In the producing process, log cutting, peeling, dry,
handling, hot press, edge trimming, sanding affect the wastage. The
wastage is remains of processing (materiality) and shrinking
(immateriality). Wood wastage is related to the material,
specification of log, equipment capability, technology and
production specification.
1) Log cutting:
Usually import log length is more than 6 meters. Cutting
according to the technology required length and quality. The
cutting length should be product length add remains. For example,
product is 1220mm*2440mm, cutting length usually be 2600mm or
1300mm. log length, camber and demerit affect plywood output
directly. Remains are small wood pieces, truncations, sawdust, tec.
Log cutting wastage ratio is 3%-10%.
2) Veneer peeling:
Peeling is the most popular plywood producing process. Back
veneer thickness is about 0.6mm, core veneer and centre veneer
thickness is about 1.8mm.
3) Drying:
Veneer is moist. it should be dried according to the
technology requirement. After drying, it will shrink. Dimension
will become smaller. Veneer length, width, thickness will
shrink. Shrink wastage is related to wood material, moisture
containing, veneer thickness. Shrink wastage is 4%-10%.
4) Veneer handling:
Handling include cutting, putting veneer together and
mending. Cut zonal veneer into specification veneer or proper size
which can be put together. Narrow zonal veneer can be put together
into one veneer. Veneer with demerit can be mended to be qualified.
Wastage in this part related to log material, peeled veneer
quality, dried quality, and worker operation skill. Wastage ratio
is 4%-16%. Import veneer processing plywood wastage ratio is
2%-11%.
5) Hot press:
Veneer be glued and stacked, then glue together under set
temperature and pressure by hot press. As veneer temperature and
moisture containing changes, veneer will shrink. Shrink
wastage is related to temperature, pressure, hot press time, wood
material, moisture containing, wastage ratio is 3%-8%
6) Edge trimming:
Trimming the edge of the plywood flank from hot press to
qualified plywood board. Remains related to process remains and
product dimension. Production is bigger, wastage is smaller.
Wastage ratio is 6%-9%
7) Sanding:
Sanding plywood surface to make it good. Wastage is powder.
Veneer quality is good, sanding is less. Wastage ratio is 2%-6%
8) Warehousing:
Plywood is packing in palletize or in bulk.