Materials Proprieties Technologies 1 ESO
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LET’S CHECK!! If glasses were made of opaque plastic, we would not see anything. If umbrellas were made of lace fabric, we would get wet because it’s a permeable material. If it rained on these paper shoes, our feet would get wet because paper is a permeable material. If keys were made of glass, they would break because glass is a fragile
WHAT DID WE LEARN?
WE CHOOSE THE MOST SUITABLE MATERIAL TO MANUFACTURE AN OBJECT LOOKING AT ITS
PROPERTIES
1 . PHYSICAL/CHEMICAL PROPERTIES TRANSPARENCY Capability of a material to let the light through and the objects clearly seen. A material can be: Opaque,
translucid or transparent
Remember the names of the properties: Opacity Translucidity Transparenc y
1 . PHYSICAL/CHEMICAL PROPERTIES Density: The relationship between mass and volume. It is the mass per unit volume of a material. d=density m=mass V=volume
The cork and the lead have got the same mass. But the leadhas less volume because it is more dense.
Which is more dense?
1 . PHYSICAL/CHEMICAL PROPERTIES
The materials that are higroscopic are used to waterproof tests.
Higroscopic materials absorb water as for example cellulose and silica gel.
little make
1 . PHYSICAL/CHEMICAL PROPERTIES Dilation Coefficient: It is to increase the volume that is produced in the materials with temperature changes. expansion joint
The expansion joint is very important to keep variable size in a structure.
1 . PHYSICAL/CHEMICAL PROPERTIES
1 . PHYSICAL/CHEMICAL PROPERTIES THERMAL CONDUCTIVITY Capability of a material to transmit the heat through it. A material can be: Thermal
insulator or thermal conductor
1 . PHYSICAL/CHEMICAL PROPERTIES ELECTRICAL CONDUCTIVITY Capability of a material to transmit the electricity through it. An object can be: Electric
insulator or electric conductor
1 . PHYSICAL/CHEMICAL PROPERTIES ACUSTIC CONDUCTIVITY Capability of a material to transmit the sound.
1 . PHYSICAL/CHEMICAL PROPERTIES OXIDATION Capability of a metal to change its composition under the presence of water or oxygen. A metal can oxidize easily or be stainless
1 . PHYSICAL/CHEMICAL PROPERTIES PERMEABILITY Capability of a material to let the water through. A material can be: Permeable
or impermeable (waterproof)
2. MECHANICAL PROPERTIES ELASTICITY Capability of a material to change shape under a force and then return to its original shape when we stop the force. A material can be: Elastic
or rigid
2. MECHANICAL PROPERTIES PLASTICITY Capability of a material to change shape forever and to not come back to its original shape. An object can be: Plastic
or rigid
2. MECHANICAL PROPERTIES HARDNESS Resistance of a material to scratching, cutting or bending. An object can be: Hard
or soft
2. MECHANICAL PROPERTIES TOUGHNESS and FRAGILITY Capability of a material to deform without fracturing when we hit it. An object can be: Tough
or fragile (brittle)
Compression
Traction
Flexion
Torsion
Shear
3. MANUFACTURINGNPROPERTIES FUSIBILITY Capability of a material to melt (turn from solid to liquid) under high temperatures. Materials: Melt
at different temperatures
Materials that don’t melt, but burn, are: Combustible
3. MANUFACTURING PROPERTIES WELDING Welding is a process to join materials (metals and plastics mostly) through local fusion between two pieces. A material can be: Weldable
or non-weldable
3. MANUFACTURING PROPERTIES MALLEABILITY Capability of a material to being hammered into thin sheets. A material can be: Malleable
or non-malleable
3. MANUFACTURING PROPERTIES DUCTILITY Capability of a material to being streched into thin wires or threads. A material can be: Ductile
or non-ductile
3. MANUFACTURING PROPERTIES
3. MANUFACTURING PROPERTIES SLICEABLE Capability of a material to be cut
3. MANUFACTURING PROPERTIES POLISHABLE Capability of
a material to be polished
INTERIOR MATERIAL & TECHNOLOGY- 1 S.E.M.- 01 AAERT _SCHOOL OF INTERIOR DESIGN
Wood Task – name 10 objects made of wood that is in close proximity to you.
AAERT _SCHOOL OF INTERIOR DESIGN
Wood Can you name any types of wood? pine, oak, ash, teak, mahogany, maple, rose wood, beech, Babul, Bamboo, walnut, cherry, zebrawood, balsa, Deodar, Sal…….
pine
oak
beech
walnut
maple
zebrawood mahogany
ash
Can you think of words that describe wood? warm, smooth, strong, flexible, strong, hard, soft, rough, …. AAERT _SCHOOL OF INTERIOR DESIGN
Introduction • •
Derived from the word timberian , that means to build Denotes wood which is suitable for building or carpentry.
