Material Optimization
Reduction of the calliper or basis weight of a packaging grade without compromising its performance during storage and transport is a primary objective in sustainable packaging design. Implementing board downgauging allows manufacturers to use less raw fibre while maintaining the required stiffness for structural integrity. This strategy relies on advanced multi-ply structuring, where high-yield pulp is concentrated in the middle layer to maximize the moment of inertia.
Mechanical Formulation
Bending stiffness depends heavily on both the thickness of the board and the elastic modulus of the outer plies. Through board downgauging, producers can reduce overall material usage by utilizing chemical additives or microfibrillated cellulose to boost the strength of thin plies. This process must be carefully controlled because a thinner sheet can exhibit decreased resistance to compression, potentially leading to box failure under top-to-bottom compression loads.
Refining strategies and starch applications are adjusted to ensure the outer surfaces retain high tensile stiffness.
Process Impact
Runnability on converting lines is directly affected by changes in sheet thickness and weight. Cartonboards treated with board downgauging can experience different heat transfer rates during sealing and creasing. Modifying the creasing matrix helps prevent rupture of the thin outer plies during carton formation.
