Materials

Wood

Softwood

Fast growing

Coniferous

Types

Redwood: Strong, used for constructional work, knotty.

Parana pine: hard, more expensive, straight grain, knot free, used for staircases, doors and built-in furniture.

Hardwood

Have broad leaves

Shed leaves each year

Slow growing

Mahogany: Straight grain, strong, used for furniture, musical instruments and watercraft exteriors.

Beech: Smooth texture, straight grain, strong, used for mallets

Oak: Straight grain, heavy and strong, used for constructing frames for buildings.

Elm: Grain interlocks, resists splitting and resists decay when wet, used for furniture, water troughs, barrels, boxes and crates.

Timber

Is either a hardwood or softwood

Defects:

Dry rot

Wet rot

Insect attack

Splits

Knots

Shrinkage

Manufactured board

Advantages

·        Available in large sizes and thickness

·        Not prone to defects

·        Can be used to improve appearance

·        Do not have a grain structure

·        More easily worked

·        Can easily be joined

Medium Density Fibreboard

Qualities:

·        Quality board

·        Cost effective

·        Smooth surface

·        Finishes well

Process:

·        Fine wood dust and resin pressed into board

Uses:

·        Building and furniture trades

Chipboard

Qualities:

·        Cheap but not strong

·        Veneered with a hardwood or plastic

Process:

·        Compressing wood particles together with glue

Uses:

·        Compressing wood particles together with glue

Plywood

Qualities:

·        Very strong

·        Appearance can be improved

Process:

·        Odd number of layers glued at 90-degree angle

Uses:

·        Building work,

·        General construction

·        Boat frames

·        Furniture making

Blockboard

Qualities:

·        Cheap substitute to plywood

Process:

·        Strips of softwood glued side by side sandwiched between 2 veneers

Uses:

·        Shelving

·        Worktops

·        Furniture backs

Hardboard

Qualities:

·        Not as strong as the other boards

Process:

·        Pulped wood fibres put under pressure until fibres bond.

Uses:

·        Pulped wood fibres put under pressure until fibres bond.

Metals

Ferrous (Contains iron)

Mild steel: Tough, High tensile strength, Rusts easily. Uses: School workshops, Car bodies, Nuts, bolts

Carbon steel: Tough, hardened + tempered if needed. Uses: Drill bits, hacksaw blades

Stainless steel: Tough, resistant to rust, expensive. Uses: Cutlery, Medical instruments, kettles, sinks.

Non-ferrous (No iron)

Aluminium: Ductile, Soft, Malleable, Polishes well, very light, Conducts heat + electricity well, corrosion resistant, expensive. Uses: Window frames, saucepans, cooking foil, aircrafts.

Copper: Ductile, malleable, conducts electricity and heat, expensive. Uses: Water pipes, wires, cisterns.

Brass: Hard, strong, Malleable, ductile, yellow in color, Corrosion resistant. Uses: Electrical parts, door handles, bathroom fittings, accessories.

Plastics

Thermoplastics

Types

Polythene (high density) HDPE: Strong, softens at 120-130C. Used for pipes, bowls, milk creates and buckets.

Polythene (low density) LDPE: Weaker, softer, more flexible. Softens at 85C. Used for packaging, film, carrier bags, toys, squeezy detergent bottles.

Polypropylene (PP): High impact strength, Softens 150C. Can be fixed many times. Used for Bottles, Crates, Boxes, Medical equipment, Food containers, Nets, Storage containers.

High impact Polystyrene: Light but strong, Available in sheets, softens at 95C. Used for vacuum forming, school projects.

Nylon (Polyamide): Hard material, Resists to wear and tear, low friction qualities, high melting point. Used for Curtain rail fittings, Combs, Hinges, Bearing, Clothes, Gear wheels.

Rigid PVC (Polyvinyl chloride): Stiff, hard wearing. Plasticiser added to soften. Used for Air and water pipes, Chemical tanks, Shoe soles, Shrink and blister packaging, Floor and wall coverings

Acrylic (Polymethyl-methacrylate) / Perspex: Opaque to glass-like transparency, can be coloured with pigments, hard wearing, shatters if treated roughly. Used for Display signs, Baths, Roof lights, Machine guards

Thermosetting

Melamine formaldehyde (Methanal, MF): Heat resistant. Used for Tableware, Electric installations, Synthetic resin paints, Decorative laminates, Worktops.

Epoxy resin (Epoxide, ER): Resin + hardener mix. Used for Castings, Printed circuit boards (PCBs), Surface coating, Araldite Glue ™

Polyester resin (PR): Resin + hardener, polymerises at room temperature. Used for lamination, reinforced plastic, castings, Encapsulations, Car bodies, Boats

Phenol formaldehyde / Phenol Methanol / Bakelite: Hard, brittle, Dark colour, glossy, Heat resistant. Used for dark coloured electrical fittings, parts, kettles, iron, saucepan handles.

Urea formaldehyde: Colourless polymer (uses artificial pigments). Used for door and cupboard handles, electrical switches, electrical fittings