•
Three terms to be known in connection to the timber. – Converted timber: sawn and cut into suitable commercial sizes. – Rough Timber: obtained after felling a tree – Standing Timber: Timber contained in living tree Valuable properties: » Low heat conductivity » Ability to mechanical working » Small bulk density » High Strength Drawbacks » Decay » Inflammability » Fluctuation in properties due to changes in moisture
•
•
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Classification Trees Exogenous They increase in bulk by growing outward and distinct consecutive rings are formed every year in the horizontal section of the tree
Endogenous They grow inwards and fibrous mass is seen in their longitudinal section e.g. bamboo, cane , palm
Conifers
Deciduous
-Also Known as ever green trees. -Leaves do not fall till new one are grown.
They increase in bulk by growing outward and distinct consecutive rings are formed every year in the horizontal section of the tree
Soft Wood -Light colored -Resinous -Light in weight and weak -Poor fire resistant -Strong in direct pull and week for resisting thrust or shear -Eg. chir, devdar, fir, kail, pine spruce etc
Hard Wood • Close grained •Strong •Heavy •Dark colored •Durable •Non resinous •Do not show distinct annual rings •Eg. Babul, mahogany, oak, sal , teak rose wood etc
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Sapwood •The
softer living portion younger, of wood the cambium between heartwood. and •Usually lighter in color, permeable and less more durable.
Xylem •The woody tissue
of a tree that provides and conducts water support and mineral nutrients from the roots upward
Inner Bark •A Layer of tissue that carries food from the leaves to the growing parts of the tree. •Also Phloem called
Annual Ring •A Concentric layer of wood during a produced single year’s temperate growth of tree •It is also known as Growth ring.
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Pith
Bark •The
Tough external a woody covering of stem, branch root, composed of or a layer living inner phloem and called an outer bark of corky, dead tissue.
•The
innermost central portion of a tree is called pith or medulla. •Varies in size and shape from tree to tree. •It is a soft part about first which takes place growth in a newly formed stem
Heartwood •The older harder ,
inactive core of a tree, usually darker denser and more durable the than surrounding wood sap •They are the inner annual rings •Imparts rigidity.
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Elements of tree
AAERT _SCHOOL OF INTERIOR DESIGN
Elements of tree PITH
CAMBIUM
OUTER BARK INNER BARK
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Identifications of Timber •
General Properties Color a darker color in wood indicates greater durability. Odor – it is present only on freshly cut trees. Hardness – is the ability of wood to withstand indentations caused by harder bodies. Density – densest woods are generally the strongest. Grain - Depending on the actual alignment, the grain may be straight, spiral, interlocked, wavy or irregular. Spiral Grain Interlocked Grain Wavy Grain Texture - In hardwoods, the texture depends upon the size and distribution vessels and rays. In softwoods, it is determined by the size and distribution of tracheid. AAERT _SCHOOL OF INTERIOR DESIGN
Identifications of Timber • • • •
Workability- the relative case in which wood is shaped cut and fastened together than the others. Warping- is the general term used to describe any variation from a true surface. Moisture content- is a percentage of the mass of water over the mass of wood fiber in a piece of timber. Specific Gravity- is the ratio found by dividing the weight of a substance by the weight of an equal volume of pure water
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Mechanical Properties •
• • • •
• • •
Tensile Strength – Timber is stronger in tension along the rain but it’s quite difficult to determine this because of the difficulties in conducting test. Compressive Strength – The strength along the grain is important for columns, props, and post. Shear Strength – Shear strength is important in the case of the beam and slabs. Bending Strength– This refers as the strength of the timber as a beam. Cleavability – High resistance for cleavage is important for nailing and screwing while low splitting strength is important for used as firewood. Torsion Strength – is used to determine the torsion strength of the timber and the specimen is loaded up to failure. Hardness – is important in case of timber for paving blocks flooring bearings and other similar purposes. Stiffness - This property is important to determine theOF deflection AAERT _SCHOOL INTERIORofDESIGN a timber under a load.
DEFECTS AND DECAY IN TIMBER • • • •
CENTRE HEART/HEART SHAKES BOW KNOTS CUPPING
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Defects in timber Timber is a natural material that is prone to defects. One of these is the tendency to split if it is put under stress from rapid drying or de-lamination of the growth rings. These defects are all known as ‘Shakes’ Upsets- are clipping or buckling of fibers cause d by crushing of fibers when the trunk is felle d violently over a rocky surface. Wind Cracks- are shakes on the outside of a lo g due to the shrinkage of the exterior surface cause d by the atmospheric influences.
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KNOTS Knots - are dark, hard pieces occurring as signs of branches broken or cut off.
