Chip Yield and Materials Balance as Related to Log Size in the California Pine and Fir Region

During the early planning stage for a new mill it was necessary to obtain reliable data on the quantity of wood chips that would be available. The size and capacity of the sawmill was fixed by the sustained yield of the company’s timberlands but the economic size and capacity of the molded pulp operations were determined by the quantity of bark-free chips that would be produced by the lumber manufacturing end. An engineering approach is presented for dealing with this matter as a volumetric materials balance, with total volume (cu. ft.) of solid wood in the various products equalling the incoming log volume (cu. ft.). It was assumed that: in-coming logs are similar to the pine and mixed conifer timber types located in the Sierra Nevada mountains of northern California; average log grade and percentage of log defect have an important effect on the volume of green chippable obtained and the sampling should represent the average log grade of the timberlands; all logs entering the mill are whole-log barked to obtain clean chips; logs of 10-inch diameter and smaller are slabbed on two sides and sawn alive, all logs larger than 10-inches in diameter are sawn to obtain maximum recovery; logs are sawn on bandmills; the end product is primarily 4/4 selects and common, 6/4 shop, and 8/4 common and dimension, none of the green chippable material is hogged for fuel; the over-sized chips are rechipped; and 100 percent of the green chippable residual can be converted into chips are rechipped; and 100 percent of the green chippable residual can be converted into chips of satisfactory quality.

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