Which metal is used in metalwork?
Metals are hard, non-adhesive, cold and smooth, and they are very often shiny and strong. They are also ductile and malleable and do not break easily. Metals are very good conductors of electricity, sound and heat. When the temperature rises, they expand, and when it falls, they always contract. They can be easily welded to other metals.
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The study of Metals has been one of man's greatest pastimes for a long, long time. And you think that there are a lot of better pastimes, sleeping being one! But ever since the Bronze Age there has been a huge connection between the ascent of man and Metals. Although the course that you are doing is properly called 'Materials Technology' there is still more of an emphasis on Metals than the other type of material. So you must develop a good knowledge of the basics.
Metal as a topic is a huge one, so below we have broken it down into sections that give brief explanations of what the section is about. From there you can then go on to get more detailed information.
There are a lot of metals used in Engineering; however, those based on iron are by far and away from the most important and widely used. As a result, metals are broken into 2 categories. Those that are based on iron and those that are not. Ferrous is the Greek word for iron and is the name given to all metals which are based on this metal. Steel is a Ferrous metal because its main constituent is iron. A quick and easy way to tell if a metal is Ferrous or not is to use a magnet. Iron is magnetic and as a result, so are all Ferrous metals so that a magnet will stick to a Ferrous metal.
Pure iron is of little use as an engineering material because it is too soft and ductile. When iron cools and changes from a liquid to a solid, most of the atoms in the metal pack, tightly together in orderly layers. Some, however, become misaligned, creating areas of weaknesses called dislocations. When a piece of iron is put under stress, layers of atoms in these areas slip over one another, and the metal deforms. This begins to explain the ductility of soft iron. By adding carbon to the iron; however, we can produce a range of alloys with quite different properties. We call these the carbon steels. An alloy is a mixture of two or more chemical elements, and the primary element is a metal.
Knowing what Ferrous metals are, you should be able to guess what Non Ferrous metals are. They are metals that are not based on iron. Examples of Non Ferrous metals are Aluminium, Brass, Copper, Lead, Tin, etc. Again you can use a magnet to tell that metal is Non-Ferrous. Naturally, the magnet will not stick to a Non-ferrous metal.
They are metals that don't contain iron. They have a lot of uses, but they are often expensive because they are more difficult to extract.
The Production of Iron
Iron is very rarely found in its natural form. It has to mine in the form of Iron Ore. Iron Ore contains large amounts of materials that are not wanted, such as rocks, clay, and sand, and they have to be removed. The iron itself is chemically combined with Oxygen and is called Iron Oxide. In order to remove all of the impurities, Iron Ore has to be Smelted, and this is done using a Blast Furnace.
The Production of Steel
You see a lot more steel around you than you do iron. Think of cars, cutlery, even the kitchen sink. Steel is made from iron mixed with carbon. The two methods of producing Steel from Iron are The Basic Oxygen Process and the Electric Arc Process.
An alloy is defined as a mixture of two or more metals. Engineers make alloys in order to improve the properties of pure metals, that is those that you can find in the Periodic Table Of The Elements. Take copper, for example. A long time ago a man found, (probably by accident), that if he mixed Copper and Tin, the result was another metal that was tougher and harder but kept the basic properties of both Copper and Tin. This new metal was called Bronze. Now the man had a "new" metal that allowed him to create a lot more items. This new age in history was called the Bronze Age. Later it was found that mixing Copper and Zinc resulted in a shiny, gold-like metal which we now call Brass. The Alloying of metals is an industry in itself nowadays. There are so many different types of Steels, Aluminium and other non-pure metals that engineers are kept busy enough creating and improving. Be careful, Plain Steel is not an Alloy, by definition, as it is only a mixture of Iron and Carbon. Carbon is not a metal. Having said that most Engineers call plain steel an alloy. However, other types of Steels are Alloys as there are small amounts of other metals mixed in.
