Please enable JavaScript.
Coggle requires JavaScript to display documents.
DT Materials - Coggle Diagram
DT Materials
Materials and their Applications
As a designer it is important to know how materials perform. Selecting materials is often a compromise of performance, cost and availability
Mechanical Properties -
Concerned with how a material reacts to an external force
Physical Properties -
Properties related to the intrinsic makeup or structure of materials
Mechanical Properties
Compressive strength -
The ability to withstand being crushed or shortened by pushing forces
Tensile strength -
The ability to resist being stretched by pulling forces
Bending strength -
The ability to resist bending forces
Shearing strength -
The ability to resist parallel sliding forces
Torsional strength -
The ability to withstand twisting forces
Hardness -
The ability to withstand abrasive wear
Toughness -
The ability to withstand impact
Plasticity -
The ability to be deformed and retain the deformed shape
Ductility -
The ability to be drawn out under tension without cracking
Malleability -
The ability to be compressed under pressure without cracking
Elasticity -
The ability to be deformed and then return to shape one the deforming force is removed
Physical Properties
Electrical/Thermal insulator -
Prevents the flow of current or heat
Thermal expansion -
The increase in the volume of a material with the application of heat
Electrical/Thermal conductor -
Allows the flow of current or heat
Degradation resistance -
the ability to withstand weathering and other environmental forms of wear
Opacity -
Prevents light transmission
Magnetism -
Attractive to iron or steels
Translucence -
Allows diffuse light through
Fusibility -
The ability of a material to be converted from a solid to liquid state, usually be heat
Transparency -
Allows light through
Density -
The mass of a material in a standard volume
Do's and Don't
Do's -
When answering questions about the physical or mechanical properties of materials, or the products that they are made in to, use the correct terms and justify the decisionWhen answering questions about the physical or mechanical properties of materials, or the products that they are made in to, use the correct terms and justify the decision
Eg Acrylic is used for the lenses of car headlights due to its plasticity and transparency, meaning that it can be moulded into complex shapes and remains optically clear
Acrylic is used for the lenses of car headlights due to its plasticity and transparency, meaning that it can be moulded into complex shapes and remains optically clear
Don't -
Don’t make unjustified statements using non technical vocabulary such as ‘It is a strong material’, or ‘it is a light material’
Avoid referring to a material as ‘cheap’, far too many variables, far too vague
Avoid hideous phrases such as ‘aesthetically pleasing’ or ‘environmentally friendly’
QUICK TEST
1.
Define what is meant by ‘Mechanical property’
2.
Define what is meant by ‘Physical property’
3.
Name and define 3 types of mechanical strength properties
4.
Give three material properties and justify their requirement, for a polymer used to create a single use drinks bottle
5.
Explain why a drill bit needs to be made from a hard material
6.
What classification of material is Beech?
7.
What are the 3 classifications for metals?
8.
Silicone is an example of a material from what classification?
9.
What is the meaning of ‘Compliant material’, what classification does it refer to?
10.
Define ‘Smart Material’ and name 2 examples
Classification of Materials
You will need to know the definition of each classification and be able to name specific materials in each class
Composites -
Particle based, fibre based and sheet based
Polymers -
Thermoforming, thermosetting and elastomers
Metal -
Ferrous, non-ferrous and alloys
Wood -
Hard wood, Soft wood and man-made boards
Materials are split in to a number of classifications, initially metals, woods, polymers, papers & boards, composites, smart materials and modern materials
These classifications can be further subdivided based on composition or properties
Wood
Hardwood -
Wood from broad leaved deciduous trees that lose their leaves in Autumn. They are generally slow growing
e.g. Oak, Beech, Ash,Birch, Teak, Mahogany
Softwood -
Wood from coniferous (cone bearing trees) They tend to be fast growing and evergreen
e.g. Pine, spruce, Douglas Fir, Cedar, Redwood, Larch
Man-made boards -
A man-made wood based composite board. Available in large sheet sizes
e.g. Plywood, Marine Ply, Aeroply, MDF, Chipboard
Metals
Ferrous -
A metal containing iron (Fe) or Iron and carbon. Ferrous metals rust and can be magnetised
e.g. low carbon steel (mild steel), medium carbon steel, high carbon steel
Non-ferrous -
A metal that contains no Iron. They do not rust and cannot be magnetised
e.g. Aluminium, Copper, Zinc, Silver, Gold, Titanium, Tin
Alloys -
A combination of two or more metals which delivers enhanced properties. They can be ferrous or non-ferrous
e.g. Ferrous - Stainless steel, Tool steel
Non ferrous - Brass, Bronze, Duralumin, Pewter
Polymers
Thermoforming or thermoplastic -
A material that can be repeatedly reheated and reformed allowing it to be recycled. A thermofoming polymer has long chain molecules
e.g. LDPE, HDPE, PP, HIPS, ABS, PMMA, PET, PVC
Thermosetting -
A material that when heated undergoes a chemical change where molecular cross bonds are formed leading to a material that cannot be recycled or reheated or reshaped
e.g. Urea Formaldehyde, Phenol Formaldehyde, Polyester resin, Epoxy Resin, Melamine Formaldehyde
Elastomers -
A material that at room temperature can be deformed under pressure and returns to its initial shape once pressure is removed. These polymers have weak bonds
e.g. Natural rubber, Silicone, Neoprene, Polybutadine
Composites
Sheet based -
e.g. Glulam, Aluminium composite board, (Plywood)
Particle based -
Tungsten Carbide, Concrete
Fibre based -
e.g. GRP, CFRP, Reinforced concrete
Papers and boards
Compliant materials that can be easily cut, scored and folded
Layout paper, tracing paper, cartridge paper, duplex board, block board, corrugated board, mounting board, foil lined board, laminated board, metal effects card, moulded paper pulp
Smart Materials
A material whose physical properties can be changed by an external stimulus. The change is consistent and reverts once the stimulus is removed
Shape memory alloys, Thermochromic pigments, Photochromic pigments, Piezoelectric material
Modern materials
A material whose physical properties can be changed by an external stimulus. The change is consistent and reverts once the stimulus is removed
Shape memory alloys, Thermochromic pigments, Photochromic pigments, Piezoelectric material
Investigating and testing materials
Materials testing is used to determine the best material for a given product or component.
Ensuring tests are fair is important, factors such as…
Using the same size and thickness of samples
Testing in the same environment
Ensuring equipment and technique, including positions and forces are the same
Simple tests that can be carried out in the workshop
Paper and card sizes
Paper is available in a range of A sizes, commonly A4, A3 and A2 are used with A4 being half the size of A3 and so on
Thicknesses or ‘weights’ Paper and card are specified in grammes per square metre. Anything over 200gsm is termed card
Specific paper materials
Layout/tracing paper -
translucent, fine smooth surface
e.g. sketch designs, transferring images
Cartridge paper -
Opaque, Excellent surface for ink and pencil
e.g. print work, art work
Specific card materials
Duplex/Carton board -
Folds cleanly, Good print surface on one face
e.g. Food packing, Outer packaging for small products
Duplex/Carton board
Folds cleanly
Good print surface on one face
Food packaging
Outer packaging for small products
Corrugated card
Light but impact resistant
Good insulator
Can print on in block colour
Transit packaging
Eco-packaging
Internal supports in packaging
Block/solid white board
High quality surface for print or embossing
Rigid
High end packaging of perfumes, electronic goods etc
Foil lined board
Water proof
Insulated
Outer surface can be printed on
Easy to fold
Drinks cartons or similar food packaging
Metal effects card
Easy to texture by embossing/debossing
Easy to fold/manipulate
High end or luxury packaging
