Lumber is a general term that refers to a variety of lengths of timber used as building materials. Lumber pieces are cut lengthwise from tree trunks and are distinguished by having a square or rectangular cross-sections in contrast to pilings or poles, which feature round cross-sections.
The wood used as a building material dates back to written records. The first evidence of wood construction comes from a location close to Nice, France, where the post holes suggest that a structure 20 feet (6m) wide and 50 feet (15 meters) long was constructed there in the past 400,000 years using wooden posts to support it. The oldest structure of wood discovered intact is located in northwest Germany and was constructed around 7300 years old. By 500 B.C. iron saws, axes, and chisels were widely employed to shape and cut wood. The first mention of cutting wood with the sawmill, instead of using hand tools, originates in the northern part of Europe and dates to about 375. Sawmills were powered with water flowing through it.
Raw Materials
The woods that are used to make lumber are classified as softwoods or hardwoods. While the woods of many hardwoods are hard and the woods of a lot of softwoods are soft in nature, this is not the primary characteristic.
The majority of hardwood trees have leaves that are shed in the winter. Hardwood trees include oaks walnuts, maples, cherries, and birches. But they also include balsa which is among the softer and lightest of all woods. Softwood trees, on the other hand, are characterized by the appearance of needles rather than leaves. They don’t shed their needles in winter months, but are all year round and are often referred to as evergreens. They include pines hemlocks, spruces, firs, and redwoods.
The Manufacturing Process
Within the United States, most trees that are destined for cutting into lumber are cultivated in forests managed by the government, controlled by the timber company, or leased to the state. When the trees are at the right size they are removed and taken to a lumber mill, where the trees are cut to a variety of sizes of timber.
Felling
- The trees that are in the area are inspected visually and then marked as ready to be cut down or removed. If a road doesn’t exist within the region the trees are cut and graded with bulldozers. If construction is anticipated to last into the season of rain the road might be graded and culverts could be constructed over streams to avoid washouts.
- The majority of tree felling is completed using chain saws powered by gasoline. Two cuts are cut near the base with one cut on each side, in order to regulate the direction of the tree’s fall. When the tree is down it is cut off using chain saws then the trees are cut to suitable lengths for transport.
- In the event that the land is level, diesel-powered tractors also known as skidders can be used to transport fallen trees into an unloaded area to be loaded. In the case of steep terrain, the self-propelled yarder can be utilized. The yarder is equipped with the capability of telescoping its hydraulic tower, which can be elevated to an elevation of 110 feet (33.5 meters). Guy wires are used to support the tower and cables are dragged through the tower from its top to the steep slopes, to retrieve the fallen trees. The tree segments, also called logs are loaded onto trucks by using log loaders on wheels.
- The trucks drive along the road that is graded and onto public roads before heading to the mill. After arriving at the mill huge mobile unloaders eat the entire truck in one bite and then arrange it into large piles, referred to in log decks. The decks are regularly sprayed with water to stop the wood from shrinking and drying out.
Bucking and debarking
- Logs are taken off the deck of the log using loaders that have rubber tires and then put onto a conveyor chain which is then lowered into the mill. In some instances, the outer bark on the wood is taken away by using grinding wheels with sharp teeth or by a jet of high-pressure water. During this process, the log is rotated slowly around the long axis. The bark that is removed is then broken down and used to fuel the mill’s furnaces or sold as a decorative garden mulch.
- The logs are transported to the mill via the chain conveyor, and there they are stopped for a moment while a large circular saw cuts them to predetermined lengths. This process is known as Bucking. The saw is referred to as the one-time saw.
Headrick cutting large logs
- If the log is of an area larger than feet (0.6-0.9 meters) then it is taken off the conveyor, and then clamped onto the moveable carriage which slides lengthwise along a set of rails. The carriage can place the log longitudinally in relation to the rails, and turn the log around 90 degrees or 180 degrees in relation to its length. Sensors with optical sensors look at the log to determine the diameter at every end, the length, and any apparent imperfections.
- The hearing surgeon is seated in a closed booth next to a massive vertical bandsaw, also known as”the hearing. He examines the recommended cutting pattern on a TV monitor but relies more on his own experience to determine the cuts. Logs are fed in a lengthwise fashion into the bandsaw’s vertical section. It cuts first on the edge nearest to the user. This removes a chunk of wood referred to as the slab. The exterior surface of the slab reflects the curvature that was present on the original tree trunk.