Copper has a reddish brown colour, and after weathering turns a green colour. It is Ductile and Malleable. It is also an excellent conductor of heat and electricity and is easy to Solder and Braze. Copper is the base metal in the alloy metals of Brass and Bronze. Copper hardens with age and with working. This is called Work Hardening. This can be reversed by Annealing, which is where you heat up the copper to red hot and then quenches it in water. Copper has many uses, but because it is becoming expensive to produce, and is found less abundantly in the Earth's crust, other metals are being used for the same purposes more and more. Some of copper's uses are Electrical wiring, water plumbing and piping, roofing, soldering iron bits, in the manufacture of Brass and Bronze, etc.
Copper is a soft, malleable, and ductile metal with high thermal and electrical conductivity. It is a pinkish-orange colour. Copper is commonly used in the construction industry to form pipes and tubing, as it is malleable and joints can be easily formed by soldering. It is also used as a cladding material, sometimes allowed to oxidise to a blue-green colour.
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Lead as you should know is highly toxic, and has been removed from petrol, giving Unleaded Petrol. As a result, you will not be using this material in the Metalwork room. However, it is good to know something about it. Lead has the highest density of the common metals, making it relatively heavier. After weathering it has a dull grey colour, but it is slightly shiny and greyish-blue when cut. It is soft and Malleable. It is actually so soft that you could bend 5mm sheet Lead in your hands without any difficulty, but don't try this, take our word for it. Even Though Lead is toxic, it still has many uses: car batteries, protection against X-rays, chimney flashing, etc.
Lead is a heavy metal that can be toxic when absorbed into the body.
In construction, Lead is used due to its ductility to form roofs and other cladding panels as well as windows, linings for cornices, tanks, copings, gutters and downpipes, flashing, and so on. It is also a component of soft solder.
Historically it was used in paints and pipework. Most lead-based paints were banned from sale to the general public in the UK in 1992. It has not been used for water pipes since 1970; however, it may still be present in older properties. It is recommended that lead pipes should be replaced.
Brass is an alloy of Copper and Zinc. The percentage of Zinc in the alloy varies to give the Brass different properties. Brass has a yellow "gold" like appearance and is considered to be very pretty metal. Even Though it is a relatively hard material is reasonably easy to machine. When filing, hacksawing or turning on the Lathe, the Brass breaks off into small chips. Brass has good resistance to corrosion. Brass has many uses, and many are as a result of its appearance: plumbing fittings, screws, brazing spelter, electrical fittings, ornamental work, etc.
What are the common metals used in the construction industry?
Chosen for their durability, strength and resistance to weather, metals used in the construction industry serve a wide range of functions. The most common of them are carbon steel, aluminium, copper tubing and stainless steel, which each have their particular qualities and ideal uses. As a whole, however, these metals are ubiquitous in the world of buildings and architecture, in applications both small and large.
Aluminium making up 8% of the Earth's crust is the third most common element. It is used widely in the engineering industry because of its properties which make it extremely useful, and with alloying, there are many different types of Aluminium for different uses. Some of these are Tin cans, Aluminium Foil, Structural Elements, Guttering, Window Frames, Aircraft Bodies, Vehicle Bodies, Electrical Wire, etc.
Because of its ductility, aluminium can be formed into many shapes and profiles. Aluminium wall cladding systems are commonly used for building exteriors, with large wall panels requiring fewer joints, resulting in time-efficient installation. Today, aluminium is the second most used metal in buildings after steel, used for roofing, flashing, wall panels, windows and doors, spandrels, and so on.
Aluminium is also commonly used in the industry because it is resistant to corrosion, highly conductive and ductile. Because it is resistant to harsh weather, the metal is used in windows, doors, and wire, as well as outdoor signage and street lights. The metal is processed into sheets, tubes and castings, and also used to build automobiles and trucks, as well as bicycles and marine vessels. HVAC ducts, roofs, walling and handles made of aluminium are also frequently found in the building industry.
