AQA A level design and technology

compressive strength

the force at which a material breaks under pressure

tensile strength

A measure of how much stress from pulling, or tension, a material can withstand before breaking.

bending strength

The ability to resist forces that may bend the material.

shear strength

measures the largest shear force a materials can stand before ripping apart

Torsional strength

Resists a twisting force

Hardness

A measure of how easily a mineral can be scratched

Toughness

the ability of a material to resist fracture

Plasticity

ability to be molded

Ductility

The ability to be pulled into thin wires

Malleability

the ability of a solid to be hammered without shattering

Elasticity

The ability of a material to bounce back after being disturbed

Density

the degree of compactness of a substance.

Fusibility

Ability to become a liquid when heated

Magnetism

The force of attraction or repulsion of magnetic materials

electrical conductor

A material through which electric charge can flow easily

electrical insulator

a material through which charge cannot flow easily

thermal conductor

a material through which thermal energy flows easily

thermal insulator

a material through which thermal energy moves slowly

thermal expansion

the expansion of matter when it is heated

opaque

impossible to see through; preventing the passage of light

translucent

Allowing light to pass through

transparent

Allowing light to pass through

Ferrous

with iron

Non-ferrous

containing no iron

Alloys

mixtures of two or more metals

Thermoplastic

a material that softens when heated and hardens again when cooled

Thermosetting

Capable of being permanently hardened by heat and pressure; resistant to the further effects of heat.

Elastomer

a natural or synthetic polymer having elastic properties

composite

made up of separate parts

Smart materials

Materials which change in response to their surroundings, such as light levels or temperature.

Modern materials

Materials that are developed through the invention of new or improved processes.

toughness test

Izod impact test-Tough materials absorb impact, brittle materials shatter

Paper stock forms

sizes from A0 (largest size) to A8 (smallest), each 'A' size is half the size of the previous one - for example, A4 is half the size of A3.

compliant materials

materials that are flexible, such as textiles and some plastics

gsm

grams per square meter

Rough Sawn

Timber direct from the saw.

Planned square edge (PSE)

wood has only one edge that is planned accurately, the rest is rough sawn

Planned all round (PAR)

wood has sides and edges that are all planned square, straight and level

natural wood

wood that comes from trees and is available only at the maximum width of the tree

Manufactured boards

Made from converting logs into a variety of forms and gluing them together to create sheet materials.

mouldings

Pre-made moulding's such as skirting boards or wooden trims are readily available in standard lengths up to approximately 4 metres.

Air seasoning

a traditional inexpensive method which involves stacking the wood under a shelter, protected from the rain. Air circulates between the planks to slowly remove the excess moisture

kiln seasoning

more expensive but controlled method which is very quick and can take just a few weeks. Planks are stacked onto trolleys and placed in the kiln where both temperature and humidity are controlled

Bauxite

A mineral used in making aluminum

synthetic polymers

man made polymers made from crude oil

Natural bio-polymers

made from natural materials

Synthetic bio-polymers

made from renewable resources but chemically engineered to break down more quickly

Shape memory alloys

Shape memory alloys are metals that when deformed, can spring back into its original shape once released.

Thermochromic pigments

Pigments that change colour in response to heat (smart material)

Phosphorescent pigments

Pigments that absorb light and then re-emit it over time (smart material)

Photochromic pigments

A smart material which changes colour in response to a change in light e.g. sunglasses which tint in sunlight

Electroluminescent wire

Thin copper wire coated in a phosphorescent material that glows in response to an alternating current

Piezoelectric

the generation of a voltage across a solid when a mechanical stress is applied

antistatics

Reduce the likelihood of the polymer building up a static charge.

Thermal antioxidants

Prevent the polymer oxidising or discolouring due to excessive heat during processing.

lubricants

materials that reduce friction

flame retardant

a substance that is applied to material to make it resistant to catching fire

plasticisers

to make polymers soft and flexible e.g. plasticised PVC.

Bio-batch additives

help reduce the degradation time using oxy-degradable, photo-degradable and hydro-degradable additives

Antioxidants

Organic molecules that help protect the body from harmful chemicals called free radicals

preservatives

additive used to protect against decay, discoloration, or spoilage

Work hardening

Also known as strain hardening or cold working, this is the process of toughening a metal through plastic deformation.

Annealing

heat (metal or glass) and allow it to cool slowly, in order to remove internal stresses and toughen it.

case hardening

Hardening of the outer surface (or case) of a steel component; used to improve wear and fatigue resistance.

carburising

The addition of carbon to the surface of a low-carbon steel to improve hardness and strength.

Quenching

Cooling a hot piece of metal rapidly, as in water or oil.

die cutting

the process by which a part is cut from a piece of cardboard or paper using a steel die

Cutting Dies

Die cutters are used to cut out 'nets' or 'developments' that, when folded and assembled, will form a 3D shape such as a box

Creasing rules

Creases are created in paper or card using a blunt creasing cutter to make crease areas for folding edges

Vacuum Forming

lightweight trays, box inserts and liners

thermo-forming

bath, food packaging

calendering

thin polymer sheet or film

line bending

acrylic boxes, shelves

Lamination

boat hulls, train carriages, film props

injection moulding

electrical products casings

blow moulding

drink bottles, shampoo bottles, detergent bottles

rotational moulding

traffic cones, kayaks, water tanks

extrusion

solid rods, tubing, angular sections

compression moulding

electrical light fittings, picnic plates and cups

Forming

no material is removed, but materials are deformed to produce the required shape

Redistribution

the material is changed from one form to another without loss of material

wastage

processes that cut away material to leave the desired shape.

Press forming

metal seats, car body panels, boxes and containers

spinning

saucepans, metal light shades, body of stainless steel kettles

cupping and deep drawing

fire extinguishers, aerosol cans, drink cans

drop forging

spanners, pliers and screwdrivers shafts

wrought iron forging

decorative metalwork

sand casting

railway carriage wheels, wood working clamps, vices, drain covers

gravity die casting

alloy wheels, engine components, door knobs and handles

Pressure die casting (hot chamber)

toy cars, decorative door knobs and handles

Pressure die casting (cold chamber)

toy cars, decorative door knobs and handles

investing casting (lost wax casting)

cast jewellery, hip replacement joints

low temperature pewter casting

jewellery key fobs and decorative components

MIG Welding

Metal Inert Gas

TIG Welding

tungsten inert gas welding or gas tungsten arc welding

Oxy-acetylene welding

Uses a mixture of Oxygen and Acetylene to create a flame that will burn at temperatures of around 2500°C.

spot welding

used to join two pieces of sheet metal by passing a high electrical current through a small spot where the two pieces touch.

Soldering

Joining small pieces of metal together using molten metal.

Brazing

the process of joining metal with a filler rod that melts at a temperature below the metal being joined

self-tapping screws

screwed in through a pilot hole to cut its own thread