Fiberboards 



2821 



Table 23-7. — Estimated manufacturing costs for two thicknesses of wet- and dry-proc- 

 ess hardboard^ (FAO 1976; Vajda 1976) 



Wet process 



Dry process 



Item 



3.2-mm 

 board-^ 



1 1-mm 

 siding^ 



3.2-mm 

 board'^ 



11-mm 

 siding^ 



Manufacturing costs 



Wood at $25/ovendry ton 29.40 



Resin 2.10 



Wax 3.30 



Alum 1.17 



Power 5.75 



Fuel 8.08 



Labor 18.46 



Operating and maintenance supplies . 11.73 



Administration and overhead 7.04 



Taxes and insurance 5.46 



Cutting , priming , and packaging costs — 



Total manufacturing cost excluding 



interest and depreciation 92.49 



Depreciation (15-year straight line). ... 28.72 



Total cost 121.21 



'Based on 325 operating days annually. 

 ^65,000 tons annual production. 

 ^72,000 tons annual production. 

 "^60,000 tons annual production. 

 ^90,000 tons annual production. 



Efforts to produce dry-formed fiberboard without addition of resin binder 

 have generally been unsuccessful. Only one binderless dry fiberboard process 

 exists. The plant, which is in Czechoslovakia, uses defibrator pulp further 

 processed in atmospheric Bauer refiners. The boards are pressed with sealing 

 frames to control release of water and gas, which appears to be critical to the 

 process (Swiderski 1963; Nagy 1964; Pecina 1980). 



In addition to conventional platen-pressed thick and thin, medium- and high- 

 density dry-process fiberboards, a unique continuous board process, the Mende 

 process, applicable to the manufacture of both particleboard and fiberboard was 

 developed in Germany and is being used to some extent in the United States. 

 Since board thickness is limited to about 1/4-inch, it competes directly with 

 conventional dry- and wet-process hardboard. One of the attractive features of 

 the Mende process is its capability to produce hardboard on a small scale 

 economically, as described later. Alignment of fibers in the fiber mat to enhance 

 certain board properties in one of the principal directions of the board is a fairly 

 recent development, and will be discussed briefly at the end of this section. 



