Inter-Ply Bond Strength Development in Recycled Fiber Formations under Variable Dewatering Pressures
Optimizing shoe press peak pressure and wet-end couch solids maximizes inter-ply bond strength in multi-ply recycled fiber formations.
Couching Solids
Moisture Retention
Water weight within the wet web of a forming paper sheet determines the density of couch solids. These couching solids define the mass fraction of fibre to total wet mass as the sheet leaves the couch roll on the wire. This measurement establishes the efficiency of water removal prior to the press section.
Mechanical Tension
Vacuum suction applied at the couch roll pulls air through the fibre mat to drive water into the suction box. High couching solids decrease the energy required in subsequent dryer cans. Increasing the suction pressure allows for higher dry content before the transfer.
Dense sheets sustain higher vacuum levels without crushing the web structure. Heavy basis weight papers demand lower speeds to reach the same consistency as lighter stocks.
Production Efficiency
Optimal couching solids dictate the load on the downstream vacuum pumps and thermal dryers. Low values force the paper machine to compensate through increased heat energy expenditure during the final drying phase. Consistency targets provide the benchmark for monitoring the performance of the wet end components over time.
Maintaining high levels prevents sheet breaks during the draw into the press nip. Consistent water removal ensures stable sheet strength throughout the continuous manufacturing cycle.