industrial techniques

• Trees


  Primary sources of lumber used in various applications such as building and furniture construction
• Trees

  • Roots
  • Trunk
  • Crown
• Purposes of tree parts

  1. Roots: Anchorage, water/mineral absorption, food storage

  2. Trunk: Lumber, structural support, crown support

  3. Crown: Photosynthesis, shelter, beautification
• Tree structure

  • Bark
  • Inner Bark/Bast
  • Cambium Layer
  • Sapwood
  • Heartwood
  • Pith
  • Annual Rings
  • Medullary Rays
• Felling


  Cutting down and cleaning up a mature tree
• Conversion


  Cutting logs into boards
• Types of conversion

  • Plain/Slash/Through & Through Sawing
  • Quarter/Radial Sawing
• Plain Sawing

  • Advantages: Less time, cheaper, requires less skill
  • Disadvantages: Boards with long annual rings, prone to warping, less durable
• Quarter Sawing

  • Advantages: More durable, less liable to warp, showcases wood beauty
  • Disadvantages: Expensive, requires more technical expertise, wastes more wood
• Seasoning


  Reducing moisture content of timber to make it usable
• Types of seasoning

  • Air/Natural Seasoning
  • Kiln/Artificial Seasoning
• Air Seasoning

  • Advantages: Cheap, less attention needed, no skilled labor required
  • Disadvantages: Slow process, weather-dependent, harder to achieve low moisture content
• Kiln Seasoning

  • Advantages: Faster, easier to reduce moisture content, kills insect eggs, more effective
  • Disadvantages: Expensive to build/run, requires skilled labor, needs more attention, equipment maintenance
• THE STRUCTURE/CROSS-SECTION OF A TREE

  
• BARK: the rough outermost layer that protects the tree from insects, bacteria, fungal attack and evaporation from sunlight.
• Inner Bark/Bast: The second layer of which assists in transporting plant food from the leaves to the rest of the tree.

  • FOOD PRODUCED BY THE MANUFACTURING CENTER IS TRANSPORTED VIA THE BAST
• CAMBIUM LAYER: The third layer of the tree consisting of 2 types of cells, namely;

  1. The bast cells on the outer
  2. Sapwood cells on the inner portion
• Sapwood: This layer of the structure is outer, new wood cells which is responsible for the growth (girth) of the tree.

  • It is normally softer, lighter in color than the heartwood.
• Heartwood: The inner part of a tree trunk that is darker in color than the outer bark.

  • Considered the old wood
  • Harder due to dead cells
  • Drier than the sapwood
• PITH

  • Innermost layer
  • Oldest part of the structure that over a period of time rots and leaves the tree hollow.
• Annual Rings: A series of rings that are formed each year by the growth of a tree.

  • Concentric rings which separate each layer metioned.
• Medullary Rays:

  • Tangential lines/cells
  • They travel from the pith through the bast/inner bark transporting plant food from the bast to the various layers within the structure.
• CATEGORIES OF TREES

  • Hardwood
  • Softwood
• Hardwoods are broad-leaved trees that have leaves actually wider than their length. The seeds are enclosed within the fruit and are found in tropical or sub-tropical climates.
• Softwoods: Coniferous (cone bearing) trees that have needle-like leaves and are usually evergreen-(they don't lose their leaves in winter). Their seeds are not enclosed in the fruit, and are found in cool or cold climates.
• Hardwoods can either be Deciduous or Evergreen.

  These trees are commonly found in places like

  • Africa
  • New Zealand
  • Europe
  • East & West Indies
• Softwoods are commonly found in regions such as

  • Canada
  • Northern Russia
  • Sweden
  • Scandinavia
• EXAMPLES OF SOFTWOODS

  • FIR
  • SPRUCE
  • CEDAR
  • LARCH
  • PINE
  • GIANT REDWOOD
• EXAMPLES OF HARDWOODS

  • ASH
  • MAHOGANY
  • SYCAMORE
  • MAHOE
  • OAK
  • BEECH
  • ELM