Materials and their Properties

What is strength?

What is strength?

The ability of a materials to withstand a force or load that is applied to it.

What are some forces that could be applied to a material?

• Tension

• Compression

• Torsion

• Bending

• Shear (like the action a scissors)

What is elasticity?

The ability of a material to return to its original shape when a force on it is removed.

What is ductility?

The amount that a material can be permanently stretched or deformed when a force is applied.

What is malleability?

The ability of a material for its shape to be permanently changed without breaking

What is hardness?

The ability of a material to resist wear or being scratched.

What is toughness?

The ability of a material to not break when a force is applied to it suddenly. AKA impact resistance.

What is thermal conductivity?

The ability of a material to allow heat to pass through it.

What is absorbency?

The ability of a material to draw in moisture

What is fusibility?

The ability of a material to be changed from a solid to a liquid by heat. E.g. interfacing

What are some different types of paper?

• Layout and tracing paper

  • Relatively hard and translucent

• Cartridge paper

  • Tough and lightly textured

• Grid paper

  • Printed squares and isometric grids

What are some types of boards?

• Corrugated cardboard

  • Fluted inner adds strength & low cost

• Duplex board (carton)

  • Tough, slightly textured & additives to prevent moisture/absorbance

• Foil-lined board

  • Aluminium foil laminated to one side

• Foam core board

  • Paper surfaces covering polystyrene core

What are some types of cards?

• Solid white board

  • Strong, high-quality and made from pure bleached wood pulp

• Inkjet card

  • Strong card, high quality forms are coated

What is the weight of standard printer paper?

80 gsm (grams per square meter)

How is paper/card made?

Cellulose fibres are derived from wood and grasses. Chemicals are added for texture and surface finish.

What happens to wood at the end of its usable life?

Can be burnt but if it ends up in landfill it’s biodegradable

What are some hardwoods?

• Oak

  • Strong and hard, open-grained, used in high quality furniture

• Mahogany

  • Fairly strong and durable, used in high quality furniture

• Balsa

  • Soft, off-white to tan colour, used in modelling

What are hardwoods?

Woods that come from deciduous trees and shed their leaves each autumn. They grow slower and have a closer grain

What are softwoods?

Woods that come from coniferous trees. They usually grow faster and have a more open grain.

What are some examples of softwoods?

• Pine

  • Strong and durable, easy to work with, used in construction and furniture

• Larch

  • Tough, water resistant, durable, used in boats and exterior cladding

• Spruce

  • Strong and hard, low resistance to decay, used in construction and wooden aircraft frames

What is wood seasoning?

When wood is dried before use to remove moisture, either in air or by gentle heating in a kiln. This makes the wood less likely to distort/warp.

How are manufactured boards made?

By gluing wood fibres or veneers together. These fibres can be waste materials from the cutting of natural timber.

Why are the properties of manufactured boards usually uniform?

There’s no grain.

What could be used as the top layer of a manufactured board?

A veneer from a high-quality wood for aesthetic purposes or a plastic laminate for protection.

What are some manufactured boards?

• Medium-density fibreboard (MDF)

  • Made from fine particle of timber mixed with bonding agent, used in furniture

• (Marine) Plywood

  • Made from layers of veneers or plies, used in furniture and boat building

• Chipboard

  • Made from chips of timber mixed with a bonding agent, used in kitchens

What are some ferrous materials?

• Low-carbon steel

  • tough, low cost, prone to corrosion

• Cast iron

  • good hardness and compressive strength

• High-carbon steel

  • Very strong and hard

What are some non ferrous materials?

• Aluminium

  • lighter than steel, not as strong

• Copper

  • excellent conductor

• Tin

  • malleable, good corrosion resistance

• Zinc

  • hard and brittle, relatively low boiling point

What are some alloys?

• Brass

  • made of copper and zinc, corrosion resistant and malleable

• Stainless steel

  • iron and chromium, tough, strong and hard

• High-speed steel

  • iron with some carbon, tungsten and chromium, very hard, strong but brittle

What are some thermoforming polymers?

