5B -Timber based materials Flashcards
how is Chipwood made?
small chips of timber glued together to make a dense sheet
how is MDF made?
small timber fibres, mixed with wax and resin
how is plywood made?
gluing three layers of sheet timber (turning them 90° each time)
how is plywood strengthened?
timber is glued at right angles to each other
what kind of force is torsion?
a twisting force
what is kerfing?
Slots cut into a material to aid bending (then put glue into the slots)
what is high cross-sectional stability?
the ability to withstand flexing (ie. thick plywood)
how do you minimise the impact on deforestation?
if more trees are planted than are cut
why cannot MDF be recycled?
as it is made of gluing pieces of timber together (and glue cannot be recycled)
what are the 6 Rs when designing new products/it’s packaging?
- Reduce
- Reuse
- Recycle
- Rethink
- Refuse
- Repair
how long do hardwood trees take to grow?
60- 100 years
List Hardwood trees
ash, balsa, beech, mahogany, oak
how long do softwood trees take to grow?
25 to 30yrs
list softwood trees
larch, pine, spruce
describe the process of conversion
- tree trunks transported to sawmill
- trees cut to usable planks
what is freshly cut timber called?
green timber - high water content
what is dried out timber called?
seasoned
what is an issue with working with MDF?
creates a lot of dust when being worked on
how do you recycle softwood to make a wood filler?
use the sawdust from wood and mix it with wood glue
describe how wood is processed
1) tree is cut down (felled)
2) tree is debarked
3) then converted to planks
why is tessellation important when forms are cut from a log?
so that little waste occurs
What is the process of PAR (planed all round), used to do?
reduce the size and achieve a smooth finish (easier to work with)
what is rough sawn timber?
when timber has not been planed and is rough to the touch
state the features of PAR wood
- internal joinery
- does not absorb much liquid (varnishes well)
is PAR or rough sawn wood cheaper and why?
Rough Sawn is cheaper as it takes less time to produce (no extra processes)
advantages of kiln drying
- faster than air
- kills bacteria and insects
(damage wood)
what is beech used for?
children’s toys, kitchen worktops, tool handles, chopping boards
what would happen if chipboard becomes wet?
the wooden fibres would absorb the water and cause the chipboard to swell
what is chipboard normally covered with?
polymer laminate
why is chipboard used in flat pack-furniture a lot
it has no grain, can be drilled and cut with ease
what is the difference between PSE and PAR?
PSE has one planed edge
PAR both edges and sides are planed
would planed timber be used for framework of roofs?
no, as the interior work would be seen
what do planks and boards refer to?
the proportional dimensions of the timber
what does moulding refer to?
piece of timber that has a decorative pattern along its length (our skirting board)
what machine is used to add a decorative pattern to a length of timber?
spindle moulder
what is veneer?
a thin sheet of timber (made from a hardwood)
what is veneer used for?
covering a cheap material with an expensive hardwood layer
why is hardwood more expensive?
- longer time to mature
- are sometimes denser than softwoods
disadvantages of hardwood?
- tougher to sand + plane
- expensive
disadvantages of softwood
- sometimes have knots
advantages of softwood
have looser grains and take less time to mature
what are the advantages of composite boards?
- stronger
- more eco friendly
- cheaper
- durable
- smoother
what kind of items are made during batch production?
many items of the same product are produced
what is a rip sas used for?
ripping/ rough cutting thicker planks and boards
what is a tenon saw used for?
cutting straight lines with accuracy
what saws are used to cut thinner pieces of timber which can cope with curves?
coping saws/ jig saws/ scroll saws
how do twist drills work?
drill a hole of fixed diameter into timber
how do countersink bits drills work?
used to profile a hole - top bit
so the top of the screw can sit without a bump in the surface
why and when would continuous production be used?
- when products are in high demand or thousands of people use them
- processing of timber/logs
features of continuous production
- high tooling/machine costs (perform specific tasks quickly)
- unit cost per product is cheap
features of mass production machinery
- tooling/machine costs relatively high
- flexibility to change dimensions
when would mass production be used?
- products in thousands
- softwood products (easier to source)
when would batch production be used?
- products in smaller quantities
- product with smaller shelf life (be adapted and changed)
what kind of workers are required for batch production?
moderately skilled worker
what are sliding bevels used for?
marking the same chosen angle every time (maintains position)
why are hand saws useful?
you can cut them at many angles
what does a router do?
- cuts into a piece of wood in many directions
- uses a rotary cutter (guided in directions)
advantages of a circular saw?
- quick and efficient
- use different blades
- guide machines with straight lines
adv/dis of machine tools?
+ offer speed and precision
- loud, expensive, bulky
what is a band saw?
big one mr harper used to cut large wood into smaller ones for my box
use of planer thicknesser?
- reduce material thickness
- smooth new sheet material for an even finish
use of lathe?
make cylindric objects (bannister)
what drill can drill holes of varying depths and thicknesses?
pillar drill
what is an acceptable dimension a piece can be? (word for it)
tolerance
what is the accepted dimension a piece can be?(measurement)
+- 1mm
what is a CNC router?
a machine that follows a cutting path that has has been designed in a computer
adv/dis CNC?
ADV - need less people working on the job
- increase products made
- speed up production/accuracy
DIS - initial cost of tooling is high
what is a wood stain used for?
to enhance the appearance of wood
why are kitchen worktops anc chopping boards often iol/ wax soaked?
so the surface repels water
what is the purpose of a varnish?
give a shiny appearance
what is involved within the process of pressure treated timber?
a protective chemical is forced into the fibres of timber
how does pressure treated timber affect the lifespan?
increases it, protecting against rot
difference between dip treated timber and pressure treated timber?
dip = only surface pressure = deep inside wood
