Hello taj,
And thanks for an interesting question.
A great place to start for questions like this is How Stuff Works at
www.howstuffworks.com . It seems that
http://www.howstuffworks.com/question154.htm , has a very similar
question for their question of the day on this particular day. They
say:
"Plywood is a building product that is common in the United States.
It's used in everything from furniture to house construction. The big
advantages of plywood include:
Standard size (4 feet x 8 feet is the common size in the U.S.)
Low cost for the size
Strength
Stability (warping and shrinkage is much less of a problem)
If plywood did not exist, you would end up making the same size piece
of wood from a collection of flat boards. That approach would be a lot
more expensive and not nearly as strong or stable.
To make plywood:
A log is softened with steam and then mounted on a lathe.
A long knife peels off a thin layer of wood in a continuous veneer
sheet. Once dried, a thin veneer sheet like this is very strong in one
direction (along the grain) and very weak in the other (across the
grain).
Several layers of veneer (generally five or seven) are layered
together with the grain direction alternating between the different
layers. Glue is used between the layers.
The stack is heated and pressed to form a rigid panel.
Because the grain direction of the layers of veneer alternate, the
panel is extremely strong in all directions. "
As you can begin to see, I think manufacturing of one's own plywood
would be cost prohibitive and require machinery and raw material not
usually found outside of large industrial plants and mills.
There is a link from this page to an article that appeared in the San
Diego Earth Times in March of 1998, PLYWOOD: Lurid Tales of Grains and
Glues. Here they say, from the history of plywood:
"It wasn't until the Industrial Revolution met the great forests of
the Pacific Northwest, however, that plywood made its mass-market
debut. The prototype panels were trotted out for the 1905 World's Fair
in Portland, produced one at a time, clamped with house jacks and held
together with animal glue which stank so bad that the workers had to
leave the mill frequently in search of fresh air. Since then, plywood
has become so widely used that in 1995 enough was produced worldwide
to cover a football field to a depth of eight miles..."
"The process of making plywood has become ever more sophisticated. To
start with, logs are cut to lengths of eight-and-a-half feet, stripped
of their bark and steamed to soften the wood. Next, they are mounted
on a lathe and spun at a few hundred revolutions per minute. A sharp
knife peels the spinning log into a single running strip of veneer
between one-tenth and one-quarter of an inch thick, depending on the
kind of plywood being made. The process is so quick that a
medium-sized log, some two feet in diameter, can be reduced to about
400 feet of tenth-inch veneer in a matter of ten or fifteen seconds.
Because the log is sliced with a knife, none of it is lost to sawdust,
although some is wasted in the process of reducing an irregularly
shaped log to a true cylinder. Over time, systems have improved to
discard less and less of the center core at the end of the process.
Previously, veneer lathes would stop peeling when the remaining core
was just large enough to make a pair of two-by-fours or a fence post.
New technologies allow veneer-makers to peel logs down to a core
barely thicker than a broomstick.
Once veneers are made and trimmed to standard lengths, they must be
handled carefully so they don't tear. The sheets are dried in a kiln,
and some are then patched. Higher grades of plywood must have all
their knots cut out and plugged with any of the standard-sized wood
patches, such as the familiar football- or eye-shaped repair.
The sheets of veneer are then laid up in stacks and glued, with the
better-looking veneers on the face and back, and the unappealing,
irregular or knottiest sheets in the center. The glued sheets almost
all made in the familiar four-by-eight-foot size are then sandwiched
for about five minutes in a hot press. Some final repairs are made
with resin, the panel is sanded, and it's ready for use."
So, you can see that much space and equipment will be needed in this
process.
The Canadian Plywood Association has a series of pictures on the
manufacture of plywood at
http://www.canply.org/products/manufacture_process/manufacture01.asp .
Here, in a series of pictures, you can see the vastnees of space
required as well as the heavy machinery to move logs, heat and steam
woods and glue and pressure treat the veneers into plywood.
Another good resource and explanation of the process can be found at
Veneernet.com http://www.veneernet.com/plywood.html - Plywood
Manufacturing.
If the above has not convinced you that this is a major undertaking
and you should be shopping your local home improvement store or lumber
yard for your plywood needs, than you might want to visit the Open
Directory pages on woodworking machinery at
http://dmoz.org/Business/Industrial_Goods_and_Services/Machinery_and_Tools/Woodworking_Machinery/
. Here you will find links to things such as kilns for drying of logs
and veneers and companies such as GRENZEBACH AKI CORPORATION that
manufacture these devices.
Another example of a link to be found here is
http://www.larsen.com.tw/leco.htm , LECO Machinery Co, LTD, a
manufacturer of Veneer Rotary Lathes, Core Builders, Glue Spreaders,
Cold Presses and more for your plywood factory.
And a number of sites such as Woodquip at http://www.woodquip.com/
deal in the sale of used equipment for plywood manufacture. As a
matter of fact, Machinery Masters deals with entire plants for sale,
mostly from repossessions! They can be found here
:http://www.machinerymasters.com/ and all components of this
particualr plant are shown at
http://www.machinerymasters.com/docs/liquidations/MustSell7.asp .
Search strategy: How to make plywood
plywood manufacturing
plywood equipment OR machinery
I hope this has provided you with an introduction to the steps
necessary to manufacture plywood and resources for both new and used
machinery and equipment needed in this process. If anything above is
unclear, please do ask for clarification.
Regards,
-=clouseau=- |
