Manufactured boards types

DESIGN TECHNOLOGY
MATERIALS
MANUFACTURED BOARDS

Manufactured boards usually come in the standard size of 8' by 4' or 2240 mm by 1220 mm although other sizes can be obtained.

PLYWOOD
Plywood uses the fact that timber splits down the grain but not across the grain. If we glue alternate layers of wood with their grain at right angles to one another then we get a very strong material. It was not until the 1890s, with the introduction of rotary cut veneers, that plywood really come into its own and early uses included tea -chests and piano frames.

This interlocking sandwich gives plywood its high uniform strength and resistance to splitting.

Plywood is manufactured in large presses. Rollers apply adhesive and then pressure and controlled heat are used to bond the layers together. Waterproof glue is now used so that most plywood can be used outside. A variety of timbers are used depending upon the country of manufacture. Standard plywood is commonly available white (Birch) or red faced timbers (Mahoganies).
Veneered plywood is produced with a decorative face veneer in a variety of timbers, including oak, mahogany and teak.
Marine plywood is made from mahogany veneers and waterproof glue for outdoor use including boat building.

BLOCKBOARD
Plywood is expensive to manufacture in thicknesses over 12 mm. Blockboard is often used as a substitute when built up boards of greater thickness are required.
Blockboard consists of a solid timber core made up of parallel strips of softwood, 20 - 25 mm in width, sandwiched between two outer facing veneers whose grain runs at right angles to the core. These thin strips make a stable, strong slab core and are usually of pine or spruce, though in some countries hardwood is used. The facing veneer can be of birch or mahogany. 18 mm is a common thickness in this material. More decorative, and expensive, outer veneers are often added to give a better appearance.

CHIPBOARD (PARTICLE BOARD)
Chipboard, as its name suggests, is made from wood particles from all hardwood and softwood waste bonded together with adhesive.
The small particles give no grain direction and make these boards equally strong in all directions. The boards are produced by highly automated presses which press the boards to the correct thickness and heat is applied to set the adhesive..
Chipboard is relatively inexpensive and has a variety of uses from packaging to furniture and kitchen worktops. It is often finished either with a veneer of wood or a coating of plastic (melamine).

HARDBOARD
Hardboard provides a cheap, light material, made from wood fibre which is obtained from wood chips or pulped wood waste. It is pressed between steam heated plates to give large, flat grainless sheets with one smooth, glossy face and a rough patterned, textured surface. It is only made in thin sheets - 3 mm being a common size. It is used a lot for the backs of inexpensive cabinets. It is unsuitable for outdoor work.

MEDIUM DENSITY FIBRE BOARD
Medium density fibreboard has now taken over in many areas from chipboard as it is denser and has smooth faces, and is generally thicker and heavier than chipboard. It is very stable, being unaffected by changes in humidity. However it does absorb water and cannot be used outside. It takes paint and other finishes extremely well and the edges, unlike other manufactured boards, need no extra treatment so it is used much in the furniture industry.

INSULATION BOARD
Insulation board is also made from wood pulp but it is not so compressed. It has a low density, and is both light and weak. It is particularly suited to use on interior walls, where it is a good insulator for both heat and sound (e.g. acoustic tiles, notice boards).