Metals (incomplete)

Question 1

ferrous metals

Answer 1

metals containing iron, they are magnetic and degrade in the form of rust

Question 2

non-ferrous metals

Answer 2

metals that do not contain iron

Question 3

alloys

Answer 3

metals consisting of two or more different metals combined to improve their properties

Question 4

sheet metal (stock form)

Answer 4

large flat sections of metal with thickness < 3 mm

Question 5

Plate (stock form)

Answer 5

thick areas of metal generally > 3 mm

Question 6

Bar (stock form)

Answer 6

solid prisms of metal with a range of cross sections (e.g. round bar, flat bar ect)

Question 7

Tube (stock form)

Answer 7

hollow bar with a range of cross sections (e.g. square, hexagonal, round ect)

Question 8

structural angular (stock form)

Answer 8

shapes such as H, L and I beams, T bar and channel

Question 9

metal ore

Answer 9

impure metal locked inside other rocks and minerals that is purified and separated into pure metal

Question 10

chalcopyrite

Answer 10

Copper ore

Question 11

Bauxite

Answer 11

Aluminium ore

Question 12

Cassiterite

Answer 12

Tin ore

Question 13

Zinc blende

Answer 13

Zinc ore

Question 14

Work Hardening

Answer 14

cold working a material (such as bending or rolling) compresses and distorts the crystal structure of a metal preventing the crystals from moving which improves hardness but increases brittleness and cracking

Question 15

Case Hardening

Answer 15

used to harden steels with a less than 0.4 % carbon content
the metal is heated and carbon is allowed to impregnate the surface material making it harder high carbon steel on the surface but softer, less brittle low carbon steel in the core

Question 16

Annealing

Answer 16

hard metal is heat and then slowly cooled
this relaxes and expands the crystal structure and softens the material

Question 17

Quenching

Answer 17

hot metal is cooled very quickly in water, oil or salt water. This cools the metal without allowing the crystal structure to relax, keeping the outside of the material hard while maintaining a soft core

Question 18

Carburising

Answer 18

steel is placed in a ceramic box with carbon and heated to 930-950 C
carbon atoms impregnate the metals structure
the longer it is held at this temperature the more carbon that enters the material and the harder it gets
the metal is removed and heated to 750 degrees and quenched to seal the surface

Question 19

Hardening (general explanation)

Answer 19

the crystal structure of a metal is compressed and altered holding each crystal in place which prevents the material from bending easily or altering its shape and thus it is harder

Question 20

Tempering

Answer 20

metal is heated below a critical temperature and air cooled
this relaxes some of the crystal structure and removes some of the hardness

Question 21

Tempering colour

Answer 21

the colour a metal glows to indicate an amount of brittleness is removed

Question 22

Forming processes

Answer 22

materials are deformed into a new shape but no material is added or removed

Question 23

redistribution

Answer 23

melting and reforming a material into a new shape

Question 24

wastage

Answer 24

material is cut away until the material is the correct shape

Question 25

Press forming

Question 26

Spinning

Question 27

Cupping/deep drawing

Question 28

Drop forging

Question 29

Wrought iron forging

Answer 29

wrought iron bars (Carbon < 0.08%) are heated in a forge and forged using hammers or hydraulic presses in order to make complex shapes
suitable for batch or one off production

Question 30

Bending

Answer 30

Stock form: sheet or plate
Process: a punch is presses a sheet material into a angled die causing it to bend into the desired shape, does not punch or trim the metal
Uses: seams on metal edges, casing/ housing units

Question 31

Rolling

Question 32

Sand casting

Question 33

Gravity die casting

Answer 33

low melting point metals are poured into a open die where gravity causing the metal to fill the mould
less precise than pressure die casting but cheaper and easier to do

Question 34

Hot chamber pressure die casting

Question 35

Cold chamber pressure die casting

Question 36

Investment casting

Question 37

Low temperature Pewter casting

Question 38

MIG welding

Answer 38

Metal Inert Gas welding
a large potential difference builds up on the electrode and the work piece
and arc of current jumps the gap melting both the electrode and the small area of the work piece joining them together
an inert gas such as CO2 shields the join from oxidation
the electrode is constantly used up

Question 39

TIG welding

Question 40

Oxy-acetylene welding

Answer 40

a mixture of oxygen and acetylene (ethyne) are pumped out of a torch and ignited in a high temperature controlled flame which melts a filler rod into a join in the base metal creating a join

Question 41

Spot welding

Answer 41

sheet metal is held between two copper electrodes. an electrode discharges at a single point connecting the sheet together.
individual single points connect the sheet at many points along the length

Question 42

Soldering

Question 43

Brazing / Hard soldering

Question 44

Riveting/ Pop riveting

Question 45

Milling

Question 46

Turning

Question 47

Flame cutting

Question 48

Plasma cutting

Question 49

Laser cutting

Answer 49

A high power beam of light vaporises a single point on the material cutting through it. an inert gas such as CO2 clears away the cut material preventing it from reforming.