Plywood Manufacturing Process
1. The plywood manufacturing process begins with processing the
wood at the sawmill. When the raw logs are delivered to the mill, they
are sorted, typically by size and species of tree. Plywood can be made
with a large variety of types of wood. It is often made with pine, fir,
cherry, oak and maple. The uncut logs are then treated with water.
They may be soaked in hot water, exposed to steam or sprayed with
hot water, depending on the setup of the particular mill. Following this
log conditioning, the bark must be removed from the logs to
accommodate the lathing process. Most mills employ a debarking
machine for this process, which minimizes damage to the usable wood.
The logs are then cut to a length appropriate the mill's lathe. The
standard length is typically somewhere between 240 to 270 cm.
2. The next phase of the plywood manufacturing process is veneer
production. The logs which are, generally, still hot from the condition
process are then placed in either a veneer lathe or a veneer slicer. The
veneer is sliced off in one continuous piece. Typically, the veneer will
then be rolled onto spools. The veneer will be trimmed to the
appropriate size, which may be performed by hand or by a machine.
The veneer, which is still green wood now, needs to be dried. Different
mills are equipped differently, so the drying process can take two
routes. The veneer may be air dried outdoors or may undergo a kilndrying
process. The kiln is usually a closed system in which the
temperature is constantly controlled to remove water from wood.
3. The final phase of the plywood manufacturing process is the
actual assembly of the plywood. The veneer is glued along the edges to
form larger sheets of the veneer for use in plywood production. Large
sheets are then applied with an adhesive and stacked. On the outer
layers, the grain runs the length of the sheet. The grain of the individual
sheets alternates on the interior. The larger glued sheets are then run
through a press (most of which are heated) to dry the glue. Finally, the
wood is subsequently trimmed, sanded if and as necessary and graded