Community Level Processing Flashcards
- thin slices of wood and sometimes bark, usually thinner than 3mm (1/8 inch), that typically are glued onto core panels to produce flat panels such as doors, tops and panels for cabinets, parquet floors
VENEER
- includes all processes from the time the log enters the yard to the time when veneer sheet is packed and ready to be transported
VENEER MANUFACTURE
VENEER MANUFACTURING PROCESS:
a. PREPARATION
b. DEBARKING
c. COOKING
d. SLICING/PEELING
e. DRYING
f. QUALITY CHECK
g. SPLICING
h. PACKING
- logs are classified by species and stored in the log yard. Further, they are kept under optimal humidity conditions by soaking them in ponds of water or spraying them with water
PREPARATION
- the bark is then peeled off while ensuring that evenness is maintained
DEBARKING
- in order to ensure uniform slicing, the logs are kept completely submerged in steamers at temperatures of 80 – 100oC for a period of 18 to 72 hours
COOKING
- pressure and knife bar settings are set to an accuracy of 0.1mm,one of the two types of veneer slicing machines – a horizontal/vertical slicing machine or a peeling machine – are set in motion
SLICING/PEELING
- the veneers which are still moist are dried in a jet drier which also has the effect of flattening them
DRYING
- an expert carefully assess the veneers for quality according to strictly quality standards
QUALITY CHECK
- veneer matching is undertaken using the application of heat and pressure to ensure consistent match is obtained
SPLICING
- is a technique used to connect two pieces of wood end-to-end
Splice
- the wood veneers are measured, labelled with indications of length, width, etc., packed with protective polyethylene and readied to be transported
PACKING
GLUED-WOOD PRODUCTS & WOOD COMPOSITES:
- Plywood
- Particleboard
- Fiberboard
- Woodwool Cement Board
- an assembled wood product usually made up of two or more layers of veneers held together by adhesives
Plywood
- a product made up of small particles of wood and/or fibrous agricultural materials bonded together with synthetic resin and cured under heat and
- a generic term for panel manufactures from ligno-cellulosic material combined with a synthetic resin or other suitable binder and bonded together under heat and pressure in a hot press
Particleboard
Types of Particleboard Density (PHILSA):
a. Low density particleboard – 400 – 600 kg/m3
b. Medium density particleboard – 640 – 800 kg/m3
c. High density particleboard – 880 – 1000 kg/m3
d. Extra-high density particleboard - >1,100 kg/m3
- sheets of varied densities, made from refined wood fibers or other ligno-cellulosic materials with the primary bond deriving from the arrangement of fibers and their inherent adhesive properties
Fiberboard
- a panel product made of either shredded wood, flakes/strands/splinters or particles of wood or agricultural residues bonded with ordinary portland cement with some mineral additives & cold pressed under low pressure & ambient temperature and resistant to fungus and termite attack
Woodwool Cement Board
- an assembled wood product usually made up of two or more layers of veneer held together by adhesives, where the grains of adjacent layers are perpendicular to each other
PLYWOOD
COMPONENTS OF PLYWOOD:
a. FACE VENEER
b. CORE VENEER
c. BACK VENEER
- usually the most beautiful and smooth side of plywood
FACE VENEER
- the veneer placed at the inner portions of plywood
CORE VENEER
- lower grade veneer placed at the back of plywood and is the rough side of the plywood
BACK VENEER
CLASSIFICATION OF PLYWOOD:
A. PHYSICAL CONSTRUCTION
B. TYPE OF GLUE-BOND
PHYSICAL CONSTRUCTION:
- All veneer plywood
- Battenboard
- Blockboard core plywood
- Comply
– consists of odd numbered sheets of veneers
All veneer plywood
– pieces of lumber, 2” – 3” thick are used as core veneers
Battenboard
– lumber trimmings, less than 1” thick used as core veneers
Blockboard core plywood
– veneer faces and a core consists of particleboard or hardboard
Comply
TYPE OF GLUE-BOND:
- Type I (Exterior)
- Type II (Interior)
- uses phenol formaldehyde resin adhesives
- plywood intended for permanent exterior use
- the bond should withstand all weather and water exposures
Type I (Exterior)
- uses urea formaldehyde resin adhesive
- bond strength should be maintained when occasionally subjected to thorough wetting and drying conditions
Type II (Interior)
