Silent Paper Grade Furnish Substitution Mechanics at Machine Gate
Furnish substitutions at the machine gate require wet end NIR tracking and ISO 1924 tensile verification to prevent runnability failures and yield losses
ISO 1974
Tear Measurement
Standardized Elmendorf testing determines the internal tearing resistance of paper and paperboard sheets under defined mechanical conditions. Quality control laboratories execute ISO 1974 to measure the energy required to propagate an initial cut through a stack of paper test specimens. The standard applies to low and medium grammage paper products measured in both machine and cross directions.
The scope excludes corrugated board and high-grammage solid fiberboards exceeding the mechanical measuring range of standard pendulum instruments.
Pendulum Action
Specimen preparation requires cutting rectangular samples to exact dimensions and creating an initial notch using an integrated precision blade. A weighted pendulum releases from a fixed raised position, tearing the notched specimen stack as it swings through its arc. Potential energy lost by the pendulum during tearing converts directly to a force reading expressed in millinewtons.
Testing multiple sheet plies simultaneously averages out local formation variations across individual samples. Applying ISO 1974 provides quantitative data essential for verifying substrate suitability in heavy-duty packaging and web-fed printing operations.
Mechanical Endurance
Substrate tearing resistance dictates runnability during high-tension rotary printing and automated packaging operations. Fiber length and internal fiber bonding directly influence tearing force values across paper machine runs. Weak tear strength causes web tearing and machine downtime on converting lines.