3.2 Performance Characteristics of Woods

Question 1

Name some of the Performance Characteristics of woods

Answer 1

• Grain pattern or direction
• Warpage, shrinkage and splitting
• Machining qualities
• Resistance to decay and moisture
• Toxicity

Question 2

How can the structure of wood grain can affect workability and cost?

Answer 2

• Hardwoods can be prized for their decorative grain pattern
• Beech has a tight and fine grain which makes it easy to turn
• Wood will always split in the direction of the rays in the grain

Question 3

What is an anisotropic material?

Answer 3

Materials whose properties vary when measured in different directions

Question 4

What is wood seasoning?

Answer 4

It’s the process of drying timber to remove moisture in the cells of the wood walls to prevent warpage, shrinking and splitting

Question 5

How can timber be prevented from distorting?

Answer 5

It must be seasoned as it makes wood more stable (making it less likely to change shape or size during/after manufacture)

Question 6

How can distortion happen in wood?

Answer 6

• Wood is hygroscopic (it absorbs moisture and swells up in damp conditions)
• As water evaporates from the timber, it shrinks
• If moisture evaporates too quickly, or unevenly, the wood can distort –it may twist, warp, bow, cup or split

Question 7

What is air-dried (AD) wood?

Answer 7

When the timber stored under cover and left to dry naturally

Question 8

What is kiln-dried (KD) wood?

Answer 8

When the timber is artificially dried using steam to speed up the drying process

Question 9

When does wood shrink?

Answer 9

It shrinks with the seasons or with the level of moisture in any given environment

Question 10

What does forming consist of?

Answer 10

• Additive manufacturing
• Wasting processes
• Manipulation

Question 11

Name a wasting process

Answer 11

Carving, turning, milling and routing

Question 12

Name a manipulation process

Answer 12

Steam bending

Question 13

What is steam bending?

Answer 13

It uses heat and moisture to make wood bendable without breaking until it is cool and dry

Question 14

What is laminating?

Answer 14

The process of bonding materials together, usually wood veneers, this process is commonly used to create beams, panels, or curved components.

Question 15

Why is teak suitable for an outdoor garden bench?

Answer 15

• It contains natural oils resistant to moisture, making it very resistant and unlikely to quickly degrade due to the effects of weathering.
• It contains natural oils which resist acid and alkalis, meaning thebench is unlikely to degrade due to bird droppings or cleaning detergents
• It is aesthetically pleasing due to teh natural dark brown/red colour and straight grain
• It is hard, meaning it will withstand scratches from items such as buttons on people’s jeans when they sit down or move around the bench