Wood
1. Name 5 objects that are made out of wood. Is the same
TYPE of wood used in all of these objects? If not, how
does the wood differ?
2. What types of trees are used to make wood? What part of
a tree is used to manufacture wood?
3. What mechanical properties does wood possess? What
factors can effect the mechanical properties of wood?
4. Why is wood a commonly used material in the
manufacture of technical objects?
5. What is modified wood made of and what is the advantage
of using this material over natural wood?
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Wood Terminology
Hard wood—Soft woods
• All native species of trees are
divided into two classes.
– Hard wood have broad leaves and are deciduous
– ex: Maple, yellow birch, oak
– Soft woods are conifers
– ex: spruce, pine, cedar
2
Materials obtained from trees come from…
Sap wood
• Sapwood: the outer portion that
conducts sap and has the living
cells.
Bark
• Heartwood : the inactive cells in the
inner portion.
– Mineral deposits may cause
darker color.
– Deposits make wood more
durable.
Heart wood
Tree roots, branches and bark have little to no commercial value
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Wood Terminology--cont.
Growth rings
• Because the rate a tree grows
change with the seasons, a cross
section will show distinctive rings.
• Springwood
Summerwood
– Inner part of the growth ring
– Usually larger cavities and thin
walls
• Summerwood
– Outer part of growth ring
– Smaller cells and thicker walls.
• A tree grows one springwood and
one summerwood ring each year.
– Used to age trees
Springwood
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Wood Terminology--cont.
Sawing Direction
• Plain sawn (Flat sawn)
– Board is sawed “parallel” to growth rings
– Most common boards.
• Quarter sawn
– Log is first quartered
Were have you seen
quarter sawn boards
used?
– Boards are cut “perpendicular”
to the grain.
– Usually must be special ordered.
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What factors can effect the mechanical properties of wood?
Why is wood a commonly used material in the manufacture of
technical objects?
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5) What is modified wood made out of?
Modified wood is treated wood or material made
with wood mixed with other substances such as
glue, plastics or preservatives.
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Treated Wood
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Laminated Wood
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Plywood
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Particle Board
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Fiberboard
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5) What is the advantage of using this modified wood
over natural wood?
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