- The carriage returns to its initial location then the log will be moved to the side.
or rotated to make further or rotated to make subsequent. The hearing sawyer has to constantly check the log for any internal flaws and alter the cutting pattern to ensure that each cut cuts the log more. In general, the thinner pieces that are intended to be turned into the board are cut off from the outside portion of the wood with fewer knots. Smaller pieces for dimensions lumber will be cut after to the center, while the inner portion of the log produces lumber for large pieces of timber.
- The hearing surgeon is seated in a closed booth next to a massive vertical bandsaw, also known as”the hearing. He examines the recommended cutting pattern on a TV monitor but relies more on his own experience to determine the cuts. Logs are fed in a lengthwise fashion into the bandsaw’s vertical section. It cuts first on the edge nearest to the user. This removes a chunk of wood referred to as the slab. The exterior surface of the slab reflects the curvature that was present on the original tree trunk.
- The carriage returns to its initial location then the log will be moved to the side.
or rotated to make further or rotated to make subsequent. The hearing sawyer has to constantly check the log for any internal flaws and alter the cutting pattern to ensure that each cut cuts the log more. In general, the thinner pieces that are intended to be turned into the board are cut off from the outside portion of the wood with fewer knots. Smaller pieces for dimensions lumber will be cut after to the center, while the inner portion of the log produces lumber for large pieces of timber.
Small logs are bandsawed
- Logs with smaller diameters go through a set of bandsaws which will cut them into nominal 1 inch (2.5 cm) or 2 inches (5 cm) or 4 in (10 millimeters) large pieces of thickness in a single pass.
Resawing
- The large pieces of wood cut from the head-rig saw, referred to as cants are laid out flat and transported via chain conveyors to bandsaws with multiple blades, where they are cut into needed widths.Then the outer edges are cut to a square. The pieces made from smaller logs can be passed through multiple-bladed bandsaws to cut them into the required width. When the logs are smaller enough to not require any more cutting, they could go through a chipper which will grind the uneven edges into squares.
Drying or seasoning
- The cut and trimmed pieces of lumber are then transported to a location to be dried and “seasoned.” This is essential to stop decay and allow the wood to shrink as it dried out.
Timbers due to their size make them difficult to thoroughly dry and are typically sold as wet as well as “green.” Other lumber can be dry-air-dried or kiln-dried, based on the moisture content of the piece. The dried lumber is stacked in a protected area, with spaces between each piece so that air can circulate. The woods that are air-dried typically have around 20 percent moisture. Kiln-dried lumber is stored in a closed area and between 110 and 180 degrees Fahrenheit (44-82degC), hot air circulates throughout the stack. Kiln-dried woods typically have lower than 15% water. They are typically used for flooring or moldings, as well as doors in which a minimum amount of shrinkage is needed.
Planing
- The pieces of lumber that are dried are sorted through planers in which cutting machines rotate, trimming the pieces down to their final dimensions, then smooth all four surfaces, then smooth the edges.
Banding and grade stamping
- Every piece of wood is inspected visually or mechanically and graded in accordance with the degree of imperfections present.
The grade is engraved on each piece, as well as information about the content of moisture, and a mill identification code. After that, the lumber gets packaged in accordance with the type of wood, grade, and moisture content. Finally, the bundle is then secured using steel bands. The bundle is then loaded onto a train or truck and then transported to an area where it is resold to clients.
Quality Control
There are a few pieces of lumber that are perfect. Although the greatest care is taken to minimize or eliminate defects in the process of cutting the lumber to the needed sizes, there is all the time some flaws. The amount and position of these imperfections determine the quality of the wood and the buyer must select the grade suitable for the specific use.
Conclusion
As the amount of old trees that are available for logging decreases so does the lumber industry’s capacity to cut specific pieces of wood to sizes that are needed to construct. A majority of the trees currently being logged are second-generation or third-generation trees which are smaller and younger in diameter than older trees. The younger trees also have an increased proportion of young wood which is less stable than older wood. Our company tackles this type of issue by developing an effective drying method with the vacuum oven. Contact us to discuss additional specifics.
