Short answer: a type R (roller rotation) pellet mill is a flat die machine in which the rollers turn and the die stays fixed. It applies more pressure and "grips" dry, light or slippery materials that do not feed well into a standard pellet mill: very dry wood, long shavings, husks, bagasse. In exchange, it produces 40% to 50% of what a standard machine of the same diameter does, and costs more. If your material pelletizes well on a standard machine, the standard one is the better buy. Below, how to tell which one you need.
What changes between type R and standard
In a standard flat die pellet mill (Meelko's C series), the motor turns the die and the rollers turn as the material drags them. With animal feed, alfalfa or ordinary sawdust, it works very well: it is fast and produces a lot per kW.
The problem appears with materials that have no natural cohesion or are very dry: the material slips, the rollers skid and cannot force it into the die holes. In type R, power goes straight to the rollers, which run slower but with more torque over the fixed die. The result:
- More compaction pressure and denser pellets.
- Better grip on materials that slip in a standard machine.
- Fewer fines and less breakage in the finished pellet.
- Lower hourly output, because of the slower speed.
Which materials call for type R
- Wood: very dry pine, eucalyptus, quebracho, poplar.
- Coarse sawdust and long shavings, or sawdust with irregular particle size.
- Plant biomass: peanut hulls, sunflower husks, crushed cane, dry bagasse.
- Dry joinery offcuts, free of glue and paint.
- In general, any fibrous, very dry or low-cohesion mix.
For animal feed, alfalfa, pasture, fertilizer or ordinary sawdust, the standard machine is the right choice: it produces twice as much and costs less.
The models, with their standard counterparts
Type R pellet mill capacities as stated on each product page, varying with the material:
- MKFD120R: 6 to 15 kg/h. USD 3,950. Its standard counterpart, the MKFD120B, costs USD 2,024.
- MKFD200R: 25 to 65 kg/h, 7.5 to 11 kW. USD 5,550. Standard: MKFD200C, USD 3,142.
- MKFD300R: 60 to 140 kg/h, 18 to 22 kW. USD 12,300. Standard: MKFD300C, USD 7,901.
- MKFD360R: 70 to 180 kg/h. USD 14,900. Standard: MKFD360C, USD 9,393.
For the MKFD360R, for example, the product page states 120 to 180 kg/h with mixed biomass and 90 to 140 kg/h with hardwood.
How to decide
- Does your material pelletize on a standard machine? If it is feed, alfalfa or ordinary sawdust, yes: choose standard. For C series sizes and outputs, see pellet mills from 120 to 400 mm.
- Is it hardwood, very dry, shavings or husks? You probably need type R, or a ring die pellet mill if the volume is large.
- How much do you need to produce? Since type R produces less, run your own numbers. For 100 kg/h of peanut hulls, the MKFD360R is enough; for 500 kg/h of hardwood, no flat die is the answer: that calls for an industrial ring die pellet mill.
A common mistake
Buying a standard machine for hardwood or husks because it is cheaper, then finding that the material slips, the machine clogs and real output falls far below the spec sheet. In that case, the price difference with type R is lost within a few months of low production. The reverse also happens: buying type R for animal feed means paying more to produce half as much.
If you are setting up a wood pellet plant, see also sawdust pellet plant.
Conclusion
Type R is neither better nor worse than standard: it is the tool for difficult materials. If your biomass is dry, fibrous or slippery, it is the one that will make quality pellets; if not, the standard machine gives more output per dollar. Meelko, an American brand of agro-industrial machinery, offers both lines from 120 to 360 mm. Tell us what material you have, its moisture and how many kilos per hour you need, and we will tell you which one fits.
