of the machinery in the feed mills should be carried out periodically to ensure that they do not break down unexpectedly and cause a halt in production. Wearable parts of the machine, as well as materials such as electric motor, gear box, bearing, level sensor and temperature sensor must be kept as spare and it should be aimed at repairing a possible breakage in short period time.
We also suggest you to read our previous article titled "Material Handling and Maintenance in Feed Milling".