Tuesday, 24 November 2009
Friday, 9 October 2009
MIG Welding
Metal Inner Gas
- Uses a electric curren and not a flame.
- The more ampage you use the more power u get
- The shoud is used to release gas and keep the metal clean
Safety
- Light can burn skin, retena
- Wear mask, light sensative
- Wear a Jacket and gloves
Prep
- Set ampage of welder for the thickness of metal
- Metal must be earthed in order for the circuit to complete itself
Metals
- becoming less commonly used
- Ferrous metals
- Non ferrous metals
- Non ferrous alloys
Ferrous metals
- Iron + carbon
- Rusts and oxidises
Non Ferrous metals
- Dont contain iron
Ferrous Alloy
- mix of metals that contain iron and carbon
Non Ferrous alloy
- Mix of metals that doesnt contain iron
Ferrous Metals
- Brittle, strong inpact strength
Mild Steel
- 0.3% carbon
-rusts easily, cant be hardened or tampered
- car bodies, screws
High-carbon Steel
- Harder than mild steel
- Difficult to work and rusts
- Drills and saws
Cast Iron
- Hard, brittle under compace
- Machine parts, break discs
- Ferrous metals
- Non ferrous metals
- Non ferrous alloys
Ferrous metals
- Iron + carbon
- Rusts and oxidises
Non Ferrous metals
- Dont contain iron
Ferrous Alloy
- mix of metals that contain iron and carbon
Non Ferrous alloy
- Mix of metals that doesnt contain iron
Ferrous Metals
- Brittle, strong inpact strength
Mild Steel
- 0.3% carbon
-rusts easily, cant be hardened or tampered
- car bodies, screws
High-carbon Steel
- Harder than mild steel
- Difficult to work and rusts
- Drills and saws
Cast Iron
- Hard, brittle under compace
- Machine parts, break discs
Manufactured Board and Finishing Woods
Manufactured Boards
Sizes
8 foot x 4 foot, 2.42 metres x 1.22 metres
Plywood
- strong, layered up of different veneers (grains counteract)
- Mareen ply, water proof
MDF
- medium density fibreboard
-wood chippings mashed up and adhesive added and then compressed to form wood
- glue will cause blades to blunt
-cheap
Hardboard
- Usually used for filling gaps
- Weak fibres will separate if it gets wet
- Furniture blacks
Chipboard
-Kitchens, table
-Made of thicker chipping, glue and compressed
- Add coating to make it stronger
Blockboard
-Sections of timber joined together with 2 venners (aesthetic reasons)
- scraps used
Aeroply
- Designed to bend
- used in aeroplanes
Maplex
- "posh" mdf
- used for furniture
- easier to machine
ALL A JOINT MIX OF DIFFERENT MATERIALS!
Veneers- slice of wood
Slice veneering, cutting a thin layer of wood off a sqaured sheet of wood
Rotery veneer, wood is spun so when the blade is put in you get a thin sheer of veneer, like pulling paper off a toilet roll.
Finishing Woods
- water or oil based
- When you varnish you brush a plastic coat onto it
- Must finish when ANY material is used
Plyurethane Varnish
- Plastic based varnish
- Most common
- Glass satin
Wood Stain
- changes the colour
- also a varnish
- no varnish? add it!
Oils
- used for furniture
Preservatives
- Applied to timber outdoors
Paint
- to ismply apply colour to timber
Injected preservative (tranalise = processed)
- Processed= injected with tranalise
- Processed where wood is dried out
- Shed fencing
- Only injected into 5mm of walls of timber, on face
- Legthens life by 4x
Sizes
8 foot x 4 foot, 2.42 metres x 1.22 metres
Plywood
- strong, layered up of different veneers (grains counteract)
- Mareen ply, water proof
MDF
- medium density fibreboard
-wood chippings mashed up and adhesive added and then compressed to form wood
- glue will cause blades to blunt
-cheap
Hardboard
- Usually used for filling gaps
- Weak fibres will separate if it gets wet
- Furniture blacks
Chipboard
-Kitchens, table
-Made of thicker chipping, glue and compressed
- Add coating to make it stronger
Blockboard
-Sections of timber joined together with 2 venners (aesthetic reasons)
- scraps used
Aeroply
- Designed to bend
- used in aeroplanes
Maplex
- "posh" mdf
- used for furniture
- easier to machine
ALL A JOINT MIX OF DIFFERENT MATERIALS!
Veneers- slice of wood
Slice veneering, cutting a thin layer of wood off a sqaured sheet of wood
Rotery veneer, wood is spun so when the blade is put in you get a thin sheer of veneer, like pulling paper off a toilet roll.
Finishing Woods
- water or oil based
- When you varnish you brush a plastic coat onto it
- Must finish when ANY material is used
Plyurethane Varnish
- Plastic based varnish
- Most common
- Glass satin
Wood Stain
- changes the colour
- also a varnish
- no varnish? add it!
Oils
- used for furniture
Preservatives
- Applied to timber outdoors
Paint
- to ismply apply colour to timber
Injected preservative (tranalise = processed)
- Processed= injected with tranalise
- Processed where wood is dried out
- Shed fencing
- Only injected into 5mm of walls of timber, on face
- Legthens life by 4x
Thursday, 8 October 2009
Sand Casting
Process involves
-pouring molten meal into a prepared sand mould
-It is then left to solidify
- 2 holes are left either side of the mould
-1 hole is used to put the molten metal in and the other is to let out any gases
-once the mould has solified the sand is then removed and the cast is complete.
Friday, 2 October 2009
Plastic Extrusion
Step 1 - Thermoplastic powder is placed in the hopper; this powder then falls into the rotating
Achimedean screw. Which in turn pushed the material towards the heated section of the
extruder.
