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MUHAMAD BASRI BIN MD DAUD

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SADAM BIN KAHAR

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WHAT IS PLYWOOD?

Plywood is panel product of peeled veneer layers glued together so that the grain direction of some wood veneers run perpendicular to and others parallel to the long axis of the panel

Plywood also claims a high versatility of end uses. Its relatively simple to manufacture and has many advantages over other wood converted products as well as some steel and sheet metal applications

Uneven number of veneer is often used (e.g. 3, 5, 7) *a symmetry makes the board less prone to warping.

Two outer veneers are called the face and back veneers and the middle veneer called the core veneer

TYPE OF PLYWOOD

1. Interior Plywood The interior plywood is used for construction that is carried

out inside a house. These plywood are not meant for external use, as they cannot stand excess moisture.

2. Exterior Plywood The exterior plywood is glued together with a gluing material

that can withstand moisture. Thus, it is used for constructions carried out outdoors or areas of little moisture.

3. Structural Plywood These are extra strong plywood's that are glued together with

an adhesive that holds the layers firmly. The structural plywood can be used for internal or external purposes. These are basically not meant to be seen and are mostly hidden behind other constructions.

4. Marine Plywood The marine plywood is fabricated with a superior glue that is

bonded tightly and resistant to water. It is the strongest, toughest and highest grade plywood.

PLYWOOD MANUFACTURIN

G PROCESS

LOG STORAGELOG

DEBARKING AND BUCKING

LOG HEATING (STEAMING

AND SOAKING)

VENEER DRYING

VENEER CUTTING

VENEER LAY UP AND GLUE SPREADING

PLYWOOD PRESSING

PLYWOOD CUTTING

PLYWOOD FINISHING

FINISHED PRODUCT

LOG STORAGE

Timber in log form - In general

criteria relates to log size, quality

and grades, log transport and

handling requirements, and log

protection and quarantine

The purpose of this operation is to remove

the outer bark of the tree without

substantially damaging the wood

After the bark is removed, the logs are cut

to appropriate lengths in a step known as

bucking

LOG DEBARKING AND BUCKING

The logs (now referred to as blocks) then are heated to improve

the cutting action of the veneer lathe or slicer - thereby generating

a product from the lathe or slicer with better surface finish

Blocks are heated to around 93°C (200°F) using a variety of

methods--hot water baths, steam heat, hot water spray, or a

combination of the three

The veneer log is temporally softened making it more plastic,

pliable and more readily peeled and the quality and quantity of

veneer recovered from heated logs is greater.

LOG HEATING (STEAMING & SOAKING)

After heating, the logs are processed to generate veneer

There are two method to produce veneer1. Slicing2. Peeling (Rotary cutting)

Slicing produce more decorative veneer than peeling method.

Decorative hardwood veneers are usually sliced much thinner than 3 mm (1/8 in.) thick.

VENEER CUTTING

Veneers are taken from the clipper to a veneer dryer

where they are dried to moisture contents that range

from around 1 to 15 percent.

Target moisture content depends on the type of resin

used in subsequent gluing steps. The typical drying

temperature ranges from 150° to 200°C (300° to 400°F)

Type of veneer drying are:

1. Jet Dryer

2. Microwave

3. High Temperatures Preheaters

4. Ultra-Violet

5. Infra-red

VENEER DRYING

Assembly of the plywood panels must be

symmetrical on either side of a neutral

center in order to avoid excessive

warping.

Resin is spread on two sides of one ply

of veneer, which is then placed between

two plies of veneer that are not coated

with resin

Type of glue spreading

1. Roller glue spreader

2. Spray coaters

VENEER LAY UP & GLUE SPREADING

The laid-up assembly of veneers then is

sent to a hot press in which it is

consolidated under heat and pressure

There are two type of veneer pressing

1. Pre-pressing

2. Hot pressing

Typical press temperatures range from

132° to 165°C (270° to 330°F) for

softwood plywood, and 107° to 135°C

(225° to 275°F) for hardwood plywood.

PLYWOOD PRESSING

The plywood then is taken to a

finishing process where edges are

trimmed

Besides, the plywood will be cut into

the size needed

VENEER CUTTING

The face and back may or may not

be sanded smooth

The type of finishing depends on the

end product desired

PLYWOOD FINISHING

ADVANTAGES OF THE PLYWOOD

1. High uniform strength

2. Availability of relatively large sizes

3. Economical and effective utilization of figured wood

4. Freedom from shrinking, swelling and warping

5. Non-splitting qualities solid wood splits fairly readily along the grain.

6. Ease of fabrication of curved surfaces

7. The conservation of timber by the elimination of the waste which

occurs in sawing (e.g. sawdust)

DISADVANTAGES OF THE

PLYWOOD

1. The layering effect in plywood makes it porous and susceptible to

water damage if exposed over time.

2. Plywood becomes heavy when wet and should be covered if left

outside to reduce the risk of water damage.

3. Plywood has lots of splinters on the edge after cutting.

4. Edges of board are unattractive and can't be covered

5. Not suitable for many joints

6. Still may contain natural defects such as knots due to the sheets of

veneer

APPLICATION OF THE PLYWOOD

Cabinet interiors and

exteriors

Desk and Table tops

Kitchen tops

Doors

Drawers

Furniture

Shelves

Wall Paneling

Interior panels

External cladding

Plywood sheets –

flooring

Bracing (shearwalls)

THANK YOU..