Internal temperature and pressure responses to flake alignment during hot-pressing

This paper investigates the effects of different flake alignments and densi ties on the heat and gas flow within an oriented strandboard mat during hot -pressing. Robot-formed single layer flake mats, with alignments of 100% (p erfectly aligned), 80% (partially aligned) and 0% (completely random), and average densities of 614 kg/m(3) and 446 kg/m(3), were pressed at 180 degre esC to a 10 mm thickness. Steel capillary tubes and thermocouple wires were inserted during mat forming at various thickness positions to monitor gas pressure and temperature. Panel density was found to positively affect ther mal conduction, and negatively affect lateral and transverse permeability a nd transverse thermal convection. Flake-alignment positively affected later al permeability, and negatively affected transverse thermal convection. The se results indicate that lower density mats will heat faster and have lower internal gas pressures. Less aligned mats will initially heat faster and h ave higher internal gas pressures, but towards the end of pressing they wil l take slightly longer to heat.