I.T. Seasoning, Plastics, Metals, Hand tools

• Seasoning


  The process of reducing the moisture content in green timber to make it usable
• Green timber


  Timber that contains a large amount of moisture (around 70% water)
• Problems with green timber

  • - It is heavy due to excess water
  • Its strength is reduced
  • It is attacked by insects and fungi
  • It is difficult to cut by hand or machine
  • Adhesives have little or no effect
• Seasoning


  The process of reducing the moisture content in timber to below 18% for general purposes and below 12% for centrally heated buildings
• Methods of reducing moisture content in timber

  • - Air or Natural Seasoning
  • Kiln or Artificial Seasoning
• Air/Natural Seasoning


  • Timber is stacked with sticks between to allow air circulation
  • Ends are painted or nailed with thin strips to prevent faster drying and splitting
  • Relies on sun and wind to provide drying
• Air/Natural Seasoning


  • - Cheap
  • Needs less attention
  • Does not have to be skilled
  • Easier
• Air/Natural Seasoning


  • - Takes a long period
  • Easily affected by the weather
  • Difficult to attain below 12% moisture
  • Harder to kill insect eggs
• Kiln/Artificial Seasoning


  • Timber is stacked on trolleys and pushed into a sealed kiln
  • 3 stages:

  1. Steam is injected to free moisture from wood cells

  2. Steam is reduced and temperature increased for further drying

  3. Steam is turned off and hot dry air is used
• Kiln/Artificial Seasoning


  • - Temperature of circulating air can be regulated
  • Humidity of circulating air can be controlled
  • Rate of air circulation through the kiln can be controlled
• Kiln seasoning uses steam as the source of heat, and the heated air is directed through a chamber containing the pile of timber
• The air is made artificially humid according to the stage of drying by means of steam or water sprays
• Plastics


  Manmade materials which are produced from the use of fossil fuels such as natural gas, coal and crude oil being the most common type in creating synthetic plastics
• Categories of plastics


  • Natural plastics
  • Semi-synthetic plastics
  • Synthetic plastics
• Natural plastics


  Naturally occurring materials that can be shaped and molded by heat, e.g. amber
• Semi-synthetic plastics


  Made from naturally occurring materials that have been modified or changed by mixing other materials with them
• Synthetic plastics


  Materials that are derived from breaking down, or 'cracking' carbon based materials, usually crude oil, coal or gas, so that their molecular structure changes
• Categories of synthetic and semi-synthetic plastics

  • Thermoplastics
  • Thermosetting plastics
• Thermoplastics


  Plastics that can be heated and molded into different shapes, and will retain that shape when cooled. The process can be repeated many times.
• Thermosetting plastics


  Plastics that can be shaped only once and cannot be reshaped when heat is applied. They do not soften when heated, but stay hard and rigid.
• Metals


  Materials that do not occur naturally but are created from raw materials known as ores
• Process of getting metal from ore

  1. Dig up

  2. Concentrate

  3. Extract

  4. Purify

  5. Manufacture
• Categories of metals


  • Ferrous metals
  • Non-ferrous metals
  • Alloys
• Ferrous metals


  Metals which contain mainly iron and small portions of other metals
• Non-ferrous metals


  Metals which contain little or no iron
• Examples of non-ferrous metals

  • Aluminum
  • Copper
  • Zinc
  • Lead
  • Tin
• Alloys


  Combinations of two or more pure metals, made by mixing molten metals and allowing them to solidify
• Examples of alloys


  • Silver coins (75% copper, 25% nickel)
  • Copper coins (97% copper, 2.5% zinc, 0.5% tin)
  • Stainless steel (70% iron, 20% chromium, 10% nickel)
  • Mild steel (99.7% iron, 0.3% carbon)
• Hand tools


  Devices for performing work on a material or physical system using only hands, either manually or electrically powered
• Categories of hand tools

  • Marking
  • Measuring
  • Holding
  • Cutting
  • Boring
  • Driving
• Examples of measuring tools

  • Measuring tape
  • Carpenter's level
  • Calipers
• Examples of cutting tools

  • Crosscut saw
  • Ripsaw
  • Circular saw
• Examples of holding tools

  • Hand vises
  • Pliers
  • G-clamp
• Examples of driving tools

  • Screwdriver