Substrate Core Thermal Expansion Limits in High Speed Sheetfed Converting Operations
Substrate core thermal expansion limits dictate sheet dimensional stability, requiring precise thermal control to prevent misregister and bimetallic warp.
Non-Contact Optical Dilatometry
Precision Metrology
Measurement of dimensional changes in materials using light beams avoids any physical contact that could deform the sample. Utilizing non-contact optical dilatometry allows researchers to track the expansion and contraction of paper and board in response to temperature and humidity shifts. This technique provides highly accurate data without the risk of crushing or restricting the delicate fibres.
Optical Sensing
High-resolution cameras and lasers track the movement of specific markers on the surface of the specimen as it sits in a controlled chamber. As the moisture level or temperature is adjusted, the system measures the change in distance between the markers with sub-micron precision. This method captures the true, unrestrained movement of the material, providing a clear picture of its dimensional stability.
It is especially useful for analyzing co-extruded films and laminated boards where physical contact from traditional mechanical gauges would squeeze the layers and skew the measurement results.
Material Analysis
Data gathered from these tests is used to design paperboards with better dimensional stability for high-speed printing. Packaging designers rely on this information to select substrates that will not warp or curl when exposed to changing environmental conditions. This advanced testing helps mills optimize their fibre blending and drying processes to produce more stable paper products.