Mig Welding

Mig: Melat Inner Gas

Mig welding uses a electric current, not a flame, the more amapage you have the highere the power, you have to chnage ampage for the thickness of the Metal.

Shrouding Gas is used to keep the meal clean when welding, when welding it is exposed to the natuaral gasses and would be porous if there was no shrouding gas.

SAFTEY

- The light that is ammited is very powerfull and can burn the retna so always wear lgiht sensitive Mask.

-Gloves to protect youir hands.

- Overals to protject clothes.

Metal

Ferrous Metals- Contain iron and carbon

- Pron to oxidisation

Non Ferrous Metals- Metals that do not contain iron.

Ferrous Alloy- Improve new properties of metal

- Mix of different metals

Non Ferrous Alloys- Moxture of two or more metals that do not contain iron

Wood Treatments

MDF: Medium Density Fiberboard

Compressed of fine wood dust and resin pressed into a board. MDF can be worked, sharpened.

Cost alot to manufacture lots as it blunts the blades quickly.


Hardboard:

Filling gaps, Made of wood fibres that have been pulped.


Chipboard:

Small chips of wood bonded together with resin and formed into sheets by compression


Block board:

Built up of a core softwood strips bonded together with adhesive and covered with a sheet of plywood.


Aeroply:

Outer skin of an air craft, think section of very high grade plywood stuck to a timber frame.

Mplex:

A new type of MDF that is used for furniture industry.


Veneering:

-Slice veneering, Taking a slice of the top of a block of timber

- Rotery veneering, slicing a rounded piece of timber continuously dill the diameter of the wood becomes very thin.


Finishing wood:

Polyurethane varnish, can be used to seal and protect the surface of the wood and gives it a smooth finish.



Wood staining:
Enhance colour.

Oils:
and be used to maintain the natural appearance of the wood.

Pewrservatives:
are generally applied to timber that is going to be used outside.

Paint:
colours and protects the wood.


Tanalised timber press, injects tanalise into the timber along the faces, Protects and preserves for 5 years and makes the wood life 4 times longer.

Wood Laminating & Steam Bending

Wood laminating

Lots of built up layers of plywood bonded together using glue and moulds to create the desired shape.

Plywood- Thin sheets of wood veneers glued together.

Plastic laminate- Layers of resin impregnated Kraft paper.

Veneers- Can be bent around a mould and formed into complex shapes.

Laminating using a male and female mould or you can laminate using a vacuum bag or vacuum frame.





Stem Bending

Lignin- Natural plastic, Heats up and lets fibres move.

Cost- Low tooling cost.
Quality- Good quality and high strength.
Typical Applications- Boat, Furniture, Instruments.

Childrens Chair, Mini project

Theory Lesson WOOD

Wood

Soft wood : Coniferous, Larch. Spruce, scots Pine, Douglas Fir

• Evergreens
• Grows faster

Hardwoods: Deciduous, Ash, oak, Beach, Teak, Walknut

• Slower growing,
• Leaves
• Expensive

Structure of wood:

• Wood is fibrous with fiber running along the length.
• Full of moisture.

Harvesting:

• Cutting down the tree.

Conversion:

• cutting the trunk
• Slab sawn, use of the whole tree, more likely to bend and warp
• Quarter sawn, lots of excess wodd not being used. less likely to deform over time.

Seasoning:

• Reducing moisture content, 70% of a tree is made up of water
• Natural
• Kiln seasoning

Board Preparation:

• Sawing to size.
• Planed all round, PAR
• Quarter Sawn.

Properties!

• Physical strength: Timber is a much stronger along the grain than across it.
• Aesthetic properties: Colour, Complex or simple grain structure.
• Moisture content: Shrinkage, Timber movement
• Protection: Dry and wet rot; insect attack.
• Operating conditions: Where will the time be used?
• Cost: Hardwood = expensive softwood = cheaper.
• Sustainability: using timber for sustainable sources.
• Sizes of board: wood can come in a variety of different sizes.

FSC: Forestry Stewardship Council, Tree protection agency.