Processing of Timber

Question 1

What are the two processes of processing timber

Answer 1

• cutting into visible sizes

- maximise yeild

Question 2

what is the definition of conversion

Answer 2

cutting of freshly felled timber into usable sizes

Question 3

cutting of freshly felled timber into usable sizes refers to

Answer 3

Conversion

Question 4

what will determine the orientation and distribution of cells in sawn timber

Answer 4

cutting process

Question 5

plain sawing produces a high

Answer 5

yield… but it’s properties differ from those of it’s neighbours

Question 6

True radial sawing produces planks with…

Answer 6

identical properties…. but involves a high waste rate

Question 7

what are the two types of growth defect

Answer 7

shakes and knots

Question 8

shakes and knots are types of

Answer 8

growth defect

Question 9

shakes are…

Answer 9

splits in the timber

Question 10

knots are formed when…

Answer 10

branches grew out of the trunk

Question 11

wane is a defect from the ….. process

Answer 11

conversion

Question 12

wane is….

Answer 12

the presence of bark on the outer edge of the plank and has aggressive grain slope.

Question 13

what is seasoning

Answer 13

this is the controlled reduction in moisture content

Question 14

the controlled reduction in moisture content is also known as

Answer 14

seasoning

Question 15

what is the equation for moisture content in timber

Answer 15

wet - dry / dry x 100

Question 16

freshly felled or green timber can have a moisture content of

Answer 16

150%

Question 17

timber must be dried to have a moisture content below 20% to eliminate

Answer 17

fungal attack

Question 18

timber that is stacked in open sided sheds and allowed to dry naturally is know as

Answer 18

air seasoning

Question 19

timber that is heated to expel moisture is known as

Answer 19

kiln seasoning

Question 20

what is the fibre saturation point

Answer 20

this is when water is removed from the cell cavities, and the only remaining water is that contained within the cell walls.

Question 21

drying beyond the fibre saturation point will result in

Answer 21

shrinkage and changes in mechanical properties

Question 22

too rapid drying of the surface layers can lead to the surface experiencing tensile forces which will result in

Answer 22

splits and checks

Question 23

timber is a …. material

Answer 23

anisotropic

Question 24

how does shrinkage occur in timber

Answer 24

tangential - radial - longitudinal

Question 25

timber below the fibre saturation point is a ….. material

Answer 25

hygroscopic

Question 26

a hygroscopic material can

Answer 26

absorb water from moist air and lose moisture to dry air

Question 27

timber is not truly elastic in its response to stress, it is…

Answer 27

viscoelastic

Question 28

what is viscoelastic

Answer 28

it simultaneously manifests the properties of an elastic solid and a viscous liquid.

Question 29

viscoelasticity is property associated with creep, under static loading timber undergoes…

Answer 29

instantaneous elastic strain followed by time dependent strain.

Question 30

what are the major limitations to timber

Answer 30

variability in properties
anistropy
limited size availability at reasonable cost