Non-Contact Caliper Measurement Systems on High Speed Packaging Board Lines
Non-contact optical gauges eliminate mechanical board compression on high-speed lines, enabling tighter cross-machine caliper targets and reduced fiber mass.
Viscoelastic Compression
Substrate Deformation
Mechanical energy absorption defines the response of porous fibre networks subjected to rapid load application. Viscoelastic compression represents the dual behaviour of a material as it simultaneously stores elastic energy and dissipates work through internal friction. Manufacturers evaluate this property during the initial stage of converting where high speed rollers reduce the thickness of paperboard sheets.
The measurement quantifies how much a substrate recovers its original profile after the removal of a momentary stress pulse.
Recovery Analysis
Proper characterization of viscoelastic compression relies on the time dependent relationship between applied pressure and the rate of structural consolidation. A sample under test reveals different results when the frequency of the mechanical pulse shifts from low to high. Rapid loading cycles force air out of the microscopic void spaces between cellulose fibres while the polymer matrix resists immediate lateral flow.
Permanent gauge loss occurs if the pulse speed exceeds the threshold where the network internal bonds hold their relative positions against the deformation force. Accurate data requires the isolation of moisture content effects because water acts as a plasticizer and alters the internal damping capacity of the sheet.
Production Variance
Calendering operations demand strict control over the viscoelastic compression of incoming stock to maintain uniform thickness across a web width. Constant pressure profiles at the nip point create predictable surface finishes but only if the sheet exhibits consistent relaxation kinetics. Variations in the fibre refining process shift the equilibrium between elastic spring back and plastic collapse during the contact phase.
Heavy weight boards require higher energy inputs to achieve specific density targets without triggering irreversible fibre crushing. This metric determines the operational window for heavy duty embossing or creasing tools in secondary packaging lines.