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Engineered wood
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Engineered wood, also called composite wood, man-made wood or manufactured wood, includes a range of derivative wood products which are manufactured by binding together the strands, particles, fibers, or veneers of wood, together with adhesives, to form composite materials.
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Encyclopedia
Engineered wood, also called composite wood, man-made wood or manufactured wood, includes a range of derivative wood products which are manufactured by binding together the strands, particles, fibers, or veneers of wood, together with adhesives, to form composite materials. These products are
engineered to precise design specifications which are tested to meet national or international standards.
Typically, engineered wood products are made from the same hardwoods and softwoods used to manufacture lumber. Sawmill scraps and other wood waste can be used for engineered wood composed of wood particles or fibers, but whole logs are usually used for veneers, such as plywood. Alternatively, it is also possible to manufacture similar engineered cellulosic products from other lignin-containing materials such as rye straw, wheat straw, rice straw, hemp stalks, kenaf stalks, or sugar cane residue, in which case they contain no actual wood but rather vegetable fibers.
Characteristics
Engineered wood products are used in a variety of ways, often in applications similar to solid wood products. Engineered wood products may be preferred over solid wood in some applications due to certain comparative advantages:
- Because engineered wood is man-made, it can be designed to meet application-specific performance requirements.
- Large panels of engineered wood may be manufactured from fibres from small diameter trees.
- Small pieces of wood, and wood that has defects, can be used in many engineered wood products, especially particle and fiber-based boards.
- Engineered wood products are often stronger and less prone to humidity-induced warping than equivalent solid woods, although most particle and fiber-based boards readily soak up water unless they are treated with sealant or paint.
Engineered wood products also have some disadvantages:
- They require more primary energy for their manufacture than solid lumber.
- The required adhesives may be toxic. A concern with some resins is the release of formaldehyde in the finished product, often seen with urea-formaldehyde bonded products.
- Cutting and otherwise working with engineered wood products can expose workers to toxic constituents.
The types of adhesives used in engineered wood include:
Urea-formaldehyde resins (UF): most common, most cheap, and not waterproof.
Phenol-formaldehyde resins (PF): yellow/brown, and commonly used for exterior exposure products.
Melamine-formaldehyde resin (MF): white, heat and water resistant, and often used in exposed surfaces in more costly designs.
Methylene diphenyl diisocyanate (MDI) or polyurethane (PU) resins: expensive, generally waterproof, and do not contain formaldehyde.
A more inclusive term is structural composites. For example, fiber cement siding is made of cement and wood fiber, while cement board is a low density cement panel, often with added resin, faced with fiberglass mesh. Plastic extrusion mixes of wood fiber and thermoplastic, such as polyproplyene, has given rise to decking and railing material resistant to weather and is steadily replacing rot resistant wood.
Types
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