Clipping veneer

Bark, sawdust, veneer clippings and wastes, panel trim, sander dust... 

The veneer dryers of a plywood mill are large chambers equipped with heating elements and fans utilizing automatic conveying systems on which the veneers are transported. Some dryers are located behind the rotary lathe, which allows the cut veneer to be dried in a continuous sheet or ribbon and then clipped dry afterwards. 

Parallel strand lumber is manufactured from veneer about 3 mm (1/8 in.) thick, that is clipped into strands about 19 mm (3/4 in.) wide and 0.6 m (24 in.) long. The produet was designed to use waste material from the roundup lathe as well as other less than full-width veneer arising from plywood manufacture (Chapter 11). Species eommonly used for PSL include Douglas fir, southern pines, western hemlock and yellow poplar, but there is no restriction on the use of other species. 

Plywood production can typically be divided into three manufacturing stages (Figure 11.2) veneer manufacture clipping, drying and up-grading and panel layup,... 

There are alternative mill configurations. Some modem mills direct the veneer from the lathe to the dryer and only then to the clipper. The advantage of clipping after drying is that veneer can be cut to size much more accurately than when green. The yield can be increased by some 3-5%. 

Computerized clippers use scanners to detect breaks and defects in the veneer and then automatically clip these out. Typically 15-35% of veneer is in narrow strips and a clipper might spend 40% of its time trimming round-up and 60% of its time... 

---