FORCES ON FIBERS IN LOW-CONSISTENCY REFINING

Forces on fiber flocs between passing bars have been measured in a ''s ingle-bar'' refiner. It was found that substantial force on fibers cou ld only be imposed over a relatively narrow range of gap size. The upp er limit of this size occurred when the floc was compressed to near it s zero void volume. The lower limit corresponded to a gap size in whic h flocs ruptured into two parts. The energy expenditure associated wit h these forces was found to compare favorably with energies per impact per fiber estimated in mill refiners using the C-factor.