prepared by: ar. joshima v.m., university of nizwa · pdf filein design concept brings...
TRANSCRIPT
Prepared by: Ar. Joshima V.M., University of Nizwa
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1. WOODEN 2. BAMBOO 3. WICKER
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1. METAL 2. CONCRETE
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1. PLASTIC 2. STONE 3. GLASS
Wood and Wood Products
Metals and Alloys
Glass
Plastics
Upholstery
Miscellaneous
Furniture making materials
Furniture designers need to know about materials:
Choose appropriate material in a given situation
Materials decide the strength, comfort and aesthetics of the furniture.
Thinking about the abilities and inabilities of materials in design concept brings innovative design ideas.
Material research also focus on the environmental issues, health related issues, physical and performance issues.
Why study about materials?
1. Absorptive quality
2. Compressive and tensile strength
3. Density
4. Dimensional change
5. Ductility
6. Elasticity
7. Stability
8. Surface quality
9. VOC content
10. Workability
Material Properties
Absorptive quality: ability of the material to absorb moisture, oils and odors.
Eg 1: When we consider different types of wood.
Mahogany has good absorptive property and can be stained/colored better.
Hard maple has less absorptive property and require more difficult process to stain.
Teak wood has high natural oil content and can be finished using shellac.
Cork will stain but does not absorb moisture.
Eg 2: Stones
Granite is igneous rock and does not absorb moisture or odors.
Marble will absorb moisture and oils and will stain with olive oils and acids.
Eg 3: Fabric/Textiles
Fabric and textile will absorb moisture, oils and odors.
Material Properties
Compressive and Tensile strength:
Compressive strength is the ability of the material to resist compressive forces (pushing).
Tensile strength is the ability of the material to resist tensile forces (pulling)
Eg: Wood is strong (compression and tension) in the direction of the grain, but when pulled at right angle to the grain it will split. Wood is also weak in shear force, making it relatively easy to split with an axe or chisel.
Steel is excellent in both tension and compression. Hence mostly used for structural frameworks.
Material Properties
Density: measure of the cellular structure of a material relative to its volume.
Denser materials conducts(take) heat away from body at a faster rate, giving a sensation of coolness to the touch.
Which one is cool to touch?? Concrete or Steel or Wood??
Material Properties
Dimensional Change: is the shrinkage or expansion of materials due to changes in environmental conditions.
Eg: wood can absorb moisture and expand. The same wood can lose moisture and shrink.
Different varieties of wood have different rates of dimensional changes.
Eg: metal can get lose or tight on the joints depending upon the environmental temperature.
Dimensional change becomes important when two or more materials need to be combined in one joint. Tolerances need to be given to allow for relative changes of materials.
Material Properties
Ductility: ability of material to be molded or shaped without breaking.
Eg: copper is more ductile than aluminum. Copper can be hammered or formed but aluminum can only be casted, extruded or rolled.
Elasticity: ability of material to completely recover from the deformation after the load is removed.
Eg: rubber when load is applied deforms and recovers completely after load is removed.
Material Properties
Stability: ability of material to have little or no dimensional change when moisture, temperature or force changes.
Eg: MDF is a stable wood composite material. Ceramic, granite, stone and thermosetting plastics are also very stable materials.
Lack of stability is the reason why long shelves or beds sag after a long time of use.
Surface Quality: describes the visual and tactile qualities of a material’s surface.
Visual qualities of finished wood surfaces is depth and luster. Depth gives a feel of deep stains and luster is the ability of wood surface to reflect light.
Visual quality of unfinished wood is grain and texture. Grain is the direction of the fibers and texture is the feel of the wood surface as fine or course.
Material Properties
VOC: Volatile organic compounds are compounds that become vapor when open to air. VOC cause lot of health problems and environmental problems.
Eg: adhesives/glues emit VOC, Some paints emit VOC. Which delays the use of finished products and require off-site storage to allow vapourization.
Workability: materials response to being cut, drilled, sanded, planed, folded or shaped. Determines how easy a material can be worked with to make variety of shapes and sizes.
Eg: wood is highly workable and can be cut, sanded etc.
Marble is a fragile material that can break easily when made into thin section.
Material Properties
Materials respond to changes in the environment.
Knowledge about material properties will help the designer to predict how the furniture respond to environmental conditions.
Material properties influence the performance of furniture.
Material properties contribute to the form and function of furniture.
Material Properties
• Wood has a pleasing appearance with its color,
texture and grain pattern. • Is warm to the touch, and is durable. • Wood is strong and stiff. • Easily worked with a wide variety of tools
(machine or hand) to make artistic and functional shapes.
• Easier to join to other pieces of wood or other materials.
• Can be readily finished with varnishes, paints, and similar materials to enhance its natural appearance.
• Locally available and a renewable resource.
Wood
1. Solid wood
• Solid wood has been furniture making material from recorded time.
• Solid wood used for furniture can be from hard wood or soft wood.
• Best quality wood is used for exposed furniture making and lesser quality wood is used for hidden frames, cabinet backs etc.
• Now it is unfeasible to mass-produce solid wood furniture.
Wood and Wood Products
Hardwood Softwood
Definition Comes from deciduous trees that has slow growth rate.
