wood presentation

7/31/2019 Wood Presentation

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Wood


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Wood


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Cross section of a tree trunk


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Hardwood and Softwood


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Hardwood

Hardwood

is wood from angiospermtrees(more strictly speaking non-monocot angiospermtrees). It may also be used for those trees themselves: these are usually broad-leaved; in temperate and boreallatitudes they are mostly deciduous, but in tropics

and subtropics mostly evergreen.

Applications

Hardwoods are employed in a large range of applications including: fuel, tools,construction, boat building, furniture making, musical instruments, flooring, cooking,

barrels, manufacture of charcoal, etc.
http://en.wikipedia.org/wiki/Woodhttp://en.wikipedia.org/wiki/Flowering_planthttp://en.wikipedia.org/wiki/Treehttp://en.wikipedia.org/wiki/Monocothttp://en.wikipedia.org/wiki/Temperatehttp://en.wikipedia.org/wiki/Boreal_ecosystemhttp://en.wikipedia.org/wiki/Latitudehttp://en.wikipedia.org/wiki/Deciduoushttp://en.wikipedia.org/wiki/Tropicshttp://en.wikipedia.org/wiki/Subtropicshttp://en.wikipedia.org/wiki/Evergreenhttp://en.wikipedia.org/wiki/Fuelhttp://en.wikipedia.org/wiki/Toolhttp://en.wikipedia.org/wiki/Constructionhttp://en.wikipedia.org/wiki/Boat_buildinghttp://en.wikipedia.org/wiki/Furniturehttp://en.wikipedia.org/wiki/Musical_instrumenthttp://en.wikipedia.org/wiki/Wood_flooringhttp://en.wikipedia.org/wiki/Campfire_cookinghttp://en.wikipedia.org/wiki/Barrelshttp://en.wikipedia.org/wiki/Charcoalhttp://en.wikipedia.org/wiki/Charcoalhttp://en.wikipedia.org/wiki/Barrelshttp://en.wikipedia.org/wiki/Campfire_cookinghttp://en.wikipedia.org/wiki/Wood_flooringhttp://en.wikipedia.org/wiki/Musical_instrumenthttp://en.wikipedia.org/wiki/Furniturehttp://en.wikipedia.org/wiki/Boat_buildinghttp://en.wikipedia.org/wiki/Constructionhttp://en.wikipedia.org/wiki/Toolhttp://en.wikipedia.org/wiki/Fuelhttp://en.wikipedia.org/wiki/Evergreenhttp://en.wikipedia.org/wiki/Subtropicshttp://en.wikipedia.org/wiki/Tropicshttp://en.wikipedia.org/wiki/Deciduoushttp://en.wikipedia.org/wiki/Latitudehttp://en.wikipedia.org/wiki/Boreal_ecosystemhttp://en.wikipedia.org/wiki/Temperatehttp://en.wikipedia.org/wiki/Monocothttp://en.wikipedia.org/wiki/Treehttp://en.wikipedia.org/wiki/Flowering_planthttp://en.wikipedia.org/wiki/Wood


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Types of hardwood and their uses

Alder for making furniture and electric guitars

Ash - walking sticks

Beech - parquet flooring and railway sleepers

Cherry - smoking pipes

Elm - used in wheel making and ship building

Most Common Uses for Hardwood Plywood

hardwood plywood is made from binding together three or more thin veneers/layersof wood with a strong adhesive. The resulting material has uniform strength--since itscomprising piles of wood are bound at right angles to each other. Hardwood plywood

is strong, durable and is resistant to cracking and splitting. The most common typesof wood used to make hardwood plywood include walnut, maple, mahogany, oak,birch and gum. Hardwood plywood panels come in a variety of thicknesses, rangingfrom 0.25 inches to 1.25 inches.


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Softwood

Softwoods come from coniferous trees which have needles instead of leaves.

Softwoods grow faster than hardwoods and so are cheaper and are easier to

work with as they are softer than hardwoods. Theses are supplied in standard

sections sawn and planned smooth. Softwood sizes are confusing because they

are smaller once they are planned.

Softwood properties:

Softwoods come from coniferous trees.

Softwoods are special because they dont loose their leaves.

Softwoods have needles instead of leaves.

Softwoods grow faster than hardwoods so are cheaper.

Often used as building material.

Trees grow tall and straight which makes


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Softwood


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Advantage & Disadvantage

Advantage of softwoods

It is cheap

It grow more quickly than hardwood

It is easily to work with

It has low density

Disadvantage of softwood It is easily damaged

It needs to be treat with preservative

It is quite tacky


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Trees


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Comparison


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Timber Conversion

Timber conversion means the sawing of logs into usable sizes with the minimum of waste.

Conversion of timber is done in sawmill. Methods of conversion

There are two main methods of conversion:

Plain sawing

Quarter sawing


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Plain sawingPlain sawing is also known as flat, through and through and slash sawing.Plain sawing is carried out on softwood, such as pine, cedar, whitewood and redwood.

Advantages of plain sawing:It is the simplest, cheapest and quickest method.Disadvantages of plain sawing:Because there are annual rings in the boards, the board warps and shrinks badly.Only the centre board has short annual rings and will stay flat.

Q t S i


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Quarter SawingQuarter sawing, also known as radial sawing, is a method of sawing roughly parallel to the medullar

rays with the result that the figure rays appear on the face of every board.

Quarter sawing is carried out on hardwood such as teak, oak beech and elm.

Advantages of quarter sawing:True quarter sawing produces boards with short annual rings.Less liable to warp and shrink.

Stronger.Produces attractive grains which is exposed by sawing along medullar rays of some HWsDisadvantages of quarter sawing:True quarter sawing is more difficult.More expensive.Slower than plain sawing.Produces a lot of waste


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Seasoning of Timber

Seasoning is the removal of excess of moisture from the wood by drying after conversion.

Unseasoned timber, green timber has 85% moisture content (MC).Seasoned timber has below 18% of MC for general use and 12% of MC for centrally heated

and air conditioned building.

Importance of seasoningCompared to unseasoned timber, correctly seasoned timber has an:Increased strength.Increased stability.Increased resistance to decay.


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Seasoning

Air seasoning (The natural method)

Boards are stacked in the open with sticks between them to allow air to circulate.

The stack is raised clear off the ground on piers.

Has a roof to protect it from the weather.

Ends of board are painted to prevent end grain drying more quickly than the rest of the boards.

Advantages:Cheap method.Needs little skilled attention.Disadvantages:It takes 3 to 5 years to dry.Moisture content can be reduces to 15-18%.


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Kiln seasoning (The artificial method)

Boards are stacked on trolleys with stick between them and pushed into a kiln.

Seasoning proceeds in 3 stages: Stage 1: Steam is injected at low temperature to force free moisture out of the wood

cells.

Stage 2: Steam is reduced and temperature is increased to dry wood.

Stage 3: Finally there is a flow of hot, almost dry air.

Advantages:Takes a few days or weeks.Kill insects in wood.Possible to reduce moisturecontent below 15%.

Disadvantages:Kilns are expensive to buildand run.


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Uses of seasoned timber

Seasoned timber is used in construction ofhigh quality furniture such as:

Chairs and tables Wardrobe and cupboards

Turnery and photo frames

Tools


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Finishing


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Manufactured

Board


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Manufactured Board


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Veneers


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Plywood


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Laminboard And Blockboard


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Chipboard


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Fibreboard (hardboard)


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Fibreboard (Softboard)


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Medium-Density Fibreboard (MDF)


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END

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