Definition of term
The term ‘wooden materials’ comprises various products that are manufactured through taking apart wood and subsequent joining it together, mostly under pressure and addition of other materials (for example synthetic resins, mineral binding agents and other additives). Among the wooden materials are primarily the materials in the form of boards (plywood, chipboard, fibreboard) as well as the correspondingly built formed parts of plywood, shavings or fibres. The advantages of the wooden materials compared with solid wood are particularly the homogeneous structure and thus the more steady behaviour, the availability of larger dimensions and the higher utilisation of raw material.
is composed of at least three plies of wood glued on top of each other, whereat the directions of fibre of adjacent plies are staggered by 90°. Depending on the kind of intermediate ply it is differentiated between:
- Veneer plywood
Intermediate ply of veneer, all veneer plies of the same wood species
- Block/strip plywood
Intermediate ply of 24 – 30 mm thick wooden rods glued with each other (former description: wood-core plywood). If the wooden rods of the intermediate ply are not glued it is spoken about a bar panel.
- Lamin plywood
Intermediate ply of approx. 8 mm thick the sheets of veneer standing upright to the board level
- Compound plywood
besides the veneer plies it also has at least one additional ply consisting of another material
The boards glued of several veneer plies are also described as compregnated materials. These materials also include the laminated wood where the single veneer plies are glued collateral to the fibre, the star plywood that is made up of at least 5 veneer plies glued staggered at an angle of 30 – 45°, as well as the highly compregnated synthetic-resin-compressed wood where at least 5 veneer layers of copper beech imbued with synthetic resin are pressed with each other under high pressure.
is produced through pressing of wood shavings and/or other fibres of wooden kind (for example shives of hamp or flax, annual plants) with organic adhesives (synthetic resins) or with mineral binders (for example gypsum, cement). The gross density is between 480 – 750 kg/m³. According to the arrangement of the shavings respectively the manufacturing processes it is distinguished between:
- Flat pressboards
Shavings predominantly directed parallel to the board level. Structure one- or multi-layered, mostly three-layered. Through special spreading technology the coarser shavings get into the middle of the board, the finer shavings get into the cover layers.
Examples for types of board:
Flat pressboards for universal purposes
Flat pressboards with a fine splinted surface
- Extruded-particle board
One-layered boards where the faces of the shavings are mostly vertically to the board level. Manufactured through continuous stuffing in a vertical press shaft.
Extruded-particle tubular board
Extruded-particle plain sheet board
- Mineral bonded chipboard
Boards pressed with mineral binders. These types of board include the chipboards bonded with cement, magnesite and gypsum. The advantages of these boards are their high resistance to humidity and fungi as well as their good behaviour in fire. The disadvantages are the more difficult machinability, the lower bending strength and the high weight (850 – 1200 kg/m³. Exception: Wood wool lightweight building board, approx. 360 – 570 kg/m³).