Optimizing Chemi-Thermomechanical Pulp Core Fractions for Lightweight Board
Balancing middle ply mechanical pulp freeness preserves sheet caliper and bending resistance while controlling delamination under high-speed scoring.
High Consistency Refining
Fiber Modification
Mechanical treatment inside disk apparatus alters secondary cell wall architecture before paper machine wet ends. High consistency refining forces unbleached chemical pulp between rotating metallic bars at 25 to 35 percent dryness. Mechanical shear induces internal delamination and external fibrillation without excessive length reduction.
Retained fiber length maintains tear resistance while increased specific surface area improves tensile strength development. Structural changes elevate bulk properties within packaging grades requiring high stiffness from lower grammage substrates.
Energy Transfer
Thermal and mechanical power consumption dictates operational efficiency during high consistency refining. Specific energy inputs range from 150 to 300 kilowatt hours per ton depending on target tear and tensile ratios. Plate geometry design directly influences fiber residence time and load distribution across active bar edges.
Motor torque fluctuations demand precise axial positioning to prevent stock plugging or plate clashing within the housing. Water removal rates downstream depend on hydrodynamic permeability established during this mechanical processing stage.
Operator Control
Process automation maintains targeted fkaness levels despite incoming raw material variations across multi-stage mill lines. Closed loop control systems adjust plate gap clearance based on real time power load feedback and flow rate sensors. Refining intensity parameters govern bonding potential within corrugated medium and linerboard webs produced from recycled or virgin furnishes.
Dimensional stability improves when optimized treatment limits curl and twist defects in converted folding boxboard. Mechanical working determines final converting performance by balancing folding endurance against bursting strength requirements.