materials for technical use (ii) metal
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Materials for Technical Use (II): Metal
Department of Technology I.E.S. El Molinillo
Guillena
© Antonio Jesús Romero
Metal Properties Metal is a good conductor of heat and electricity
High mechanical endurance
High fusion temperature Metal is a heavy materialCast Iron Steel Copper Tin Zinc Aluminum Magnesium Titanium
Tensile Strength 18 kg 70kg 18kg 5kg 3kg 10Kg 18kg 70kg
Mass(per m3) 7600kg 7800kg 8800kg 7300kg 7400kg 2700kg 1700kg 4500kg
Fusion temperature 1100ºC 1500ºC 1083ºC 231ºC 419ºC 660ºC 650ºC 1800ºC
It´s a tough material
Some of them have magnetic properties It´s an easily recyclable material
It´s a ductile, malleable material
Metal Properties
Classification of MetalsWorld Metal Production
Metals are classified in two groups:
oFerrous Metals: iron and its alloys.
oNon-Ferrous Metals: metals that do not contain iron .
This is because iron is the most used metal in the world
Ferrous Metals
Iron is an abundant metal.Iron is fragile and brittle.Iron rusts easily.Iron has very good magnetic properties.
Pure iron
Due to his low endurance, pure iron is not used. So it´s mixed with a little amount of carbon obtaining ferrous alloys.
How changes carbon the iron properties?A bigger amount of carbon in the ferrous alloy increases the hardness
but decreases the tenacity, so the alloy becomes more fragile.
Soft Iron( C<0,1%)
It´s like pure iron. At first it was very used because it was easy to obtain. At present time it´s used to make electromagnet nucleus thanks to its very good magnetic property.
Soft, due to its low iron content.Silvery colour.Electric and electronic applications.
Ferrous Metals: Ferrous Alloys
Steel ( 0,1%<C<2% )It´s the most used ferrous alloy thanks to its good properties.Ductile and malleable.High mechanical endurance.The amount of carbon increases hardness and fragility.
Steel mixed with other metal increases endurance (vanadium) and becomes stainless (chrome and nickel).
Ferrous Metals: Ferrous Alloys
Cast Iron ( 2%<C<5% ) Harder and more fragile than steel. It has low ductility but it´s a malleable alloy with magnesium. It melts more easily than steel.
It´s used to make complicated parts by sand casting and to make hard tools like rasps.
Ferrous Metals: Ferrous Alloys
Non-Ferrous Metals: Pure Metals Copper
Tin
•Red colour•Excellent thermal and electric conductor•Corrosion resistant•Good welding•Very ductile and malleable
•Bluish white shiny colour•Soft•Corrosion resistant•Low melting point
Zinc
Aluminum
•White colour•Very corrosion resistant
• White shiny colour• Light and good endurance• No toxic• Cheap•Stainless
Non-Ferrous Metals: Pure Metals
Magnesium
Titanium
•Very light•Expensive•Violent reaction with oxygen
•Very expensive•Endurance like steel but quite lighter.•Biocompatible
Non-Ferrous Metals: Pure Metals
Gold
Lead
•The most malleable and ductile metal•Very corrosion resistant•High thermal and electric conductivity•High economic value
•Grey colour•Very soft•Low melting point•Ductile and malleable•Very toxic
Non-Ferrous Metals: Pure Metals
Brass (Copper+Zinc)
Bronze (Copper+Tin)
•Yellow colour•Very ductile and malleable•Good tensile endurance
•Dark yellow colour•More endurance than brass•Very corrosion resistant•Good sonority•Very fluid when melting, good for molding.
Non-Ferrous Metals: Alloys
Aluminum, Copper & Magnesium
Magnesium & Aluminum
Titanium & Aluminum
•Lightness and more endurance than pure aluminum.
•This alloy is more resistant than each metal.
• Cheaper than pure titanium parts.
Non-Ferrous Metals: Alloys
Metal Obtaining
Most metals are in nature as minerals.
Chalcosite: copper rich Pyrite: iron rich Hematite: iron rich
Limonite: iron richBauxite: aluminum richPure gold
Obtaining cast iron and steelCoal
Iron ore
Limestone
Blast furnace
Torpedo ladleLadle FurnaceRefining Furnace
We can obtain cast iron from the melting of coal,iron ore and limestone at the blast furnace , then we carry it to the refining furnace using torpedo furnace and ladle furnace. In the refining furnace the amount of carbon to obtain steel decreases.
Obtaining of metals by electolysis
We use a high voltage electric current over the melted metal.Pure metal is attracted by the negative electrode (remember that metal atoms are positive).We can use this method to obtain metals like copper and aluminum.
Metal Working
To cutTo fix and to bend
To measure and to mark
To smoothTo split
To finish
To drill
To measure and to mark
To fix and to bend
Metal Working Compass
SquareSteel rule
Pliers
Vise, bar clamp and C-clamp
Scriber
To cut
To drill
Metal Working
Metal Scissors Hacksaw
DrillDrill bits
To smooth
To splitWelding Screwing Riveting
Metal Working
Rasp
Wire wool
Metal polisher
To finish
Primer
Burnished
Metal Working
Milling: we can use different mill bits to shape a piece from a block of metal.
Metal Working: Machining
Turning: we can obtain metallic parts with cylindrical symmetry.
Metal Working: Machining
Computer Numerical Control (CNC): it´s to make metallic pieces automatically and with a very high accuracy.
Metal Working: Machining
Molding and Metal Forming
Molding: Sand Casting
Sand is used to make a mold and fill this with molten metal. It allows you to make complicated parts as the engine block of a car.
LaminationWe use rolls that compress the metal to obtain sheets and metal profiles.
Molding and Metal Forming
Stamping
Die-Cutting
A metal sheet is compressed by a press to take the form of the mold.
It´s cutting pieces of a metal sheet using a press.
Molding and Metal Forming
Forge We use the fire and hammer over the anvil to shape the soft steel and get handmade pieces of metal.
Anvil
Molding and Metal Forming
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