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Shakes • Shakes- or cracks are caused by the rupture of tissues resulting in partial or complete separation of the fibers along the grain. Star Shakes Heart Shakes Cups Shakes Ring Shakes Radial Shakes
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BOW •
Bow- a curvature of the timber in the direction of its length. This defects are Due to Seasoning.
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CUPPING DEFECTS •
Cup- a curvature in the transverse direction of the timber. This defects also are Due to Seasoning.
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Wood TIMBER is the general name for wood materials.
There are 3 main types of timber:
• HARDWOOD • SOFTWOOD • MANUFACTURED BOARD AAERT _SCHOOL OF INTERIOR DESIGN
AAERT _SCHOOL OF INTERIOR DESIGN
Hardwood This type of timber is produced from broad leaf trees that lose their leaves in winter – a deciduous tree. The photograph opposite is of an oak tree which grows in this country. Uses - Oak is a hardwood and is used to make expensive furniture/flooring and strong framed structures.
The term hardwood does not mean that the timber is hard. For example balsa is used for modelling, it is a hard wood but it is one of the softest timbers to work with.
Model aircraft made from balsa
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Hardwood Mahogany – reddish in colour, always looks good when varnished or waxed.
Beech – creamy pinkish colour, its close grain makes it very suitable for kitchen utensils, as water does not have too great an effect on it.
Task – Can you think of other uses of wood products in the kitchen.
AAERT _SCHOOL OF INTERIOR DESIGN
AAERT _SCHOOL OF INTERIOR DESIGN
Softwood This type of timber is produced from trees that do not lose their leaves (coniferous). Softwood trees grow much quicker than the hardwood ones, they are therefore cheaper to buy and far more available. Softwood is used for construction of houses and furniture, and outdoor uses such as fencing.
Leaves are easily identified as being thin and narrow.
The term softwood does not mean that the timber is soft , as pitch pine is one of the most difficult timbers to work with, yet is a member of this group AAERT _SCHOOL OF INTERIOR DESIGN
Uses of soft woods Building
Furniture
Construction
Packaging
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Manufactured Products Of Timber These are manmade boards, which are made by gluing wood layers or wood fibers together. Examples of manufactured boards are:
Plywood is a widely used manufactured timber. Can you think of advantages and disadvantages of using plywood? The photograph opposite shows MDF sheets. What does MDF stand for ? Any thoughts regarding its use ?
Manufactured board is mainly used for kitchen and bedroom furniture and shelving. AAERT _SCHOOL OF INTERIOR DESIGN
Manufactured Products Of Timber • • • • • •
VENEERS LAMINATES PLYWOOD PARTICLE BOARD FIBER BOARDS BATTEN BOARDS : BLOCK BOARDS AND LAMINATED BOARDS
•
VENEERS - Thin sheet of wood, 0.4 mm to 0.6 mm in thickness obtained by different knife cutting process.
• PLYWOOD - is made by gluing together veneers. • It has a good strength both across as well as along the grain. • Plywood has better splitting resistance due to grains in adjacent layers running at the right angle and nailing and screwing even closed to the edges in safe. AAERT _SCHOOL OF INTERIOR DESIGN
Manufactured Products Of Timber • PLYWOOD • Can easily be bending to a curvature limited by the tensile and the compressive strength of the other plies. • The face piles made at different heartwoods show great aesthetic variety in grain pattern and color. • PARTICLE BOARDS - is a board manufactured from particles of wood or other cellulose materials. • BATTEN BOARD – it is a board having a core made up of strips of wood usually 8 cm wide each laid separately or glued or otherwise joined to form a slab. • BLOCK BOARD – these are boards having a core made up strips of wood each not exceeding 25 mm. AAERT _SCHOOL OF INTERIOR DESIGN
carve it…
you can …… layer it …
Bend it …..
turn it ….. slot it together it …..
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Things that attack timber
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Decay of Timber • Termites
• Beetles
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Timber Seasoning • Removal of moisture from timber so as to be in equilibrium with moisture in surrounding atmospheric conditions, where timber is likely to be used, is called as seasoning. • When timber is first felled it is known as green timber and has a very high moisture content – approx 50% • Before it can be used it must be dried • If this process is not controlled properly defects can occur that can ruin good timber • Aim of seasoning is to dry out the wood to a suitable moisture content of 22% or less
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OBJECTIVES OF SEASONING • Seasoning improves following properties: – Strength – Durability – Working qualities including polishing, painting, and gluing – Resistance to attack of insects, fungus • Proper seasoning reduces tendency to split, shrink and warp. • Seasoning reduces weight of timber and is easy to handle. • Timber becomes fit to receive preservative & to finish like preservatives, paints, and varnish treatment. • To reduce weight and minimize cost of transportation. • To make the timber burn readily, if used as a fuel.
