Metals
Types Of Metals
the range of metals are classifeid as Non Ferrous and Ferrous
Metals can then be seperated under these headings into Alloys and Non Alloys
Ferrous Metals: Metals that contain iron and carbon
Non Ferrous: Metals that do not contain Iron
Ferrous Alloys: Mixture of two metals, atleast one of the metals contains iron and carbon
Non Ferrous Alloys: Mixture of two metals that do not contain carbon or iron
Ferrous: Mild Stell; Strong and cheap, can rust ( car bodies and white gold)
High Carbon Steel; Harder than mild steel, hard to work and can rust (drills and files)
Cast Iron; Hard, Brittle under impact ( brake discs, engines)
Non Ferrous: Aluminium; Leightweight, cheap, rusts easily ( car bodies, screws, nuts)
Brass; Strong, ductile, looks good ( door furniture, door nobs, electric parts)
Copper; Soft metal, good conductor of electricity ( wires, pipping)
Ferrous Alloys:Stainless Steel
High Speed Steel
Die (tools) Steel
Non Ferrous Alloys:Brass
Bronze
Duralumim
Gold is the only metal that is extracted and usable without processing, all other metals are from ores
Common Metal Ores:
Iron
Copper
Aluminium
Lead
Tin
Zinc
25% of the earth crust is made up of metal ores, Aluminium is the most common followed by iron
The rarer the metal the more expensive
Thursday, 8 October 2009
Monday, 5 October 2009
Timbers
Polyurethenevarnish cab ve sprayed onto wood rather than coated on with a brush, can get gloss or matt finish
Wood stain can be used to protect the wood aswell as staining it another colour
Oils can be rubed into the wood, no gloss affect, inhances the colour of the wood
Preservatives - tanalised timber, no varnish needed as ot has been injected, used for sheds, decking, injecting the wood inhances its like by 4x as long, is seasoned in a kilm and takes the moisture out of the wood, exterior wood not interior
Paint - must put a primer on it before used, primer seals the timber from moisture and lets the paint stick to it.
Wood stain can be used to protect the wood aswell as staining it another colour
Oils can be rubed into the wood, no gloss affect, inhances the colour of the wood
Preservatives - tanalised timber, no varnish needed as ot has been injected, used for sheds, decking, injecting the wood inhances its like by 4x as long, is seasoned in a kilm and takes the moisture out of the wood, exterior wood not interior
Paint - must put a primer on it before used, primer seals the timber from moisture and lets the paint stick to it.
Man Made Board
Uses waste material, has no moisture in it not allowing the board to bend
MDF - medium density fibreboard, Cheap, fine wood chippings in glue and compressed together to forum a sheet, no structure, will blunten saw due to the glue being harder than the wood
Plywood - most used for furniture because its veneered (product underneath with a coating on top to make it look aesthetically pleasing) there are two types of vaneer : sliced and rotory
, the grain on each sheet goes opposite to make the plywood have a stronger structure and stop it bending
Chipboard - wood chips glued together, blunts the saw like MDF, can be as thick as you like, very strong
Hardboard - cheap, very weak, fibreous, absorbs water, used for backing on some furniture like cupboards
Blockboard - Vaneered on the top, wood stuck together in the middle in several sections
Flexy ply - machined with grouves in allowing it to bend in a certain direction
Aeroply - Used for outer skin of aircraft, very expensive, has a stright grain, the wood used to form it is Beach
Maplex - new MDF, high grade MDF, High Desity
Man made board has no iragularites such as Knots
thickness of board goes in multiples of 3mm (3,6,9,12,15,18,21,24) and a height of 1120 mm
MDF - medium density fibreboard, Cheap, fine wood chippings in glue and compressed together to forum a sheet, no structure, will blunten saw due to the glue being harder than the wood
Plywood - most used for furniture because its veneered (product underneath with a coating on top to make it look aesthetically pleasing) there are two types of vaneer : sliced and rotory
, the grain on each sheet goes opposite to make the plywood have a stronger structure and stop it bending
Chipboard - wood chips glued together, blunts the saw like MDF, can be as thick as you like, very strong
Hardboard - cheap, very weak, fibreous, absorbs water, used for backing on some furniture like cupboards
Blockboard - Vaneered on the top, wood stuck together in the middle in several sections
Flexy ply - machined with grouves in allowing it to bend in a certain direction
Aeroply - Used for outer skin of aircraft, very expensive, has a stright grain, the wood used to form it is Beach
Maplex - new MDF, high grade MDF, High Desity
Man made board has no iragularites such as Knots
thickness of board goes in multiples of 3mm (3,6,9,12,15,18,21,24) and a height of 1120 mm
Structure Of Wood
wood is a fibreous material
fibres run along the trunk
55% of tree is cellulose, 28% lignin resin, this holds the tree together
What happens to timber before its the product
harvest - cut the tree down
conversion - cut the trunk into boards
seasoning - reducing the moisture content, can be dryed naterialy or in a kilm
fibres run along the trunk
55% of tree is cellulose, 28% lignin resin, this holds the tree together
What happens to timber before its the product
harvest - cut the tree down
conversion - cut the trunk into boards
seasoning - reducing the moisture content, can be dryed naterialy or in a kilm
Natural Timbers
Lumer has been failed, still in its log shape
Wood is the material
Timber is the processed material
Hardwoods - Diciduous trees, loose there leaves in the winter
(Ash, oak, beech, teak, walnut)
Slow growing
Softwoods come from coniferous trees, trees with needles and cones, evergreens
(larch, spruce, scots pine, douglas fur)
Fast growing
Indiginous - point of origin (oaks from england)
Softwoods are cheaper to buy due to it being able to grow quicker, it is a more sustainable source than hardwoods.
The age of a tree can be found out by counting the amount of anual rings
the dark rings show the winter months, light rings show the summer, thickness determins how long the summer or winter was. In the winter the lines are dark due to the resin protecting the tree from the cold and in the summer less resin as it isnt as cold.
FSC symbol is placed on wood to show it is from a sustainable source, for every tree they cut down they replace it with two.
Wood is the material
Timber is the processed material
Hardwoods - Diciduous trees, loose there leaves in the winter
(Ash, oak, beech, teak, walnut)
Slow growing
Softwoods come from coniferous trees, trees with needles and cones, evergreens
(larch, spruce, scots pine, douglas fur)
Fast growing
Indiginous - point of origin (oaks from england)
Softwoods are cheaper to buy due to it being able to grow quicker, it is a more sustainable source than hardwoods.
The age of a tree can be found out by counting the amount of anual rings
the dark rings show the winter months, light rings show the summer, thickness determins how long the summer or winter was. In the winter the lines are dark due to the resin protecting the tree from the cold and in the summer less resin as it isnt as cold.
FSC symbol is placed on wood to show it is from a sustainable source, for every tree they cut down they replace it with two.
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