Property levels that are attainable in various board configurations at equivalent 

 board densities are given in table 14. Generally, strengths above 5,500 psi and stiff- 

 nesses (MOE) in excess of 750,000 psi are easily obtained for experimental panels having 

 alined flake configurations. One must provide cross-alinement or random orientation of 

 flakes in panels, however, to limit linear expansion. Three-layer random or homogeneous 

 flakeboards here have mean strengths in the range of 4,000 to 5,300 psi, and stiffnesses 

 (MOE) in the range of 600,000 psi to 800,000 psi. Linear expansion is controlled by 

 random orientation of the flakes. Internal bond levels for all panel configurations can 

 be sufficiently high to assure meeting requirements. These results show that structural 

 flakeboards can be prepared from sound wood residues that meet commercial standards and 

 Forest Service specifications. 



Furnish Requirements 



Furnish for structural flakeboard (especially surfaces) must consist of longer 

 flakes or stands than are normally found in particles in conventional particleboards . 

 Surface flakes should average 2 inches in length and 0.020 inch in thickness (Lehmann 

 1974; Saunders and others 1975; Snodgrass and Saunders 1974). Furnish for the core 

 should also consist mostly of long flakes to enhance linear stability. 



Flakes may be produced from fingerlings or directly from roundwood (fig. 12). The 

 flakes resulting from these two techniques differ in quality, but both may be employed 

 alone or in combination with each other to provide high performance structural flake- 

 boards. Disk flakes from fingerlings are of lower quality than disk flakes produced 

 from roundwood, but by alining f ingerl ing-derived ring flakes in the board, one may 

 attain high performance levels (Snodgrass and Saunders 1974) . 











BARKER 











FINGERLINGS 



Figure 12. — Two parallel processing procedures for forest residue conversion into 



structural flakeboard. 



19 



