Step 1 - Logging & Transportation – Timber harvesting, or logging, is the first step to getting a log to the sawmill. Trees are cut down using chainsaws during the logging process. This step is known as felling. Felling is essentially cutting down the tree and cutting it to length. Then, the log is delimbed and loaded on a truck for transportation to the mill. Once at the mill, the logs are unloaded and stacked into piles where they wait to be cut.
Step 2 – The Log Enters the Sawmill – The log is moved using a piece of heavy machinery and put on a belt where it awaits to be cut.
Step 3 – Debarking the Log – Once the log gets to the front of the conveyor belt, it will enter the mill to be debarked. A debarking machine is used to strip the log of its bark. Most sawmills use debarking machines like mechanical ring cutters, cambio drums, or water-jet blasters. Logs are also bucked or crosscut with a circular saw into specific lengths at this stage. The bark is then saved as it can be sold as mulch or used to fuel certain kilns at a sawmill.
Step 4 – Metal Detection – Each log will go through a large metal detector before being cut. Since trees can live for hundreds of years, there’s no saying what could be found in them. Often you will find nails, wire fencing, or other metals in the logs which can ruin your sawmill blades if they’re not caught beforehand. For the logs to have metal in them, the metal will either be removed, or the log will be cut into smaller sections so as much as possible can be salvaged.
Step 5 – Merchandising the Log – Makes sawmills much more efficient. Lasers scanning or camera viewing estimates the raw log for its maximum cut value. This information determines what sizes of timber, dimensional lumber, and boards can come from a particular log. Merchandising takes in more than just the log’s length and girth. It assesses each log for market conditions and standing orders.
Step 6 – Head Rig Sawing – “The heart of the sawmill” - Logs enter the head rig saw by getting clamped on a conveyor belt where the head rig blades move through the log.
Step 7 – Canting – The head rig cuts the log into sections called cants. The first or primary breakdown is called the best opening face (BOF). This sets a flat surface to square the work for secondary cants that turn into rough sizes for finished lumber products. Waste sections, or slabs, from cants are recycled into chips, pellets, or mulch.
Step 8 – Resawing – Cants that enter the resawing stage are usually being milled into rough cut lumber. The resaw uses multiple bandsaw or gang saw blades to cut the log into the boards that were merchandised.
Step 9 – Edging the Log – The lumber gets its sides cut. This squares up the log so that it fits a specific grade or width.
Step 10 – Trimming – The trimmer is used to cut the lumber to length. The length will vary based on the order or lumber size.
Step 11 – Grading the Lumber – The actual milling process is now complete. The lumber is ready to be graded. This is essentially a process for quality control. Since most sawmills won’t plane lumber and only sell rough cut, the grade is usually known as “FAS”.
Step 12 – Drying – Many sawmills don’t use a kiln and will just let their lumber air dry. Others buy kilns which can speed up the drying process significantly and increase the value of the lumber.
Most commercial sawmills specialize in processing either softwoods or hardwoods. A few sawmills tool up for both tree types, but that’s not common. The residential and light commercial construction industries primarily use softwood lumber for framing and rough carpentry. Hardwood materials are used for furniture and finished products, including flooring, staircases, and plywood veneer panels.
Three main lumber products come from a sawmill production line.
- Timbers – large-cut - end-products >5” thick – beams and posts
- Dimensional – most common – 2-5” thick and 2-12” wide – plate, joist, stud, header, and rafter
- Boards – Thin cuts – ¾-1” thick – 2-12” wide – sheathing, planking, pallets, crates, furniture frames
Specialized shapes – interlocking tongue and groove, shiplap edges, rounding profiles
Sawmills require power for other reasons besides turning blades and running conveyors. They need electrical power to operate advanced computerized systems for optimizing cuts, Programmable Controllers, Human Machine Interfaces, Variable Frequency Drives, Motors, etc.
There are roughly 500 lumber manufacturing facilities in the USA. Oregon constitutes 16% of the nations’ softwoods followed by Washington, Georgia, Alabama, California, Arkansas, Mississippi, Idaho, North Carolina, and Texas. The top four largest softwood sawmill companies are: Weyerhaeuser, Georgia-Pacific, West Fraser, and Sierra Pacific.
A cant is a sawn log that is sent to another machine for additional processing or sold as a large slab to be used as a building log
Sawmill workers have many titles: sawing machine setters, operators, tenders, sawyers, lumber mill workers, timber mill workers, sawmill yard workers, wood machinists, or wood processing workers.
The first log cut above the stump is called a butt log or butt cut. Butt off refers to cutting a piece of a log due to a defect. Most of a tree’s value is in the butt log.
A stack of lumber is a charge, which refers to a stack that has been processed in a dry kiln. If not dried in a kiln it is simply called a stack.