Step 2 - Heaters soften te plastic, forced threw the die by the rotating screw.
Step 3 - On exiting the die, pastic product is the cooled using a water jet.
Step 4 - Further along the transfer table, product is cut for the required legth.
Works like a childs plasticine toy, it pushed the plastic threw the holes
making a long tube. e.g piping
Hard wood, Soft wood
Hardwood
Deciduous tree, looses leaves in autumn
Ash, Oak, Beech, Teak, Walnut
Softwood
Coniferous trees, has needles or cones
Larch, Spruce, Scots Pine, Douglas Fir
Deciduous tree, looses leaves in autumn
Ash, Oak, Beech, Teak, Walnut
Softwood
Coniferous trees, has needles or cones
Larch, Spruce, Scots Pine, Douglas Fir
Thursday, 1 October 2009
Wood laminating
Wood Laminating
Laminating - something thats built up in layers
Vaneer - Often used in laminating
Plywood is made from thin sheets of wood, called veneers which are glued together.
Plastic laminated - many layers of resinimpregnated kraft paper.
When wood is cut into thin veneers it can be bent into a mould to form complex shapes.
Laminating Methods
- Using male and femail mould
- Using a vacuum bag or vacuum frame
Using a Vacuum bag - Layers of veneer placed together on a mould and put inside a tough plastic bag. Vacuum pump is used to suck air from bag and produce shape.
Steam Bending
-Creates curvs in wood
Uses steam to eaken the wood so that after it is taken out the machine it is very easy to bend. This happens as the lignin is weekened so the fibres can move more easily. Lignin then sets again.
This process can be done more than once.
Static and Dynamic loads
- static, doesnt move
- dinamic, does move
Planes (dinamic); made out of alluminium which expand when in the air due to a lot of air pressure
Steam Bending
Cost
-low tooling cost
-moderate to high unit cost
Quality
-Good quality and high strength due to grain alignment
Laminating - something thats built up in layers
Vaneer - Often used in laminating
Plywood is made from thin sheets of wood, called veneers which are glued together.
Plastic laminated - many layers of resinimpregnated kraft paper.
When wood is cut into thin veneers it can be bent into a mould to form complex shapes.
Laminating Methods
- Using male and femail mould
- Using a vacuum bag or vacuum frame
Using a Vacuum bag - Layers of veneer placed together on a mould and put inside a tough plastic bag. Vacuum pump is used to suck air from bag and produce shape.
Steam Bending
-Creates curvs in wood
Uses steam to eaken the wood so that after it is taken out the machine it is very easy to bend. This happens as the lignin is weekened so the fibres can move more easily. Lignin then sets again.
This process can be done more than once.
Static and Dynamic loads
- static, doesnt move
- dinamic, does move
Planes (dinamic); made out of alluminium which expand when in the air due to a lot of air pressure
Steam Bending
Cost
-low tooling cost
-moderate to high unit cost
Quality
-Good quality and high strength due to grain alignment
Typical Applications
-Boat building
-Furniture
-Musical instruments
Related Processes
-CNC machining
-Wood laminating
Suitabilty
-One-off to high volume production
Speed
-Slow cycle time (up to 3 days)
Tuesday, 29 September 2009
Thursday, 10 September 2009
Wood
- Ceramics; made from clay.
Timber – A sustainable natural resource
Soft wood – Coniferous trees, grow quicker, cheaper
Hard wood – Slow growing, deciduous, slow growing, more expensive
Quarter saw timber – cut the wood so all the pieces got shorter annual rings, more waste but more stable.
Timber – A sustainable natural resource
Soft wood – Coniferous trees, grow quicker, cheaper
Hard wood – Slow growing, deciduous, slow growing, more expensive
Wood is fibrous with fibres running along the length of the trunk.
- 55% cellulose (fibres), 28% lignin (glue)
- Fibre reinforced polymer
Life cycle up until production:
- Harvest
- Conversion, cutting into boards
– Slab sawn or Quarter sawn
- Seasoning
– Reduce moisture content
- Board Preparation
– Sawing to size, planning
Quarter saw timber – cut the wood so all the pieces got shorter annual rings, more waste but more stable.
Slab saw – Simply cut in lines so there is no waste however you get some pieces with big annual rings. Less waste, less stable.
- Physical strength; stronger along the grain than across it
- Aesthetic properties; colour, complex or simple grain structure
- Protection; Dry and wet rot, insect attack
- Operating conditions; Where will the timber be used? Outside? Inside a heated house? -
-Sustainability/ Environmental issues; Use sustainable sources
- Size of boards available
I should never have purchased
Headphones
A few weeks ago my ipod headphones broke so i invested in a new basic pair. The packaging explained that they were durable and would last me at least 6 months but also give out high quality sound.
A few weeks ago my ipod headphones broke so i invested in a new basic pair. The packaging explained that they were durable and would last me at least 6 months but also give out high quality sound.
The headphones aesthetics were of good quality as the ywere just simply black and simple, there was also a small headphone design in the earpiece which advertised the individuality of the set. Another plus point in the headphones that many others fail to have is a wire that is plenty long enough to reach both ears from the inside of your trouser pocket without being tugged from your ears.
However although the aesthetics and wire length was very good the headphones were actually of very poor quality. The sound was nowhere near as good as it had been advertised as it was crackly and broken sound. Due to poor wire connection the sound was also constantly cutting out and has to be positions perfectly in order for them to work. This of course is and inconvenience when you want to listen to music whilst exercising.
It was obvious that very little anthropometric data was taking into account during the production of these headphones. This was clear as it took great care to insure the main ear piece stayed in the place even when doing something simple like sitting down, so it was near enough impossible to take up any physical activity at the same time.
The only solution to this was to chuck them away and buy a new pair, which this time are of good quality.
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