Pilot plant evaluation of steam-injection pressing for LVL and plywood products

Using steam-injection technology in pilot plant trials, substantial reducti ons in pressing time were achieved both for 7-ply (spruce, pine, subalpine fir (SPF)) plywood and 13-ply SPF laminated veneer lumber(LVL). Specificall y, a steam-injection time of 1 minute using saturated steam at 80 psi reduc ed the pressing time of 7-ply SPF plywood by 27 percent compared to convent ional platen pressing. A steam-injection time of 8 minutes using saturated steam at 80 psi reduced the pressing time of 13-ply SPF LVL by 32 percent c ompared to conventional platen pressing. Both the control and steam-injecte d 7-ply SPF plywood and 13-ply SPF LVL panels exhibited excellent bond qual ity and the average percentage wood failure was much greater than 80 percen t in all cases, thereby meeting the average percentage wood failure require ment in the CSA 0151 plywood standard. There was no significant difference in shear strength between control and steam-injected shear specimens. There was no statistical difference in average modulus of elasticity or modulus of rupture under flatwise and edgewise bending for the steam-injected LVL c ompared to the control LVI, made using conventional platen pressing. The sh orter pressing times using steam injection technology would enable LVL and plywood plants to increase their production and substantially increase thei r profit.