Comes from coniferous trees which grow faster.
Examples
mahogany, teak, walnut, oak, ash, elm, aspen, poplar, birch, maple etc.
pine, spruce, cedar, fir, larch, douglas-fir etc.
Cost more expensive than softwood less expensive compared to hardwood.
Density Hardwood has a higher density and is therefore usually harder.
Softwood has a lower density, therefore most softwood varieties are softer than hardwood.
Color Dark Light
Strength Strong in compression, tension and shear(strong along and across the grains)
Strong in tension but weak in shear(strong along the grains)
Grain structure
Non - resinous and close grained Resinous and splits easy
Fire resistance
High Poor
2. Veneers
• Veneers are thin layers of real wood that are sawn, peeled, or sliced to a variety of commercial standard sizes.
• Veneers can be glued to other materials like MDF, Plywood or cheaper quality of wood under pressure, to improve the appearance.
• Veneers are light in weight and can be bent in desired forms.
• Any wood finishes are possible in veneers.
Wood based materials
More expensive with higher-
quality production.
Durable, but delicate and can scratch easily.
3. Plywood • Plywood panels are made from thin sheets
of wood veneer. • It is one of the most widely used wood
products. • It is flexible, inexpensive, workable, re-
usable, and can usually be locally manufactured.
• Plywood is used instead of plain wood because of its resistance to cracking, shrinkage, splitting, and twisting/warping, and its high degree of strength.
Wood based materials
• Plywood layers are glued together with adjacent layers
with their grain at right angles to each other.
• Cross-graining reduces the tendency of wood to split when nailed at the edges and reduces expansion and shrinkage and makes the strength of the panel consistent across both directions.
• There are usually an odd number of plies so that the sheet is balanced and reduces warping.
• Plywood is available in variety of sizes.
4. MDF (Medium Density Fiberboard) • Made out of wood fibers glued together under heat
and pressure. • Affordable and often durable as solid wood. • It can be drilled, cut or nailed together without
damaging the surface. • MDF boards are available in different thicknesses. • It can be covered with wood veneers or laminates
and can be painted. • Since these are made of wood fibers, they have a
very poor screw holding capacity.
Wood based materials
5. Wood Laminates:
• Laminates are made of products like paper, which is applied over a wood frame and sealed with a protective layer of thermosetting resin.
• They are used to cover a variety of furniture for heavy use due to its durability.
• Unlike real wood or veneers, laminates will not fade or have variations from piece to piece.
• They are also very easy to clean.
• Available in more styles and colors to choose from
Wood is available in boards or sheets of limited sizes.
Joining of wood pieces become important for any applications.
Joinery describes the variety of wood joints that are used in making furniture, paneling doors and manufacturing windows and other items.
Wood joints deals with shrinking and swelling of wood, warping, end grain appearance and problems of gluing.
Dimensional change is one important factor to consider while designing wood joints. It should always have space for tolerance.
Wood joinery
Types of
wood joints
A Simple butt joint is a joinery technique in which
two members are joined by simply butting them together.
End grain is butted to long grain gluing surface and the resulting joint is mostly weak.
Mostly used for making frames.
Dowelled Butt-joint
Biscuit Butt-joint
Screwed Butt-joint
Pocket hole screwed Butt-joint
Tongue and groove joints allow two flat pieces to be joined strongly together to make a single flat surface.
Used mainly with wood, for flooring, paneling, parquetry etc.
Half Lap joints can be used in wood,
plastic, or metal in joining two pieces of material together by overlapping them.
Used for frame assembly in cabinet making.
A scarf joint is a method of
joining two members end to end in woodworking or metalworking.
The scarf joint is used when the material being joined is not available in the length required.
A miter joint is made by beveling each of two parts
to be joined, usually at a 45° angle, to form a corner, usually a 90° angle.
A disadvantage of a miter joint is its weakness, but it can be strengthened with a spline.
Used for making frames and boxes.
The mortise and tenon joint is to join pieces
of wood, mainly when the adjoining pieces connect at an angle of 90°.
In its basic form it is both simple and strong.
A finger joint or comb joint is made
by cutting a set of matching rectangular cuts in two pieces of wood, which are then glued.
The finger joint is the most common joint used to form long pieces of lumber from solid boards.
The finger joint can be used when fixing tables and chairs, and also in floor boards, timber roof and door construction.
A dovetail joint is a commonly
used woodworking joinery.
Noted for its resistance to being pulled apart.
The dovetail joint is commonly used to join the sides of a drawer to the front.
Wood finishing starts with Sanding either by
hand, or power sander, scraping, or planing.
Imperfections or nail holes or pores may be filled using wood filler.
Often, the wood's color is changed by staining or bleaching.
Finishing on wood Sanding by hand
Power Sanding
Planing
Wood filling
Wood staining
Once the wood surface is prepared and stained, the finish is applied.
It usually consists of several coats of varnish /lacquer (any type) and each coat is followed by sanding.
Lacquer sheen is a measurement of the shine for a given lacquer. Eg: flat, satin, egg shell, matte, gloss, semi-gloss and high-gloss.
A final coat of wax is applied over the finish to add a degree of protection.
Finishing on wood