Carbon steel is one alloy that is prized in the construction industry for its hardness and strength. It is typically used to make beams for structural framework, plates for highway construction, and rectangular tubing for welded frames, trailer beds, and bridges. It is also a material of choice to make rebar and hollow structural sections (HSS). Made by mixing carbon and iron together, carbon steel is classified on a scale of "mild" to "very high," depending on how much carbon is present in the metal.
Mild Steel: carbon content between 0,1% and 0,3%. Properties: less ductile but harder and tougher than iron, grey colour, corrodes easily. Uses girders or beams, screws, nut and bolts, nails, scaffolding, car bodies, storage units, oil drums.
Medium carbon steel contains between 0,3% and 0,7% carbon. Properties: harder and less ductile than mild steel, tough and have high tensile strength. Uses: it's used for the manufacture of products which have to be tough and hard wearing like gears, tools, keys, etc
High carbon steel contains between 0,7% and 1,3% carbon. Properties: Very hard and brittle material. Uses: It's used for cutting tools and products which have to withstand wear such as guillotine, springs, etc.
Stainless steel is iron and chromium alloys. A wide range of steels is available with chromium content between 13% and 27%. Properties: Chromium prevents rusting with an oxide film. Ductility, hardness and tensile strength. It's also a shiny attractive metal. Uses cutlery, sinks, pipes, car pieces, etc.
Grey Cast Iron is an alloy of iron (94%), carbon (3%) silicon (2%) and some traces of magnesium, sulphur and phosphorus. Properties: brittle but extremely hard and resistant, it corrodes by rusting, Uses pistons, machinery parts, streets lamps, drain covers, tools.
Copper tubing, which comes in two main types, is often used to construct pipes in buildings. Rigid copper tubing is ideal for hot and cold tap water pipes in buildings. Soft copper, on the other hand, is frequently used to make refrigerant lines in HVAC systems and heat pumps. Copper ductile, malleable metal is resistant to corrosion from water and soil and is also recyclable. Copper tubing is also easily soldered, forming lasting bonds. All of these properties make this metal ideal for piping and tubing.
Stainless steel is among one of the oldest known building materials. It was used centuries ago to construct structures that still stand today, thanks to the corrosion and stain resistant properties of the metal. Some of the most famous architectural structures, such as the Chrysler Building in New York City, rely on stainless steel for its strength, durability and reliability. Stainless steel is an alloy of several different metals, the amounts of which can be adjusted to create different grades of stainless steel with different properties. The most common grade is 301, which is ductile and easily welded. It can be found in roofing, structural applications, handrails and balustrading, architectural cladding, as well as in drainage components.
What are the three types of metal ceilings?
The three systems Cootes refers to are the clip-in, hook-on and lay-in varieties, all of which differ in the way they attach to a ceiling grid and also in the finish and functionality they can achieve.
These grid systems are also used with other types of ceiling tiles such as mineral fibre. Still, due to their composition, a metal pan ceiling can achieve different shapes and finishes that non-metal varieties cannot.
Following is a list of the types of grids and their most suited applications. More importantly, the list will describe ways you can utilise metal pan with that associated grid to take your ceiling to places unseen in non-metal applications.
Above ceiling tiles lay on a T-shaped runner such as top-left. Right: NAB Docklands building utilises a perforated metal lay-in tile system. The grid of a lay-in tile system is fully seen and is the most common product in standard office buildings.
Tiles are simply placed on a T-shaped runner (above left), generally between 10 and 25mm, and can be easily installed and demounted as individual tiles.
Cootes drew attention to the flexibility that lay-in tiles afford to maintenance requirements and services that need to access the ceiling void above the tiles.
"Lay-in tiles are extremely easy to remove and flexible for services such as electricians, plumbers, air condition and that sort of thing," he said.
"They are also the easiest to move around when renovating and shifting office spaces."
Metal pan versus non-metal pan:
Open-cell lay-in tiles are one of the many options afforded to those who choose metal ceilings. This one is from Armstrong.
Cootes explains that because of their material composition and the way they are manufactured, metal pan (unlike mineral fibre boards) can achieve vastly different textures with a lay-in system.
