The pellet mill
A pellet mill, used to create pellets from powdered material, is one of the most important machines in industrial production. The work of pressing the wet mash into a pellet is done through the die in the pellet mill. The mash enters the die by gravity from the conditioner or a small screw conveyor feeder is mounted on the door of the die chamber to force the wet mash into the die area. Once in the die area, the mash flows under a set of feeder rolls that press the mash into the die openings.
The spacing between these rolls and the inner surface of the die is critical and must be adjusted to the correct measurement “gap” to force the mixture from the roll through the die without the mix slipping and not entering the die correctly.
This is called rollers slippage and it causes the blockage of the machine.
If enough mash material enters the rolls area but isn’t forced into the working track, the pellet mill will plug and has to be stopped and cleaned out before continuing production.
If many different formulas are pelleted, it may be critical to adjust the feeder roll gap to force the mixture into the die holes for different ingredients.
Most pellet mills have manually adjusted rolls settings that must be done when the pellet mill is stopped and the door to the pelleting chamber is opened to access the adjustment point.
The hydraulic roller adjustment enables:
easy finding the right roller gap with just the touch of a button
the operator to adjust the roller gap, even when the pellet mill is in operation
By using the right roller gap, the die and roller lifetime can be increased.
Most pellet mills now have one or more conditioning units mounted above them.
Conditioning is accomplished by the addition of controlled amounts of steam, that supplies moisture for lubrication, liberates natural oils and results in partial gelatinization of starches.
The pellet mill and motor are usually mounted on a common base to maintain alignment of the pellet mill and motor and to provide a rapid, simple and efficient method of installing the equipment.