Effects of A New Caul System on Strength and Stability of Structural Flakeboard
Pressing flakes or fibers at high moisture content (MC) may generate substantial benefits for the manufacture of wood composites. Such technology could reduce furnish drying costs and the risk of fire hazard, improve panel mechanicaland moisture soaking properties, and reduce emission of volatile organic compounds (VOCs) at drying of flakes and at hot pressing. However, high MC levels are restricted by the occurrence of blows and delamination in the conventional hot-pressing system. A perforated caul system may enlarge the area for the moisture to escape out of the board mat during pressing, and thus, making possible the high-moisture-content pressing. The objectives of this study were to evaluate the effects of planten hole number (PHN) and MC on the mechanical and dimensional properties of flakeboard. Three PHN levels (no holes, low PHN, high PHN) and 5 flake MC levels( 2%, 8%, 13%, 17%, 20%) were selected as the treatments. No blows or delaminations were found after 7-minute press cycles with flake MC up to 17 percent. This study showed that the perforated caul had the function of releasing moisture and vapor pressure during hot pressing.