"One way you can achieve texture with a lay-in metal pan ceiling system is with tegular edged tiles that drop down in different thicknesses," explains Cootes.
"You might have tegular edge tile which is 8mm high, next to one that's 16mm and then one that's 24mm, and you can stagger these to achieve a different look."
"This cannot, for argument's sake, be achieved with a mineral fibre board."
Ceiling tiles on a clip-in system do just that - they clip on to the suspended grid and therefore conceal the grid from view. Manufacturers have their own unique clip-in systems that match their boards but generally they all consist of a spring tee runner from which boards clip on to.
Cootes explained that clip-in tiles involve a special demountable tool to access the ceiling plenum and thus aren't as convenient for services as a lay-in tile. They can, however, withstand upward cleaning pressure that lay-in tiles can't, so cleaners can remove stubborn marks without damaging or moving the tile.
"An answer to their lack of accessibility, however, would be the hinged-down system," said Cootes.
"The hinge-downs aren't used throughout the whole ceiling, just in places that need to be accessed by services."
Metal pan versus non-metal pan:
Clip-in tiles conceal the suspended runners and create a feature of ceilings. They are also resistant to upwards cleaning pressure and will not dislodge with this process. Image: Armstrong.
With a clip-in system, the flexibility of metal ceilings flourishes; they come in the standard rectangular shapes, a variety of tegular edged finishes, and in tubular, hinged and baffled forms.
Because they are fixed, they can achieve curvatures and textures that other systems can't.
Hook-on systems attach to a suspended J or Z suspension rail and can be hung in a variety of square, rectangular, trapezoidal and triangular shapes.
They are a concealed system that is not fixed and removed with a special tool so tiles can be lifted out and ceiling voids can be accessed relatively easily.
Metal pan versus non-metal pan:
Metal pantiles can achieve a multitude of texture and colour options. Cootes says most have a 25-year guarantee. Image: SAS International.
A hook-on, like a clip-on system, accentuates the flexibility of metal pan ceiling tiles because it offers a multitude of design options.
"You can also achieve almost anything with a hook-on ceiling by having things custom made," said Cootes.
Due to their composition and strength, metal ceilings can achieve finishes and longevity measures that mineral fibre tiles cannot.
Cootes alerted us to finishes such as baffle and wave effects, polished stainless steel tiles that achieve a mirror finish and the plethora of colours that can be added to the tiles.
What are the metalworking techniques?
The techniques of metalworking follow the same principles, whether the scale of the design is industrial or sculptural, or even at the tiny scale of a ring or a pair of earrings. Furthermore, many of the basic techniques also relate to work in other media. Engraved plates, for example, are used in printing, and ideas such as applique and repose can be used in media as different as textiles and ceramics. If you would like to see examples of metal arts by contemporary craftsmen, try this link.
Annealing. The process of heating work-hardened metal in order to restore its malleability.
Applique. The technique of creating a design by soldering or granulating cut-out shapes of sheet metal to another metal surface.
Casting. The process of shaping a molten metal by means of a mould.
Chasing. A technique for a surface is embellishing of metal accomplished by driving pointed tools into the metal.
Enamelling. The fusing of a glassy substance onto metal. Enamels are combinations of flux and metal oxides (for colour). Cloisonne is one of the better-known enamel techniques.
Forging. Hammering metal on an anvil or form in order to shape, thin, or stretch it.
Granulation. A type of surface treatment in which small metal beads or wires are fused onto a metal foundation, or to one another. Can be done in gold or silver.
Malleability. The degree to which a metal is capable of being extended or shaped by forging or stretching, without cracking or breaking.
Piercing. Sawing lines or designs into sheet metal.
Raising. Forging sheet metal so as to shape it into 3-dimensional objects.
Repousse. A technique of pushing the metal out from its reverse side using hammers and punches in order to create a low relief design on the front.
Reticulation. The fusing or melting of a metal surface to create texture.