Abstract: A pellet mill includes a die carrying material to be extruded into pellets. The die rotates to bring the material toward rollers within the die. The rollers push the material through extrusion holes in the die. The rollers are mounted on and rotate about support shafts that are held stationary within the die. Sealing devices at the ends of the rollers prevent foreign material from interfering with bearings between the rollers and the support shafts. Each of the sealing devices include one or more sealing elements. The sealing elements may include a pair of mating grooves and protrusions.

Abstract: A pelleting die is made of martensitic stainless steel and includes a plurality of extrusion holes form through the die. The surfaces of the die, including surfaces inside the extrusion holes, are hardened by gas nitriding or plasma nitriding. A martensitic stainless steel die can have a carbon content of at least 0.4%. A martensitic steel die can be made of SAE grade 420 steel which is plasma nitrided to produce hardened surfaces. Plasma nitriding can be performed at sufficiently a low temperature to avoid softening of the 420 steel core.

Abstract: A pelleting die is provided, preferably in cylindrical form. The die includes a cylindrical body having inner and outer cylindrical surfaces and holes through the surfaces in which particulate material is extruded to form pellets. The die is formed of an H-group steel alloy, preferably H13 alloy, with the surfaces being nitrided to provide increased surface hardness, resistance to wear, improved fatigue life and improved corrosion resistance.