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Plywood Manufacturing
By: Group V
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Contents of the report
Introduction
Brief History
Types of Plywood
Types of Adhesives
Manufacturing Processes
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Introduction
PLYWOOD: AN IMPROVED WOOD
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In1500 B.C.,Egyptian craftsmen bonded thin pieces oebony wood to the exterior of a cedar casket found in the King Tut-Ankh-Amon
. In the 1600s, the Greeks and Romans made the decorating furniture with thin pieces of wood became knveneering, and the pieces themselves became known as ve
Until the late 1700s, the pieces of veneer were cut entihand
In 1797, Englishman Sir Samuel Bentham applied for covering several machines to produce veneers.
Brief History
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. In about 1890, laminated woods were first used to build doo
In 1928, the first standard-sized 4 ft by 8 ft (1.2 m by plywood sheets were introduced in the United States for ugeneral building material.
. In the following decades, improved adhesives and new metproduction allowed plywood to be used for a wide va
applications.
Today, plywood has replaced cut lumber for many conspurposes, and plywood manufacturing has become a muldollar, worldwide industry.
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Plywood
It is a manufactured wood panel made from thin of wood veneer
It is a sandwich of thin layers of wood held togethglue, with the grain of each layer at right angles to tthe one next to it.
Plywood is used instead of plain wood becauplywood's resistance to cracking, shrinkage, splittintwisting/warping, and because of its generallystrength.
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Plywood
It is flexible, cheap, workable, re-usable, and can u
be locally manufactured.
Plywood is also strong; since it consists of an odd nof firmly joined layers in which the grains are atangles to one another, it has nearly equal strength
directions.
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Layers of Plywood
Plywood may consist of 3, 5, 7, 9 oreven more plies or layers.
The innermost layer or center is thecore. On each side of the core are
crossbands.
The two outside layers are thefaces; these may be of decorativewood, if desired, thus supplying
beauty as well as utility.
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Types of Plywood
There are two types of plywood
A. Softwood Plywood
B. Hardwood Plywood
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What Are
Veneers?
In woodworking, veneerslices of wood, usually thinn(1/8 inch), that typically a
core panels (typically wboard or medium-density fproduce flat panels such and panels for cabinfloors and parts of furniture
Veneer is obtained eitherthe trunk of a tree or byrectangular blocks of woflitches
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SoftwoodPlywood
These are made of Dhemlock, pine, and othewoods.
Softwood plywood is mby gluing several laysoftwood veneers togetadhesive.
Softwood plywood is usesiding, sheathing, roof dconcrete form boards, flocontainers.
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SoftwoodPlywood
The interior grade hasoybean glue as the bonAlthough this type resists moisture for a w
prolonged or repeatedloses its strength and more suitable for buildings where moisexcessive
The exterior grade is bsynthetic resin gluewaterproof. .It is morthan the interior grade adhesive is more expenprocessing more complic
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HardwoodPlywood
Hardwoods generally corrdeciduous species. plywood commonly use woinclude oak, poplar, map
and larch.
Hardwood plywood in genmaterial of the cabindesigner, and architect. Itcolors and diversity of funlimited.
Hardwood is graded accits resistance to moistmoisture resistance of high, of Type II moderaType III low.
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Types of Adhesives
The type of adhesives used affects the ability of plyto resist moisture, bacteria and heat. The strength o
joint depends upon the fact that glue, while liquid,into the cavities of wood structure and then solidifies
The glues and adhesives used in woodwork and plyincludes animal, vegetable, casein, soybean,albumin, and synthetic resins.
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1. Animal Glues
These are among the oThey are made from hitrimmings or bones of the
Animal glues are usuallywater and melted. They shhot to prevent decombacteria.
For best results, the wopreheated before the glue
Because of their high glues are used only withand highly figured veneer
They have little, if any, moisture and are attacked
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2. Vegetable Glues
These are made from a usually the cassava root
They are inexpensive,
joints, can be used coldkept in good working cmany days.
Besides being difficult tbrush, however, they pieces of veneer and lacto water and bacteria.
Their use in plywood to indoor paneling and phumidity does not vary
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3. Blood AlbuminGlues
The blood of cattle is usource of these glues.
While their resistancis high, they are attack by bacteria. they stain veneer, havand require considerabpreparation for use.
When used cold, thesejoints of moderate when hot pressed, joinvery strong.
In former years textensively used manufacture of plywood, but now theonly to extend and foglues.
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4. Casein Glues
For moisture resistancasein glue obtained milk is used. This typinexpensive and easily
tends to dull the edgcarpenters and cabinetm
Since it may decay, a is usually added to pro
Although casein glue strength when woccasionally, it loses strcontinuous exposure to
Plywood made with finds widest use inside in places where moistuare not severe.
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5. Soybean Glues
This adhesive is madmeal that remains soybean has been squee
of its oil. It is almost as water-re
strong as casein glurequires a preservativdecay.
It is less expensive thatbut produces weaker used on dense hardwood
Serious staining occursused on thin veneers.
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6. Synthetic ResinGlues
Exterior walls, borefrigerator cars lininboth that retain str
durability under waconditions, even aftewetting.
For such purposes thresin glues, which ar
of the chemical labooutstanding.
These resins also resdecay.
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5. Soybean Glues
This adhesive is madmeal that remains soybean has been squee
of its oil. It is almost as water-re
strong as casein glurequires a preservativdecay.
It is less expensive that
but produces weaker used on dense hardwood
Serious staining occursused on thin veneers.
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The PlywoodManufacturingProcesses
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Step 1: LogDebarking andCutting The log emerges fbarker after h
been strippedbark.
It is also cut intolength to enable
processin
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Step 2:Log Heating The logs a
conditioned steam or hot w
improve peel q
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Step 3: Lathing At the lathe, ablade peels thnow called a
into a continsheet of ven
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Step 4:VeneerDrying The dryer redumoisture conDrying is don
uniform tempe
and also desmicroorgani
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Step 5: Gluingand assembly Wide cross core and long panelare layered an
to give the plygreater strengdimensional st
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Step 6: Pre-pressor Cold Press The Pre-press is uniexpands and stabilayer to give a waproduct. It also euniform spread
specially formulatedwithin the lay
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Step 7: Hot Press Each board is put seinto hot-presspolymerization at temperature. This
uniform density at
in the plywood. Afpressing the boards for 24 hour
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Step 8: DimensionCutting /Trimming The boards are thorizontallyvertically. A utechnique of
cutting is usedthe final cuttensure dimen
accuracy
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Step 9: Sanding Surface sandingin an automatibelt sanding mThis gives a s
surface to the pwhich helps insurface finish r
for interio
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Step 10:Packaging andShipping The plywood is
and dispatchedvarious destin
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The PlywoodManufacturingProcesses Video
Presentation