Methods
The pelletizing components were measured
with dies and pistons produced for the purpose
(Fig 3) in an Instron 4485 testing machine with
a 200-kN load cell and a data logging system.
The Instron system was used to push the press
pistons and simultaneously measure the required
position and force. Electrical heating
(HSS braid coil, HT 30 regulator, Horst GmbH)
was used to adjust the temperature of the dies.
Data for Wcomp and Wfric were measured as illustrated
by Fig 3a – b. The press channel diameter
was 8 mm, and a pellet was made by compression
of 0.750 g sawdust to 15-kN maximum
force (300 MPa). Compression speed was 127
mm/min and the maximum force held for 10 s
(Fig 3a). After the pressure was released and the
stop piston removed, the pellet was pushed