Recycled Boxboard Fiber Classification and Mechanical Refining Dynamics
Fractionating recycled furnish prior to low-consistency refining preserves boxboard caliper while meeting internal bond targets at reduced energy consumption.
Disc Refiner Bar Profile
Plate Geometry
Structural patterns on the metal plates of stock preparation refiners determine the mechanical properties of developed pulp. The specific arrangement of ridges and grooves, known as disc refiner bar profile, controls the intensity of fibre shortening versus fibrillation during refining. This pattern dictates how wood fibres are held and sheared as they pass between the rotating and stationary plates.
Fibre Development
Mechanical action on the pulp slurry depends on the width, depth and angle of the machined bars. A narrow disc refiner bar profile promotes fibrillation, which increases the bonding potential of softwood fibres without cutting them too short. This action develops the tensile strength and tear resistance of the paper sheet needed for demanding packaging applications.
Refining Efficiency
Optimizing this pattern reduces the energy needed to reach the target pulp freeness during stock preparation. Mill operators select the bar profile based on the botanical origin of the wood pulp and the desired stretch properties of the paper. This selection of disc refiner bar profile minimizes fibre damage while maximizing the burst strength of the final testliner or fluting grade.
Proper geometry also extends the service life of the refiner plates by distributing mechanical wear evenly across the plate face.