metals Flashcards
ducticity meaning
ability of a metal to be drawm into a wire
malleability
ability to be reshaped without cracking
hardness
ability to resist abrasive wear / indentation
- cant be scratched or cut
toughness
ability to withstand impact - / absorb energy
if a material is hard it is also……….
brittle and will snap easily
if a material is tough it is also…….
soft - how it absorbs energy
strength meaning
ability to withstand force without breaking / permanently deforming
metals can be categorised as either
- ferrous
- non - ferrous
ferrous meaning
has iron
non-ferrous meaning
no iron
what is ferrous also known as
iron and steel
why is iron not very useful
it is soft and ductile
what happens when you mix carbon and ferrous to make steel
properties improve
what happens when there is more carbon
metal becomes hard and less tough
what are the three welding methods
mig
tig
spot (resistance)
what does mig mean
metal inert gas
what is mig used for
weld fairly thin metals together and tubes and box sections
what is used to generate an electric arc in mig
heat
what can the inert gas be in mig
co2
argon
what does the inert gas create in mig
a shield around the area being joined to prevent oxidation
what is mig suitable for
one off production / higher volume production
what is mig used to make
- bike frames
- playground equipment
- steel framed furniture
- vehicle exhausts
what does tig mean
tungsten inert gas
what is tip used for
stainless steel and non-ferrous metals
what is an example of an non-ferrous metal
aluminium
what does the tig allow
greater control and more accurate, stronger welds can be made
what is the required skill level to use the tig
high level of skill and it is slow
what is the tig used to make
- aluminium / titanium bike frames
- stainless steel swimming pool ladders
what is spot welding and resistance welding used for
thin metals
how does spot welding and resistance welding work
2 copper electrodes are closed around the 2 sheets to be joined
a large current is forced through creating resistance and heat joining the 2 parts together
what is spot welding and resistance welding used for
- car industry
- joining handles to saucepans
CARRY ON WITH THE NUTS
what type are screws are there
- self tapping screws
- wood screws
- machine screws
what does self tapping screws do
cut their own thread
what does self tapping screws require
a plain hole before use
what is self tapping screws used for
metals and plastics
what does self tapping screws usually have
coarse thread and a tapering diameter
what is wood screws a form of
self-tapping screws
what is required with a wood screw
pilot hole for the shank and possibly a countersink
what are machine screws used for
metal objects or plastic
what does machine screws rely on
-the hole they are being inserted having a threat cut internally
- have an evenly pitched thread and a constant diameter - typically 2mm - 20mm
what do bolts have
a plain shank between the head and the thread
how do you use a bolt
a bolt is inserted into a hole that is slightly larger than itself and the screw threads are secured into a nut with a washer in between
what is the shape of a nut
plain hexagonal, locking nut
what does a wing nut do
allows the joint to be tightened without tools
why are washers an esential part of a boted joint
- help to prevent damage to the components being joined
- some prevent loosening of the connection
what are the most essential washers
plain and spring washers
what are riverts associated with
joining flat sheet metal components
what are the drawbacks of riverts
both sides of the joint need to be accessed
what do pop riverts consist of
consist of a hollow alluminium alloy rivert and steel pin
what is a rivert gun used for
used to pull the steel pin through the rivet so that it clamps against the back of the components
