GCSE DT: General

What is a ferrous metal?

A metal that contains iron

What are some examples of ferrous metals?

cats iron, mild steel, stainless steel

Properties of ferrous metals?

melting point of 1600 degrees or higher, prone to rusting and corrosion(apart from stainless steel)

Cast iron uses and properties?

cookware, good hardness and compressive strength, poor tensile strength

Mild steel uses and properties?

nuts and bolts, cheap and easy to machine, prone to corrosion

Stainless steel uses and properties?

an alloy of steel containing chromium, kitchen equipment, tough, strong, hard and corrosion resistant, difficult to machine

What is a non ferrous metal?

a metal that doesn't contain iron

What are some examples of non ferrous metals?

-aluminium

-copper

-tin

Properties of non ferrous metals.

-good corrosion resistance but can tarnish

-non magnetic, so can be separated from ferrous metals

Aluminium properties and uses?

-drink cans

-lighter than steel, but not as strong

Copper properties and uses?

-electrical wiring

-good conductor of heat and electricity

Tin properties and uses?

-coating steel cans for corrosion resistance

- soft and malleable

-good corrosion resistance to water

What is an alloy?

a mixture of two or more metals that has better properties that the pure metal

What are some examples of alloys?

-brass

-pewter

-solder

Brass properties and uses?

-made of copper and zinc

-musical instruments

-low friction, corrosion resistant and malleable

Pewter properties and uses?

-made of tin copper and antimony

-jewellery

-low melting point and easy to cast

Solder properties and uses?

-made of tin and lead

-attaching electrical components to circuit boards

-good electrical conductivity, low melting point and reasonable strength

What is polishing?

when you cut the surface of the metal until it's smooth

What's dip coating?

blow air through the powder to make it act like a liquid, then you dip metal in and heat it for a smooth finish

What's powder coating?

when the powder is sprayed onto the metal

What's adonising?

electrolysis and addition of colour that can give a corrosion resistant finish to aluminium

What is plating?

uses electrolysis to create a corrosion resistant layer(chrome plating)

What is galvanising?

when the metal is dipped in a bath of molten zinc

What is shearing?

cutting process that is used to separate pieces of sheet metal

What is welding?

melts edges of metal to join them together

What is brazing?

melting a filler metal to join the pieces of metal together

What is casting?

pour molten metal into a mould where is cools (die casting uses a reusable mould)

What is pressing?

the application of pressure to bend, form and stamp out holes from a metal

What is CNC milling?

rotating tool to make flats or grooves in metals

What are CNC metal lathes?

used to turn round parts

What is a smart material?

A material whose physical properties can change in response to an external stimulus

Hydro chromic ink.

-changes colour with water

-e.g. in charging socket of Iphone

Thermochromic pigment.

changes colour with heat e.g. on mugs

Photochromic dye.

changes colour with light e.g. glasses

Shape-memory alloy.

-changes shape with heat but can return to original shape

Polymorph.

thermoplastic used for prototyping as it can be reheated and remoulded many times

Phosphorescent material.

absorbs daylight and releases it in the night - glows in the dark

What is a composite?

combines the properties of two or more materials

Quantum tunnelling composite.

soft electrical switch that allows electrical current to flow when compressed

What is a modern material?

technical materials that have been manufactured for a function

Graphene properties?

-stronger than steel

-flexible

-conducts heat and electricity

-lattice carbon structure

-one atom thick = almost transparent

Titanium uses and properties?

-strong compared to weight and is anti-corrosive

-dental implants

Metal foams properties?

-string, lightweight, can conduct heat and electricity

-porous metal structures made from titanium and aluminium

-made by injecting gas into the liquid metal

Nanomaterials properties.

-between 1 and 100 nanometres

-include carbon nanotubes and fullerenes

-can be used to deliver medicine or coating in computer chips

Fibre optics.

-strand of pure glass designed to transmit signals by using pulses of light

-connects router to internet

Cornstarch polymers

-composite plastics which are biodegradable

Biopolymers.

-polymers produced by living organisms

-used for disposable cutlery

What are the types of motion?

