Standard Laboratory Methods for Paperboard Flexural Rigidity
Paperboard flexural rigidity depends on the cube of caliper, requiring exact ISO 2493 or TAPPI T 489 instrument alignment and strict 23°C/50% RH conditioning.
Load Cell Calibration
Measurement Accuracy
Metrological verification ensures that force transducers produce electrical outputs that correspond precisely to known mechanical loads. For testing laboratories and processing machinery, regular load cell calibration establishes the traceability of force measurements to international standards. This process involves applying certified reference weights to the transducer and recording the resulting electrical signals across the operating range.
The resulting calibration curve compensates for non-linearity, hysteresis, and zero-drift errors that accumulate over time. Maintaining this accuracy prevents false readings during material testing and ensures that the physical properties of the paperboard are reported correctly. By verifying the instrument across its full measurement span, the calibration provides the statistical confidence needed to certify that the manufactured materials comply with the tensile specifications of the buyer.
Tension Control
Web tension regulation prevents tearing and wrinkles in high-speed winders and printing presses. In roll-to-roll converting, accurate load cell calibration prevents the web from stretching or breaking as it travels through the coating and calendering stations. When the load cells are misaligned or drift from their calibrated state, the tension feedback loop fails, which causes uneven winding or edge curling.
Correctly calibrated sensors ensure a uniform tension profile throughout the roll.
Tensile Testing
Material specification compliance depends on the precision of laboratory bench tests. When evaluating the tensile energy absorption of paperboard, the load cell calibration of the tensile tester must be maintained within tight tolerances. A deviation in the force sensor can cause a batch of compliant board to be rejected or lead to the shipment of substandard stock.
Regular checks with precision weights are required to keep the instrument within certified limits.