Sawmilling

the production of lumber (beams and boards) from logs. Logs are processed at sawmills, which comprise wood-cutting and seasoning shops, raw-material and lumber-storage areas, and auxiliary shops.

Logs are unloaded, sorted by size and quality, stacked for winter storage, thawed in winter, barked, and prepared for shipment to sawmills at woodyards. Cranes (cable, gantry, and power cranes), chain and line transporters, winches, log conveyors, sorting units, and heated pools are used in these operations. When logs are floated to sawmills, they are assembled, sorted, and unloaded on special sites.

In sawmills logs and beams are cut lengthwise and unedged boards are cut and planed. Band saws, circular saws, and gang saws are used for lengthwise cutting. Fully mechanized conveyors transport the product from the saws. Cutting machines process sawmill waste into commercial chips.

The lumber is sorted, crated, and transported by self-propelled carriers to the seasoning yard for open-air drying or to the seasoning shop for kiln drying. In seasoning yards lumber is stacked so that passages are left for raw lumber and dried products to be moved. In summer, surface antiseptics are applied before seasoning to protect the lumber from fungal infections.

Dry kilns intensify the seasoning process by circulating hot air or a mixture of fuel gases and air among the rows of stacked boards. At many mills commercial sawn timber, after drying, is finally sorted, surfaced, and compactly packed for shipping to consumers. The yield of lumber from logs is usually 60–65 percent.

Sawmills are often part of lumber combines and complexes.