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METALS - Coggle Diagram
METALS
NON-FERROUS
Brass
Copper
Titanium
The aerospace industry, building structures and medical prostheses (artificial limbs).
100% titanium
Silvery white, shiny; light; very hard and strong.
Aluminium
Bronze
100% bronze
Boat propellers, filters, church bells, sculptures, nuts, bearings and cogs.
Resistant to general wear and corrosion.
Magnesium
Tin
Lead
Batteries, protective measures against nuclear radiation.
An additive in glass to increase its hardness and add weight.
100% lead
Silvery grey; soft and malleable; lead fumes are toxic when inhaled.
FERROUS
Pure Iron
Properties
Greyish white colour.
Good magnetic properties.
Disadvantages: only melts at high temperatures; difficult to machine; fragile and brittle.
the concentration of carbon is between 0.008% and 0.03%.
Rarely used.
Used in electronics and electrical components.
Cast Iron
Machine parts, casing for engines, stands for machines, pistons, street lamps, drain covers ...
Very hard and resistant.
the concentration of carbon is between 0.008% and 0.03%.
Steel
between 0.03% and 1.76%
Very hard and resistant. Very resistant to traction. Easy to weld. Alloys with chrome and nickel to make stainless steel.
Structures in construction, car chassis, boats, trains, machinery, tools, screws, domestic appliances, kitchen utensils, taps ...
Metals are substances from minerals which contain one or more metallic elements, and sometimes non-metallic substances such as carbon.
Charasteristics:
They are good electrical, thermal and acoustic conductors.
They are ductile and malleable.
They are tough.
They melt at high temperatures so they can also be used for welding.
They expand when the temperature rises and contract when it cools.
Some are magnetic and are attracted to magnets.
Most of them rust when they come into contact with air and oxygen.
They can be recycled and reused.
Some of them, such as lead or mercury, are toxic for the environment.
Finishing
Buffing: This technique also produces a shine. A mechanical buffing wheel is used with a steel disc or roll, which can be abrasive.
Polishing: This technique produces a shine, using a polishing wheel with revolving, abrasive wheels or strips.
Lapping: A lapping machine has a vertical handle and abrasive discs. This is usually used for finishing openings and conical surfaces, and is very accurate.
Grinding: A grinder is used to refine surfaces to precise, accurate dimensions and to remove any imperfections. We can use it on flat pieces or cylinders.
Coating. This technique is used to protect the metal. The metal is coated in plastic or other metals, e.g. zinc, silver, gold, nickel or chrome. This technique is called galvanisation. Paints, varnishes and enamels can also be used.
JOINING
PERMANENT JOINTS
Oxyacetylene welding: An oxyacetylene blowtorch is used which can reach temperatures of over 3000°C.
Rivets: This is a metal tube with a head at one end. It is inserted into the openings of the pieces to be joined together and then, with a tool known as a riveter, a head is placed onto the other end, joining the pieces.
Press fit joint: In this type of joint, a pin with a slightly larger diameter than the opening is inserted into the opening using a hammer or pressure. Sometimes you have to pre-heat the hollow section to dilate the opening.
Hard soldering: Brass or copper is heated with a blowtorch to a temperature of 800°C.
Adhesives: There are different types: hot melt adhesives, waterproof and instant glues. Before gluing the pieces together, you should scratch the surface to improve its adherence.
Soft soldering: We use a tin-lead alloy. This is heated with an electric soldering iron, which reaches temperatures of 400°C.
TEMPORARY JOINTS
Threaded stay bolts: This bolt has grooves at both ends, but the middle section is smooth.
Keyed joint: With a piece of metal called a key, you can join two objects by putting the key in a groove.
Screws: A screw joins one piece to another where there is a threaded hole. If the screw threads the hole as it is going in, we say it is a self-drilling screw.
Splined shafts: The two pieces have grooves so that they fit together when joined together. The assembled pieces can rotate.
Nuts and bolts: The bolt is inserted through the pieces that need to be joined together. Washers are used so that the pieces don't break and to secure the joint.
Sliding joints: Two objects that are joined together that can move or slide over each other.