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

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

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.

Sheet Metal Bending

Used to bend metals

Done using a Press Brake bending machine

Process involves

-Positoning a sheet of steel between a punch and V-shaped die. This punch then moves

down forcing the sheet to bend.

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

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

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)