Structural Flakeboards and Composites 



INITIAL TEST 



10 



«0 



9 - 



2923 

 ACCELERATED AGING 



• 52.6 pcf TARGET DENSITY 

 I I 



I.I 



1.2 



1.4 I. 



1.2 



1.3 



1.4 



COMPACTION RATIO 



Figure 24-5. — Modulus of elasticity related to compaction ratio of 1/2-inch-thick south- 

 ern red oak and mockernut hickory panels made from 2-1/4-inch-long, 0.020-inch- 

 thick flakes cut on four types of flakers. Panels fabricated at the target density of 52.6 

 Ib/cu ft are accentuated. (Left) After accelerated aging. (Drawing after Price and 

 Lehmann 1978.) 



to 90 percent, was least with shaping-lathe-cut flakes (figs. 24-8 top and 24-9). 



At high compaction ratios, sweetgum panels had highest bending strength 

 and stiffness when made from disk-cut flakes (figs. 24-10 and 24-11), but 

 highest internal bond strength when made from ring-cut flakes. Sweetgum 

 boards were most stable when fabricated from shaping-lathe-cut flakes (fig. 24- 

 12). 



Flake splitters. — Some of the southern hardwoods (e.g., sweetgum) yield 

 very wide flakes that may fold and inhibit resin application; others (e.g., hick- 

 ory) tend to form tubular flakes on which it is difficult to uniformly apply resin. 

 In the laboratory, an ordinary household leaf shredder does a good job of 

 reducing the width of such flakes. Several industrial machines are available for 

 this purpose; e.g., see Sybertz and Sander (1975). 



