Plywood or ‘reconstructed /engineered wood’ is the result of a manufacturing process which joins thin layers or plies of wood veneer that are about 3 millimetres thick with adhesives and then compressed under heat. Resin and wood fibre sheets are well bonded resulting in a composite material. With each new layer of veneer added, the wood grains of the adjacent layers are turned 90 degrees to one another. The plywood’s strength is thus maximised and warping and twisting are prevented.
Plywood, as a building material is characterised by its versatility and is used in both interior and exterior applications. Because it is made in layers it is extremely strong but also light in weight. Inexpensive wood forms the interior layers of the boards and the outer veneer layers comes from more expensive wood that gives it the wood grain appearance.
Advantages of Plywood
Plywood is reasonably durable and offers an excellent foundation for construction.
● The criss-crossing of adjacent sheets makes it uniformly strong and gives it equal resistance in all directions.
● Its structural works are lighter than solid wood due to the resistance being equal.
● It is able to resist shrinking, swelling, bending, warping, cracking and other types of deformations.
● The criss-crossing of the layers means that the boards can be nailed or screwed near the edges without breaking or splitting.
● Thick wood can be cut into veneers and glued into plywood panels to be used in the manufacturing of furniture.
● Its manufacturing has resulted in the reduction or even elimination of residues (saw dust), helping in the conservation of wood
● Its manufacturing is an economical and effective method of wood utilisation.
● Modern architectural designs with curved surfaces can be easily obtained with the use of this versatile material.
● Lower quantities of glue are used in plywood panels.
Situations where Plywood may not be the most suitable material of choice...
● It may show up natural defects such as knots due to the sheets of veneer
● The edges of the board cannot be covered and the exposed parts are not pleasing to the eye.
● The layering effect in this material makes it porous and when exposed for a length of time becomes susceptible to water damage.
● It should be covered if left exposed outdoors to reduce the risk of water damage, causing the wood to become heavy when wet.
Applications for different types of Plywood
The spruce-pine-fir combination of spruce, douglas fir, cedar, pine and fir and redwood produces softwood panel. This plywood is best for industrial and construction applications.
This type is best used for home construction for ceiling, floors, walls and roofs and wind bracing panels, fencing and internal body work of vehicles.
Wood from the angiosperm trees are used to manufacture hardwood plywood. Hardwood plywood is very strong, stiff and is also characterised by a resistance to creep. It is best for heavy-duty applications because of its high planar shear strength and impact resistance.
This type is best used on the floors, walls and roofs of transport vehicles, container floors, heavy-duty flooring in factories and buildings, scaffolding materials, panels in concrete form work systems, wind turbine blades, high-end loud speakers, die-cutting boards, playground equipment, heavy-duty furniture, signs and fences for outdoor advertising, musical instruments, sports equipment, supporting structure for parquet and insulation boxes for LNG carriers.
The wood from the mied species is manufactured into tropical plywood. In terms of strength, density and evenness of its layers, it has a better performance and is of a higher quality than softwood plywood.
Due to its premium quality and strength, is best used in the construction of concrete and structure panels, container flooring, floor base, lamin board and as laminated veneer lumber (LVL)
Aircraft plywood is manufactured from mahogany and /or birch and bonding is done with adhesives, thus resulting in high strength material which is very resistant to heat and humidity. It was used in the making of World War II fighter aircraft
Marine plywood has few defects because it is made using face and core veneers. It is durable and resistant to delaminating and fungal attacks, thus able to last longer in humid and wet climates
In furniture manufacturing, the curved parts of the furniture are made with flexible plywood.
Decorative Type (overlaid plywood)
Utilises a multitude of underlying woods which includes, oak, red oak, ash, maple, birch and mahogany and various other local timber species.
Process of manufacturing Plywood
Video below shows the industrial processes involved in making this material