A schematic diagram of the manufacture of LVL is shown in Figure 2 below.
The initial steps of manufacture of LVL are similar to those used in the manufacture of plywood. Typically, logs are rotary peeled on a lathe to create veneer sheets from 2.5mm (1/10″) up to 4.8mm (3/16″) in thickness. Veneer sheets are generally about 2640mm (104″) long by either 1320mm (52″) or 660mm (26″) wide.
The veneer sheets are dried, clipped to remove major strength reducing defects, and graded. The sheets are cut to the required width for the billet to be produced.
Figure 2: Manufacture of LVL
The individual veneers are then assembled with the grain of all veneers running in the long direction of the billet. End joints between individual pieces of veneer are staggered along the length of the billet to disperse any remaining strength reducing defects. The joints may be scarf jointed or overlapped for some distance to provide load transfer.
The veneer lengths are coated with a waterproof phenol-formaldehyde resin adhesive. The assembled billets are subjected simultaneously to pressure to consolidate the veneers, and to heat to accelerate curing of the adhesive. Once again, this aspect of the process is similar to that for plywood except that rather than being in a thin flat panel shape, the LVL material is formed into long billets up to 25m (80′) in length.
Once cured, the billets are sawn to custom lengths and widths as desired for the product end use.