design technology

design technology

1. materials

   • wood
     • softwood comes from coniferous trees which are evergreen,needleleaves,cone bearing treessuch as pine,cedar,fir.
     • hardwood comes from broad leaves decious trees the main hardwood timbers are ash,beech,birch,cherry,elm,mahoganyetc
   • metal
     • ferrous metals contain iron examples are cast iron,mild steel,medium carbon steel,high carbon steel,stainless steel and high speed steel.
     • non ferrous metals do not contain iron some common metal are alluminum,cooper,zinc,brass,tin
   • plastics
     • natural plants - from which cellulose can be extracted,trees from which latex,amber and resin can be extracted,animals from which horns and milk used for glues obtained,insects from which sheelac used to make polishes obtained.
     • synthetics are plastics which are chemical manufactured eg crude oil,coal,natural gas
   • composite materials
     • composite materials are formed by combinding a reinforing materials such as wood pulp and bonding agent such as waste cutting of solid wood which makes mdf,gfp.
   • smart material
     • thermochramic piaments react to change of temp.
       • photochromic piaments react to changes of light levels.

2. health and safety

   • tools and equipment should be stored so that sharp edges and blades are protected power tools should be isolated from electrical supply operators should be fully trained in the use of tools and equipment personal protective equipment should be used all guards and other protective devices should be in place at all times when the equipment is in use
   • materials must be stored so that sharp edges and ends cannot cause harm gloves should be used when handling materials with sharp edges all chemicals, finishes and solvents should be stored correctly in accordance with the manufacturer's instructions some materials may need special storage away from other substances.
   • when using toxic or flammable substances, personal protective equipment should be used care should be taken to avoid excess contact with toxic substances turn off naked flames when flammable substances are used.

3. compounds joints and adesive

   • Permanent and temporary joints Permanent joints are intended to stay put. They may be assembled using adhesives, nails, rivets, or one of the heat processes of brazing, soldering or welding. Assembly jigs are often used to hold components in place while they are being joined. For example, the parts of a steel roof frame can be put into the jig and then welded together.