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TYPES OF SEASONING • Natural Seasoning - is a slow process and the reduction in moisture content to the desired level may not be attainable by air seasoning alone. • Artificial or Kiln Seasoning - is a quicker method of seasoning timber t the desired moisture content under highly controlled conditions. • Electrical Seasoning - in this method high frequency alternate electric current is passed through timber. • Chemical Seasoning - If the outer layers of timbers are treated with such solutions, the vapor pressure of the outer layers is reduced and a vapor pressure gradient is set up.
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ADVANTAGES OF TIMBER • In terms of specific strength Timber can be used for both load bearing structures and non-load bearing instruments. • It can be easily converted to any shape and size. • With the advent of superior adhesives and other forms of timber connectors. • The wastage in timber construction is less because all wastes can be put one use or the other. • It has high resale and salvage value. • Timber has better insulating properties than any other materials. • Durability of timber can be very high, if properly seasoned and preserved. • Timber constructions are light in weight. • For aesthetic and decorative appearance.
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USES OF TIMBER AS A BUILDING MATERIAL • • • • • • • • • •
BEAMS TRUSSES RAFTERS JOISTS IN FLOORS DOORS FRAME AND SHUTTERS WINDOWS FRAME AND SHUTTERS STAIR CASES POLES PILES COLUMNS AAERT _SCHOOL OF INTERIOR DESIGN
Before we use wood, what should we think about ?
Wood - sustainability considerations. A tree absorbs CO2 as it grows and stores the carbon as wood. When it reaches maturity it stops absorbing extra carbon. Eventually, if not cutdown, it will die and gradually give off CO2 as it rots. If it is cut down and the wood is used for products such as furniture or buildings this
locks up the carbon in the timber for the lifetime of the product.
replaced the new tree will start absorbing more CO2. If the tree is
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Before we use wood, what should we think about?
Wood - sustainability considerations.
How does using wood affect Climate Change? If you use solid little processing.
Energy
timber there is very
is used to plant and then fell
move them, saw and plane the timber and then transport it. The further it is transported the more energy is used. the trees,
AAERT _SCHOOL OF INTERIOR DESIGN
Before we use wood, what should we think about?
Wood - sustainability considerations.
Manufactured boards use more energy to produce. They can use the waste from milling solid timber. They mostly use adhesives, and the formaldehyde that is used in MDF is a health risk.
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Before we use wood, what should we think about?
Wood - sustainability considerations. Other ecological impacts Some tropical hardwoods have huge impacts. Mahogany trees grow in amongst a variety of other trees and plants. Cutting down the mahogany causes the destruction of a whole area of rainforest which cannot regrow
Does easily. it’s use harm other people? If we add to Climate Change that affects everyone in the World but particularly the poor who are most affected by drought and flooding. If we destroy areas of rainforest that affects the lives of the people who live in the forest.
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Before we use wood, what should we think about?
Wood - sustainability considerations. Can we keep on using as much as we like? The planet has a limited amount of land to grow food and trees so there is a limit to the amount of timber we
can use. However, the amount that is used in the production of the paper that comes into the average house each year will be a far bigger impact than the timber in your school project. But the products we do design and
well made, so they can be used for a number of years. make should be
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OBTAINING NATURAL WOOD
HOW TO PROCESS WOOD
We can extract wood from a tree that is not too young or too old. The right age of cut depends on the species. To extract wood we follow these steps: Transport Cutting and pruning Removing the bark Sawing Dryin g
OBTAINING NATURAL WOOD
Step 1: CUTTING AND PRUNING.
The trees are cut in the winter, because they have less sap. The tools to cut trees used to be the AXE and the HAND SAW.
The tools used today are the CHAINSAW and big machines that cut the trunk quickly.
OBTAINING NATURAL WOOD
Step 2: TRANSPORTATION
From the beginning the trunks were transported by the rivers flow, or animals.
Today the trunks are transported by big lorries.
OBTAINING NATURAL WOOD
Step 3: REMOVING THE BARK This happens at the sawmill. A chain of rollers with metal teeth turns and removes the bark
OBTAINING NATURAL WOOD
Step 4: SAWING The trunks go to the sawmill. Here the worker marks the lines to cut the wood. This woodcutter makes planks, boards, beams, etc. The tools to cut the wood are: • traditionally circular saws, and • today big electrical machines.
OBTAINING NATURAL WOOD
Step 5: DRYING THE WOOD
The wood is dried so that it doesn’t wrap. Dry wood lasts longer and is lighter.
OBTAINING NATURAL WOOD
Step 6: PLANING The wood is planed to make tho wood smooth and evenly flat and give it a good finish