The History Of The Flat Die Pellet Mill

Pellet machines have been in production for over a hundred years, and the first design was the flat die pellet mill. Today you will still see flat die pellet mills, however they are mainly produced in China. The reasons for this are that flat die pellet mills are much cheaper to produce and much simpler to manufacture. The reasons why almost all westernised pellet mill manufacturers have dropped the flat die in favour of the ring die pellet mill are performance, efficiency and parts wear. For instance here at PelHeat we only promote ring die pellet mills as seen in the video below.

The fist issue with the flat die pellet mill is called roller slip. This is caused because the rollers and die are rotating on different planes. The roller covers the whole surface of the die. The outer edge of the die rotates at a higher speed than the inner edge on a flat die pellet mill. Therefore as the roller covers the whole surface of the die there are forces trying the run the inner and outer edges of the die at different speeds. This is obviously impossible, and therefore the roller has to skip. This skipping action raises and lowers the height of the roller against the surface of the die. In production this gap should always be kept constant to keep pellet mill motor load constant. This is why on a flat die pellet mill you will see the amp meter shooting up and down. This also wastes a lot of energy. The ring die pellet mill which can been see on the mini pellet mill does not suffer from such issues and the amps remain constant throughout production. You can learn more about these differences in the pellet production guide, please click below.