Materials,tools and wood

Materials,tools and wood

1. materials and raw materials

   • Selecting materials
     • The type of material:they can be natural or man-made
     • Function:one their function is , for example, creating a pleasing appearence
     • Durability:how long should the solution last?
     • Cost of materials:what is our budget?
     • The kinds of additional elements that need to be included:which
     • The techniques tobe used:do we know/can we learn the techniques we need to work with the materials and tools available to us ina a resonable period of time?
   • Raw materials
     • Are products extracted from nature.
   • Natural and processed materials
     • A technological product is an object made using materials,designed by humans to meet a specefic need.

2. Properties of materials

   • Mechanical properties
     • Mechanical resistance:the ability of a body to resist the forces applied to it without breaking or changing in shape
     • Toughness:a body's resistance to being changed,eformed or broken
     • Brittleness:the ability of an object to break easily, without being deformed hardly at all
     • Elasticity:the ability of a material to return to its original shape after being deformed under external forces after they stop
     • Plasticity:the ability of a body to become permanently deformed without breaking, once its elastic limit has been exceeded
     • Hardness:the resistance of a body to being pierced or scratched by another body
   • Thermal properties
     • Thermal conductivity:the ability to transmit heat
     • Expansion:the increase in size observed in a body when its temperature rises
   • Enviromental properties
     • Toxicity:how strong a poison or toxin is
     • Enviromental hazard:the level of toxic effect a contaminant has on an ecosystem
     • Biodegradability:a material's ability to naturally decompose
     • Reciclabity:the possibility of reusing a material for either the same purpose it was made for or a different one

3. Tools

   • What is a tool?
     • Tools may be defined as objects designed to carry out mechanical work and tasks
   • Machine tools
   • The first tools made by humans

4. Wood

   • Parts of the trunk
     • Bark:protects the wood from illnesses and external attacks
     • Pith:this is the central part of the trunk and it is not very sturdy
     • Sapwood:is the young part of the wood.It tends to be lighter in colour and is used for work with few mechanical or asthetic requirements
     • Growth rings:each ring corresponds to one year of the plant's life
     • Cambium:this is the tree's growth layer,made up of living cells
     • Heartwood:this is hard,compact wood.It's made up of physiologically inactive cells and is found in the center of the tree
   • Types of wood
     • Non-resinous:it comes from trees that have little resin and a fibrous texture
     • Resinous:it usually comes from evergreen trees,wich prodece resin
   • Obtaining wood
     • To obtaing wood, trees must be felled
   • Properties
     • Sound conductivity:wood conducts sound very well,owing to its low density and high elasticity
     • Density:is the ratio of mass to volume of the material
     • Thermal and electricalbinsulation:is a good insulator
     • Flexibility:is the ability to be deformed in the direction of the fibres without breaking
     • Hidroscopicity:is the ability to absorb or release moisture. It afect the volume and weight
     • Hardness: is resistance againts being pierced or scratched by another object
     • Toughness:it is very resistant to breaking when hit by something
     • Splitability:refers to how easily it splits in he longitudinal direction of the fibres
   • Different forms
     • Natural wood
       • Boards and planks:are used for building and in tha furniture industry
       • Sheets or veneers:thin pieces used to cover surfaces
       • Beams:are used as structural elements in construction.
       • Mouldings or porfiles:thes pieces are similar to strips but are more complex in shape.They are used for decoration
       • Strips:are pieces of wood with square,rectangular or circular cross-section.They come in diferent thicknesses and are used to make models,trims or drawer rails
       • Panels:are pieces of wood with a large surface,made by joining several boards together