Exam Style Questions: Performance Characteristics of Woods Flashcards
Give one reason why selling materials in stock forms is beneficial for the manufacturer (1 mark)
- Allows materials to be shipped and transported more conveniently to the point of sale.
- Allows the manufactures to accurately meet the needs and requirements of the consumer.
- Makes re/ordering easier.
- Fewer stock sizes needed to be stocked.
Give one reason why buying materials in stock forms is beneficial for the customer (1 mark)
- Makes planning and designing easier by working to specific dimensions.
- It is easier to calculate and work out the correct materials needed for a particular job.
- They are easier to transport home.
- Easier to store before use.
- You can buy only what you need.
- Easier to compare prices of similar materials from different manufacturers.
- Makes re/ordering easier.
Oak is highly prized for its aesthetically pleasing grain and durability.
Explain some limitations of using this material (4 marks)
Cost – oak is an expensive hardwood
Components – Tannic acid in oak corrodes steel so non-ferrous fixtures and fittings must be used
Size – Size is limited by the shape and form of the tree
Time – Oak takes a long time/ fifty to hundred or more years to grow
Can manufactured boards be considered eco-friendly?
They can be considered environmentally friendly as waste wood or parts of a tree that would otherwise be useless are used in the manufacture of many manufactured boards. The large format sheets and uniform strength mean that parts can be nested/tessellated to avoid wasteful offcuts. However, the adhesives/resins which hold them together are not usually environmentally friendly. Composite materials such as MDF are not recyclable.
Select one of the following materials that originates from a deciduous tree (1 mark) • Cedar • Douglas fir • Mahogany • Spruce
- Mahogany
a) State what PAR stands for (1 mark)
b) Define what PAR means (2 marks
a) Planed All Round
b) 1 mark for reference to planning/machining
1 mark for reference to square / 90°
PAR timber has been machined/planed on all sides to ensure that the material
is square
A PAR piece of hardwood is sold at a nominal size of 25 x 150 x 2000mm.
(a) Calculate what the actual size of the piece would be (2 marks)
(b) Explain your answer (3 marks)
a) 25-6 = 19; 150-6 = 144 (1) accept a reduction of 2mm per face
19 x 144 x 2000mm (1). No reduction of length.
b) The planning process removes approx. 3mm (1) of material from all planed
sides (1) The length of the timber is not affected during the planning process (1)
Name two types of particle board that could be used in the manufacture of computer desks (2 marks)
- Medium density fibreboard / MDF
- Chipboard
- HDF
Evaluate the advantages of using the manufactured board to make a computer desk (6 marks)
- Material is available in large format boards which allow parts to be tessellated / can reduce waste
- Large boards are suitable for machining using CNC which speeds up manufacture / reduces labour costs
- CNC can be used to cut complex shapes to create interesting desk shapes and cut out holes in the desk for wires and cables
- Manufactured materials are defect free which reduces waste/means the quality of the material is consistent
- Boards accept a paint finish or veneer/laminate finish readily, so their aesthetics can be improved
- Boards can be made water-resistant/wipe-clean/more durable
- Boards are a consistent thickness which makes them ideal for flat pack constructions and the use of KD fittings
Give one suitable application and three characteristics of the following woods:
(a) Larch
Application: (1 mark)
Characteristics: ( 3 marks)
(b) Beech
Application: (1 mark)
Characteristics: ( 3 marks)
a) Application: Veneers, outdoor furniture, fencing, cladding, decking, boat making.
Characteristics: 1 mark per relevant point
Hard, reddish-brown in colour, colour fades in sun/UV, high resin content
which can clog up cutting blades, and does not require treatment for outdoor
use.
b) Application: Toys, kitchen equipment, furniture, tool handles. Accept any suitable
application.
Characteristics:1 mark per relevant point
Hard, tough, odourless, close and straight grain,
open pore structure ideal for steam bending, non-toxic, warps easily.
Define the term ‘seasoning’ when working with woods (2 marks)
Seasoning is a process of removing moisture (1) from wood to prepare it
for general use (1).
Give two properties that you would expect to be improved through the process of seasoning (2 marks)
1 mark per relevant point up to a maximum of 2 marks.
The wood is: stronger, more stable; less likely to decay / rot; less prone to insect attack; less likely to corrode metals; easier to preserve as it absorbs preservatives more readily.
a) Materials corrode, decay or decompose over time. Rot causes decay in woods. Name two other ways in which wood can decay (2 marks)
b) Select one of the ways wood can decay from question (a) and explain the process of decay in more detail (2 marks)
a) - Fungal attack, insect attack
b) Award 1 mark per relevant point up to a maximum of 2 marks.
Fungal attack: Fungal spores attack wood (1) by attaching themselves to wood and then feeding off (1) the nutrients stored in wood cells (1). Fungi need oxygen and moisture to grow (1).
Insect attack: Insects attack wood as a food source (wood cellulose) (1). Insects lay eggs in the wood (1) so the larvae have a food supply when they hatch (1). The wood also offers protection to the larvae (1) until they mature.
Give two ways in which can you prevent decay (2 marks)
Keep wood dry (1), keep environment ventilated (1), add a preservative/protective finish (1), use a timber with a naturally high oil content (1).
Evaluate the use of woods with a high oil/resin content (6 marks)
Advantages:
- Wood is less likely to decay as oil keeps moisture out of the material
- Less prone to insect attack as the moisture of the wood is reduced
- Less prone to fungal attack as the moisture of the wood is reduced
- More resistant to wet/moist environments as oil repels water
- Many do not require treatment for outdoor use
Disadvantages:
- Woods with high oil content often comes from hardwood species that are
more expensive and take a long time to mature
- Wood can be difficult to treat with a finish as the wood is saturated with
natural oils; wood with a lower natural oil content accepts finishes more
readily
- Wood can be difficult to glue because the oil affects the ability of the
adhesive to bond surfaces together
