3.1 Types Of Materials Flashcards
(23 cards)
Physical Properties:
Mechanical
How a material will reach to physical forces (eg. Brittle when repeatedly bent)
Electrical:
A material’s conductive properties including insulation and resistance. Eg. A screwdriver’s polymer handle (insulator) protects the user from electric shocks through the tip (conductor)
Chemical:
How a material reacts to other chemicals eg. Metals oxidising
Thermal:
How a material responds at different temperatures eg freezing and boiling points. Such as the temperature ranges where thermoplastics can be shaped
Magnetic:
Most ferrous materials are attracted to magnets or can be magnetised. Such as the use of magnetic catches for doors
Permeability
The degree to which liquids or gases can pass through a material. Eg varnished wood has low permeability to liquids and water resistance
Aesthetic
The visual properties of the surface of a material. Such as colour and shine.
Tactile
The touch or sensory properties of a material, such as texture
WORKING PROPERTIES
Strength:
The ability to withstand a constant external force without failing
Hardness
The ability to resist wear and tear (scratching and dents) - usually related to surfaces
Toughness
The ability to withstand blows or momentary shocks
Durability
The ability to resist wear such as weathering
Elasticity
The ability to bend and then to return to its original shape
Plasticity
The ability to. Permanently change shape or form which allows to materials other than polymers
Malleability
The ability to permanently change shape, in all directions, while retaining integrity.
Ductility
The ability to change shape by stretching along its length without snapping
What to do when selecting materials?
Important to get spec right
Essential to identify the requirements for the user
Functions or conditions that the product will be exposed to
Once a design spec has been drafted - the physical and working properties can be identified.
KEY TERMS
Force:
A power that produces strain on a material and that can potentially change its shape 5 forces: COMPRESSION TENSION TORSION SHEER BENDING
Physical property:
An observable or measurable characteristic of a material (strength or density)
Prototype
A working model in the early stages in development
Used to help refine the product before beginning final or large scale production
Stiffness
Resistant to forces of bending or torsion
Stress or strain
A force created by pressure on an object or material. That has the potential to damage it by changing its shape.
Working property
The way a material behaves when being worked or shaped or whilst being used within a product