• PET, used for drinks bottles and food packaging

• HDPE, used in bowls and buckets

• PVC, used in packaging and chemical tanks

• HIPS, used in packaging

• PP, used in ropes and carpets

• PMMA, used in display signs and baths

What are some thermosetting polymers?

• Epoxy resin, used in PCBs and adhesives

• Polyester resin, used in car bodies and boats

• Urea formaldehyde, used in plug sockets

• Melamine formaldehyde, used in laminates for kitchen worktops

• Phenol formaldehyde, used in lab countertops

What are knitted fabrics made from?

Yarns in a series of interlocking loops.

How are woven fabrics constructed?

They’re constructed from interlaced yarns

What is a selvedge?

An edge that won’t fray

What are non-woven fabrics made from?

Entangled raw fibres

How are non-woven fabrics made?

By using chemicals to mat the fibres together, with heat to bond the fibres or by stitching the fibres in layers

What do natural fibres come from?

Animals fibres: wool, silk, angora, mohair, cashmere
Plant fibres: cotton, linen, jute, hemp

What are synthetic fibres made by?

People, typically from oil or chemicals

What are some examples of natural fibres?

• Cotton

  • From ripened seeds of cotton plants, strong, durable and used in denim

• Wool

  • Fibre from sheep, warm, soft, absorbent and used in carpets

• Silk

  • Fibre from cocoon of the silk moth, strong, lustrous and used in dresses

What are some examples of synthetic fibres?

• Polyamide (nylon)

  • From two different monomers, strong, durable, warm and used in sportswear

• Polyester

  • From coal and oil, strong, durable, elastic and used in sportswear

• Elastane (lycra)

  • From polyurethane chemical, high stretch, improves comfort and used in sportswear

What is a blended fibre? Give an example.

Uses a mixture of different types of fibre, E.g. polycotton which has the absorbency of cotton and the quick-drying properties of other fabrics

What are some stock forms of textiles?

Roll size, width, weight and ply

How can waste be minimised when cutting out patterns from textiles?

Consider the layout of the pattern

What are metal foams?

Made from metal containing gas-filled pores. Have the physical properties of a metal but are 75% to 95% lighter. Used in sound damping.

What are the properties of graphene?

Form of carbon and is just one atom thick. About 200 times stronger than steel. Conduct heat and electricity.

What are some uses of graphene?

Solar cells, touch panels and smart windows

What are nanomaterials? What do they do?

Materials made up of particles that are less than 100nm in size. Nanomaterial coatings for glass/fabrics can repel dirt or water giving self-cleaning properties

What are smart materials?

When a material has a property that changes in response to an external stimulus.

What do thermochromic pigments do?

Change colour in response to temperature

What do photochromic pigments do?

Change colour in response to light levels

What are composites?

Materials that combine the properties of two or more materials

What are some examples of composites?

• Glass-reinforced polyester and fibre glass, used in car body building and repair

• Carbon-reinforced polyester, used to make tent poles and high-performance bicycles

What are technical textiles?

Textiles manufactured for performance properties rather than visual appearance.

What are some examples of technical textiles?

• Kevlar in body armour to protect from injury

• Fire-resistant fabric used in clothing worn by firefighters

What are conductive fibres?

Allow circuits to be incorporated into fabrics. This can be used to make temperature controlled clothing or to integrate lights into emergency clothing.

What do microfibres incorporate?

Micro-encapsulation e.g. woven polyester with tiny capsules embedded into the fibre. Used for anti-bacterial medical fabrics.

What are the benefits of using standard components?

• Buy materials in bulk (purchasing e.o.s)

• Divide equipment cost across millions of parts

• Automate the process

• Use labour efficiently

• Ensure the consistency of products is maintained

What are types of standard components

• Clips

• Hinges

• Brackets

• nails

• Zips

• Buttons

• Velcro

How can timbers be finished?

• Painting using oil, water or solvent-based paints

• Varnishing

• Tanalising (using a pressure treatment to preserve wood)

How can textiles be finished?

• Block and screen printing

• Can be dyed by hand or by machine

• Stain-resistant finishes can also be applied

How can papers and boards be finished?

• Printing using screen or block printing

• Embossing (steel dies are used to press a shape into the material)

• Ultraviolet varnishing to apply a glossy coating