Table 17. --Mean strength properties for flakeboards of disk and ring flakes from forest residues containing decay. 



Species 



Flake 1 

 type 



Initial condition 



After accelerated aging 



Modulus Modulus 



of of 

 rupture 3 elasticity 3 



Internal 

 bond 



Modulus Modulus 

 Specific of of Internal 

 gravity 2 rupture 3 elasticity 3 bond 



Based on thickness prior 

 to accelerated aging 



lh/in 2 



Aspen Disk 0.592 4,465 670 35 2,639 594 3 



Ring" .576 2,682 443 35 1,834 368 3 



Paper Birch 



Disk 



.589 



2 , 156 



426 



38 



1 ,332 



243 



3 



Ring 1 * 



.593 



1,828 



332 



22 



,1 ,204 



240 



2 



Western Larch 



Disk 



. 585 



2,375 



335 



45 



1 ,332 



192 



14 





Ring 1 * 



.577 



2,772 



408 



31 



1 ,859 



293 



9 



Douglas-fir 



Disk 



.608 



4,119 



543 



74 



2,880 



438 



25 



Ring" 



.622 



2,894 



450 



56 



1 ,888 



349 



13 



Douglas-fir 



Disk 



.595 



2,744 



503 



53 



1 ,776 



342 



21 





Ring 5 



.596 



2,370 



426 



50 



1 ,486 



258 



25 



Douglas-fir (58%) 



Disk 



.595 



3,339 



4_87 



46 



2,992 



505 



28 



Western hemlock 



(42%) Ring 5 



.602 



2,883 



410 



54 



2 ,357 



359 



30 



Lodgepole pine 



















Dead 



Disk 



.578 



4,034 



594 



32 



2,908 



485 



19 





Ring 1 * 



.587 



3,096 



469 



59 



2,228 



373 



22 



Green 



Disk 



.564 



3,650 



522 



53 



3,079 



488 



24 





Ring" 



.590 



3,173 



1 S h 



73 



2,635 



463 



10 



Disk flakes: Logs reduced to 2-in-thick disks--disks were reduced to flakes on a disk f laker. 



2 Specific gravity based on ovendry weight and volume at 65% relative humidity. 



3 Corrected to a common mean specific gravity. 



"Ring flakes: Logs reduced to fingerlings on "spiral chipper." Fingerlings reduced to flakes on a ring flaker 

 5 Ring flakes: Logs reduced to fingerlings on "drum chipper." Fingerlings reduced to flakes on a ring flaker. 



SUMMARY 



Residue harvesting for structural flakeboard furnish should be increasingly 

 economically attractive as markets in the Rocky Mountain area develop, structural 

 flakeboard prices increase, and residue harvesting costs fall. Theoretically, a 

 fingerling chipper working with one of five proposed harvesting systems could 

 deliver fingerlings to the flakeboard mill for $25 to $33 per bone-dry ton for 

 systems other than cable yarders . 



The conversion of residue to fingerlings at the logging site for simplified 

 handling and hauling appears to be attractive technically and economically. A modified 

 drum chipper and a spiral chipper can produce fingerlings in the woods or at the mill 

 that can be further converted to ring flakes for alined-f lake, or random-flake struct- 

 ural flakeboard that meets or exceeds commercial standards or Forest Service standards. 

 Experimental alined-flake flakeboard made from f ingerling-derived flakes achieved mean 

 strengths above 5,500 psi and stiffnesses (MOE) above 750,000 psi. Mean strengths 

 of random-flake panels were above 4,000 psi and stiffnesses (MOE) above 600,000 psi. 

 Because f ingerling-derived ring flakes are inferior to disk flakes, high-strength 

 structural flakeboards should employ disk flakes, or else the longest ring flakes 

 should be positioned in the board surface. 



A modified drum chipper with a 200 hp engine was estimated to produce 3/8-inch- 



thick fingerlings from large diameter residue at a rate of 50 tons per hour. Smaller 



residue (1-9 in) can be reduced to fingerlings in a spiral chipper at an estimated 

 rate of 15 tons per hour (60 percent feed rate) . 



22 



