Making pellets is process which can be dramatically different depending on the material you are processing and the end use for the product. For instance here I’m going to talk about the need for sufficient temperature in the pellet press to produce high quality fuel pellets, however too much heat in the pellet press for feed materials and it can damage the product.
As you may know for biomass materials to form a pellet of sufficient density and durability lignin is required. Lignin is the starch that gives the plant its strength, therefore as you can imagine wood has more lignin than say straw. Some materials do not contain enough lignin, and therefore an additional binder is added to aid the process such as modified corn starch. However with other materials if the right temperature and pressure can be achieved in the pellet press the natural lignin from within the material can be used as a binder.
In the pellet press temperature and pressure have a close relation ship. While you want to achieve a temperature high enough to melt the lignin to bind the pellets you will also be increasing the pressure within the pellet press die at the same time. However if the pressure gets too high the rollers will not provide enough force to push material through the die and this will lead to a blockage. This is typically the case if die has not been drilled to a high standard or there is a build up corrosion on the interior surface of the die holes which has not been removed.
We drill each die to suit the material being processed to create the right amount of temperature and pressure within the pellet press die. If the pressure does appear to be getting too high small amounts of vegetable oil can be dripped into the process.