-rotating#

-linear

-reciprocating

-oscillating

Rotating definition.

movement in a circle

Linear definition.

motion that goes straight in one direction

Oscillating definition.

swinging backwards and forwards

Reciprocating definition.

motion is backwards and forwards

What is a lever?

a simple form of machine that change the amount of effort or force needed to move a load

First class lever.

effort, fulcrum, load

fulcrum in middle

Second class lever.

effort, load, fulcrum

load in middle

Third class lever.

fulcrum, effort, load

effort in middle

What is a linkage?

linkages transfer motion between two positions

What are the types of linkages?

push-pull

tongs

moving wings

Push pull linkage.

reverses linear motion

Tongs linkage.

extends oscillating motion

Moving wings linkage.

reciprocating motion to oscillatin gmotion

What is a cam?

-follower moves up and down as cam rotates

-convert rotary motion to reciprocating motion

What is a pulley?

a pair of grooved wheels with a belt running in the groove

-they transfer rotary motion

-the smaller the radius, the higher the speed

What is a gear?

have teeth that mesh together that can change the speed or force of the motion they transfer

What are the types of gears?

-spur gear

-bevel gear

-worm and worm wheel

-rack and pinion

What does a spur gear do?

transfer rotary motion

What does a bevel gear do?

-changes rotary motion through 90 degrees

What does a worm and worm and worm wheel do?

-changes rotary motion through 90 degrees

What does a rack and pinion do?

changes rotary motion to linear

What is an electronic system?

system made up of input, process and output stages

What is an input device?

takes a real life signal and converts it into an electrical signal e.g. sensors

What is an output device?

take an electronic signal and turns it into a real world signal

e.g. speakers

What does a process do?

alters the electronic signal to create functions such as timing and counting

What does a system block diagram do?

-represents electronic systems

-arrows represent signals

-blocks represent the components that alter the signals

What are the input components?

-push to make switch

-tilt switch

-light dependant resistor(LDR)

-infrared sensor

What are the output components?

-light emitting diode(LED)

-buzzer

-speaker

-motor

What is a programmable component?

electric components that can be programmed to perform different functions

What is a microcontroller?

a small computer on a single integrated circuit that has ports for the connection of input and output devices

What is a driver circuit?

circuit used to control another circuit or component

e.g. if the current in an output device is too high

How are programmable components programmed?

-flowchart software

-block based editors

-raw program code

What are the pros of programmable components?

-can be reprogrammed many times = flexible

-can support a wide range of different input output devices

-reduce size of circuits because one programmable component can replace many integrated circuits

What are the cons of programmable components?

-need access to suitable programming software

-some programmable components can be expensive

What is an integrated circuit?

a complete electronic circuit contained on a single small microchip

What is a textile?

a general term used to describe any product that is made from a fabric

What is a fabric?

individual fibres that are spun into yarn and then knitted, woven or use a non-woven method to construct them

What are knitted fabrics?

made from yarns in a series of interlocking loops

-these loops can be arranged in different ways - weft or warp

What is weft-knitted fabric?

the loops area made in a horizontal way from a single warn and each consecutive rows of loop build upon the prior loops

What is warp-knitted fabric?

made with many parallel yarns that are looped vertically at the same time

How is a woven fabric strong?

the warp and weft(over and under) construction of the fibres reinforces the fabric

What is a selvedge?

an edge of the fabric that will not fray

What is a natural fibre?

fibres that come form animals or plants

Examples of natural fibres.

-cotton - plant bases

-wool - animal based

-silk - animal based

Cotton uses and properties?

-cellulose fibre from ripened seeds of the cotton plant

-strong, durable, absorbent but creases easily

-clothes

How is cotton harvested?

1. harvested from cotton plants

2. fibres are cleaned

3. carded between wire brushes to lie in same direction

4. spun into yarn

Wool uses and properties.

-an animal fibre from the fleeces of sheep

-warm, soft, absorbent and crease resistant

-jumpers

How is wool harvested?

1. fleece sheared from sheep

2. staple fibres are cleaned

3. then corded and spun into yarn

Silk properties and uses?

-an animal fibre from the cocoon of the silk moth

-smooth, lustrous and strong

-dresses

What are synthetic fibres?

human-made fibres, typically from oil

What are some examples of synthetic fibres?

-nylon -oil bases

-polyester - oil based

-acrylic - oil based

-viscose - regenerated

Nylon properties and uses.

-produced from two different chemical monomers

-strong, durable, warm, crease resistant

-sportswear