Flat die pellet machines have a perforated disk or plate, and rollers press the material through the disk holes. The vertical design of these industrial pelleting mills makes the process simpler and their cleaning more convenient.

Flat die machines fall into two groups: die-driven and roller-driven. Die-driven flat die pelletizers have stationary rollers and a rotating die, whereas, in the roller-driven type, the die is still, and the rollers rotate. The latter configuration exerts more compression power on the raw materials, so it is a better option for pelleting hard materials such as sawdust hardwoods. Meanwhile, it creates less stress on the die, prolonging its life.

Flat die presses are typically used to make biomass pellets from wood, manure, straw, alfalfa, or fodder. However, this technology is also suitable for small-scale animal feed production.

An industrial feed pelleting line involves a hammer mill, mixer, pre-conditioner, pellet mill, and cooler. Pellet presses are used to produce compound feed and feed concentrates, as well as specialized feed for poultry, swine, cattle, and other farm animals. Sinking pellets may also be made using a pelleting machine, but aquafeed products are typically produced with an extrusion line.

For farm production or small-scale production, there is a more basic pellet manufacturing process involving a flat die pellet. It is a vertical process, where the mixed ingredients are fed through a hopper on the top and descend into a turning roller that presses them against the die.