|| Written by Kevin H. Touchette
The first sawmills were basic and rather simplistic buildings, equipped with a back and forth saw driven by hydraulic motors. First, sawmill held a central place in villages and were intended only for coastal residents. Moreover, the creation of cities such as Hull, Joliette, Grandes-Piles, Chicoutimi and Rivière-du-Loup are the result of the appearance of these mills.
They were traditionally located near a stream, which could thereby contribute to the delivery of logs by floating and could produce approximately 500 timber planks per day. To export, larger mills produced more logs and planks a day, with more careful techniques and more efficient blades.
VIDEO : A film from 1935 posted on YouTube by Library and Archives Canada shows the Douglas Fir timber production in British Columbia. The heritage film, called Big Timber, explores how Douglas Fir was harvested and processed into wood products.
Thereafter, in the nineteenth century, the circular blades were used for ripping and rendering. The former blade has been substituted by the saw continuously rotating ribbon. To power the mill, steam was becoming more common, because it offered better performance and allowed installation sites outside near lakes or rivers.
Sawmills were dangerous places, and many workers died under the sharp teeth of the blades. Despite the ban on employing children under 12 years old, they were sought for their small size: they were asked to infiltrate the inner workings and unlock sawing machines, which led to several tragedies.
After 1945, mechanization and new technologies are arriving. The electricity replaced steam, and many sawing machines appeared. Becoming more automated, sawmills see the need for human labor decreasing, causing a rise in unemployment in many regions. Today, the mills are fully computerized, require few workers and have a huge performance.
TWENTY-FIRST CENTURY MILL
Today’s sawmills are therefore defined as industrial sawing facilities that are of primary wood processing industries. They provide semi-finished products which are usually intended for secondary processing industry (construction, renovation, woodwork, carpentry, etc.) that is commonly called the lumber industry.
In Canada, lumber production comes mainly from coniferous trees that make up the bulk of the country’s forests. Hardwood species (maple, cherry and oak) are generally excluded: its use is generally reserved for the manufacture of floors and furniture, and other so-called finishing works. Spruce, pine and cedar are the main species processed into lumber in Canada.
GENERAL WOOD SAWMILL OPERATIONS
The mills purchase their supplies of rough wood more often from forestry. A sawmill mainly includes :
- A log yard where raw wood is stored;
- One or more sawing lines ensuring the cutting of wood and sorting of products;
- A timber park where boards and other products are arranged and stored.
The logs are usually brought to the mill by logging trucks and stored outside in what is called the log yard which forms the company’s stock. At this point, an operator is involved in purging some logs because some of them are split, suffer from rot, etc.
SAW BENCH AND STORAGE
Logs (beads) are then brought on the saw bench to be debited one by one. In response to orders received by the company, the operator seizes the thickness at the board level in a computer.
In the most modern facilities, the log passes in front of several cameras that will measure it in order to optimize the production of planks and obtain the best raw material yield / finished product. Depending on the facilities, the bead passes several times at the band saw (or head saw) if the bench only has one saw, or passes only once if several saws are associated with each other.
Sawing logs must be cut longitudinally by parallel plans to an approximate axis. First and last blade of wood are slabs that essentially contain bark and sapwood and go directly to waste. The following bands are called pads. Wood is sawn when green, means waterlogged. One of its properties is losing part of its volume during drying.
Another part of its volume will also disappear during subsequent development sawing operations (currying, planning). The boards are then carried to be stored before delivery. They are obviously classified according to size. The storage conditions are important because depending on the temperature and humidity, the wood may expand or contract.